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Fastest Way to Compare Strings in C# .Net

What is the fastest way to compare strings in C# .Net? Everyone’s had to do it. A lot of people instinctively use the C# “==” operator. In several programming forums I’ve posted to, quite a few haven’t been aware of other built in methods or techniques that can be used, such as SequenceEqual, comparing ByteArrays, or simply using the favorite Dictionary/Hashset objects to check against the keys.

The Background:

Comparing strings is one of the basic fundamentals in any programming language. The most common syntax across multiple languages is simply the “==” operator. In C# .Net, the “==” operator isn’t always appropriate to use. Thus, Microsoft has included additional methods to compare string values. Then there are ways of comparing strings, which a lot of C# programmers have done, but may not realized. For example, checking a Dictionary object to determine if it contains a particular string as a key. That in itself is doing a string comparison.

With that said, what is the fastest way to compare strings in C# .Net? Is anyone else as curious as this Curious Consultant?

So let’s get started.

The Gist of it All:

I implemented what I think would be the most common ways of doing string comparisons. I chose the Dictionary and Hashset objects as the choice when comparing against keys because they proved to be the fastest in my test on collections for fastest string look ups (http://cc.davelozinski.com/c-sharp/fastest-collection-for-string-lookups) test.

If there’s another method people have, let me know so I can include it in the code!

Here’s the gist of the tests I included:

Code Snippet:

Case Sensitive:

if (stringsWeWantToSeeIfMatches[x] == stringsWeAreComparingAgainst[x])

1	if (stringsWeWantToSeeIfMatches[x] == stringsWeAreComparingAgainst[x])

String.Compare

if (string.Compare(stringsWeWantToSeeIfMatches[x], stringsWeAreComparingAgainst[x], caseSensitive) == 0)

1	if (string.Compare(stringsWeWantToSeeIfMatches[x], stringsWeAreComparingAgainst[x], caseSensitive) == 0)

String.CompareOrdinal

if (string.CompareOrdinal(stringsWeWantToSeeIfMatches[x], stringsWeAreComparingAgainst[x]) == 0)

1	if (string.CompareOrdinal(stringsWeWantToSeeIfMatches[x], stringsWeAreComparingAgainst[x]) == 0)

String.Equals

if (String.Equals(stringsWeWantToSeeIfMatches[x], stringsWeAreComparingAgainst[x]))

1	if (String.Equals(stringsWeWantToSeeIfMatches[x], stringsWeAreComparingAgainst[x]))

char by char

isDifferent = false;
if (stringsWeAreComparingAgainst[x].Length != stringsWeWantToSeeIfMatches[x].Length)
{
    isDifferent = true;
    continue;
}
else
{
    for (int y = 0; y < stringsWeWantToSeeIfMatches[x].Length; y++)
    {
        if (stringsWeWantToSeeIfMatches[x][y] != stringsWeAreComparingAgainst[x][y])
        {
            isDifferent = true;
            break;
        }
    }
    if (!isDifferent)
        numberOfMatches += 1;
}

isDifferent = false;

if (stringsWeAreComparingAgainst[x].Length != stringsWeWantToSeeIfMatches[x].Length)

{

isDifferent = true;

continue;

}

else

{

for (int y = 0; y < stringsWeWantToSeeIfMatches[x].Length; y++)

{

if (stringsWeWantToSeeIfMatches[x][y] != stringsWeAreComparingAgainst[x][y])

{

isDifferent = true;

break;

}

if (!isDifferent)

numberOfMatches += 1;

}

Byte Arrays

b1 = Encoding.Unicode.GetBytes(stringsWeWantToSeeIfMatches[x]);
b2 = Encoding.Unicode.GetBytes(stringsWeAreComparingAgainst[x]);
if (b1.SequenceEqual(b2))

b1 = Encoding.Unicode.GetBytes(stringsWeWantToSeeIfMatches[x]);

b2 = Encoding.Unicode.GetBytes(stringsWeAreComparingAgainst[x]);

if (b1.SequenceEqual(b2))

Dictionary Key

if (d.ContainsKey(stringsWeWantToSeeIfMatches[x]))

1	if (d.ContainsKey(stringsWeWantToSeeIfMatches[x]))

Hashset Key

if (hs.Contains(stringsWeWantToSeeIfMatches[x]))

1	if (hs.Contains(stringsWeWantToSeeIfMatches[x]))

IndexOf

if (stringsWeAreComparingAgainst[x].IndexOf(stringsWeWantToSeeIfMatches[x]
, 0
, stringsWeWantToSeeIfMatches[x].Length) == 0)

if (stringsWeAreComparingAgainst[x].IndexOf(stringsWeWantToSeeIfMatches[x]

, 0

, stringsWeWantToSeeIfMatches[x].Length) == 0)

CommonMethod

numberOfMatches += 
	(
		(stringsWeAreComparingAgainst[x].Length - stringsWeAreComparingAgainst[x]
			.Replace(stringsWeWantToSeeIfMatches[x], String.Empty).Length
		) / stringsWeWantToSeeIfMatches[x].Length > 0 
	? 1 
	: 0
	);

numberOfMatches +=

(

(stringsWeAreComparingAgainst[x].Length - stringsWeAreComparingAgainst[x]

.Replace(stringsWeWantToSeeIfMatches[x], String.Empty).Length

) / stringsWeWantToSeeIfMatches[x].Length > 0

? 1

: 0

);

SequenceEqual

c1 = stringsWeWantToSeeIfMatches[x].ToCharArray();
c2 = stringsWeAreComparingAgainst[x].ToCharArray();
if (c1.SequenceEqual(c2))

c1 = stringsWeWantToSeeIfMatches[x].ToCharArray();

c2 = stringsWeAreComparingAgainst[x].ToCharArray();

if (c1.SequenceEqual(c2))

Case Insensitive:

if (stringsWeWantToSeeIfMatches[x].ToLower() == stringsWeAreComparingAgainst[x].ToLower())

1	if (stringsWeWantToSeeIfMatches[x].ToLower() == stringsWeAreComparingAgainst[x].ToLower())

String.Compare

if (string.Compare(stringsWeWantToSeeIfMatches[x], stringsWeAreComparingAgainst[x], caseSensitive) == 0)

1	if (string.Compare(stringsWeWantToSeeIfMatches[x], stringsWeAreComparingAgainst[x], caseSensitive) == 0)

String.Equals

if (String.Equals(stringsWeWantToSeeIfMatches[x], stringsWeAreComparingAgainst[x],StringComparison.OrdinalIgnoreCase))

1	if (String.Equals(stringsWeWantToSeeIfMatches[x], stringsWeAreComparingAgainst[x],StringComparison.OrdinalIgnoreCase))

ToLower()

if (stringsWeWantToSeeIfMatches[x].ToLower() == stringsWeAreComparingAgainst[x].ToLower())

1	if (stringsWeWantToSeeIfMatches[x].ToLower() == stringsWeAreComparingAgainst[x].ToLower())

ToUpper()

if (stringsWeWantToSeeIfMatches[x].ToUpper() == stringsWeAreComparingAgainst[x].ToUpper())

1	if (stringsWeWantToSeeIfMatches[x].ToUpper() == stringsWeAreComparingAgainst[x].ToUpper())

char by char

isDifferent = false;
if (stringsWeAreComparingAgainst[x].Length != stringsWeWantToSeeIfMatches[x].Length)
{
    isDifferent = true;
    continue;
}
else
{
    for (int y = 0; y < stringsWeWantToSeeIfMatches[x].Length; y++)
    {
        if (char.ToUpperInvariant(stringsWeWantToSeeIfMatches[x][y]) != char.ToUpperInvariant(stringsWeAreComparingAgainst[x][y]))
        {
            isDifferent = true;
            break;
        }
    }
    if (!isDifferent)
        numberOfMatches += 1;
}

isDifferent = false;

if (stringsWeAreComparingAgainst[x].Length != stringsWeWantToSeeIfMatches[x].Length)

{

isDifferent = true;

continue;

}

else

{

for (int y = 0; y < stringsWeWantToSeeIfMatches[x].Length; y++)

{

if (char.ToUpperInvariant(stringsWeWantToSeeIfMatches[x][y]) != char.ToUpperInvariant(stringsWeAreComparingAgainst[x][y]))

{

isDifferent = true;

break;

}

if (!isDifferent)

numberOfMatches += 1;

}

Byte Arrays

b1 = Encoding.Unicode.GetBytes(stringsWeWantToSeeIfMatches[x]); 
b2 = Encoding.Unicode.GetBytes(stringsWeAreComparingAgainst[x]);
if (b1.SequenceEqual(b2))

b1 = Encoding.Unicode.GetBytes(stringsWeWantToSeeIfMatches[x]);

b2 = Encoding.Unicode.GetBytes(stringsWeAreComparingAgainst[x]);

if (b1.SequenceEqual(b2))

Dictionary Key

if (d.ContainsKey(stringsWeWantToSeeIfMatches[x]))

1	if (d.ContainsKey(stringsWeWantToSeeIfMatches[x]))

Hashset Key

if (hs.Contains(stringsWeWantToSeeIfMatches[x]))

1	if (hs.Contains(stringsWeWantToSeeIfMatches[x]))

IndexOf

if (stringsWeAreComparingAgainst[x].IndexOf(stringsWeWantToSeeIfMatches[x]
,0
,stringsWeWantToSeeIfMatches[x].Length, StringComparison.OrdinalIgnoreCase) == 0)

if (stringsWeAreComparingAgainst[x].IndexOf(stringsWeWantToSeeIfMatches[x]

,stringsWeWantToSeeIfMatches[x].Length, StringComparison.OrdinalIgnoreCase) == 0)

CommonMethod

numberOfMatches += 
	(
		(stringsWeAreComparingAgainst[x].Length - stringsWeAreComparingAgainst[x]
		.ToLower()
		.Replace(stringsWeWantToSeeIfMatches[x].ToLower(), String.Empty).Length
		) / stringsWeWantToSeeIfMatches[x].Length > 0 
	? 1 
	: 0
	);

numberOfMatches +=

(

(stringsWeAreComparingAgainst[x].Length - stringsWeAreComparingAgainst[x]

.ToLower()

.Replace(stringsWeWantToSeeIfMatches[x].ToLower(), String.Empty).Length

) / stringsWeWantToSeeIfMatches[x].Length > 0

? 1

: 0

);

SequenceEqual

s1 = new [] { stringsWeWantToSeeIfMatches[x] }; 
s2 = new [] { stringsWeAreComparingAgainst[x] }; 
if (s1.SequenceEqual(s2, StringComparer.OrdinalIgnoreCase))

s1 = new [] { stringsWeWantToSeeIfMatches[x] };

s2 = new [] { stringsWeAreComparingAgainst[x] };

if (s1.SequenceEqual(s2, StringComparer.OrdinalIgnoreCase))

The code is written in Visual Studio 2013 targeting .Net Framework version 4.5 x64. The source code is available at the end of this blog so you can benchmark it on your own system if you wish.

In a nutshell, the code does the following:

Creates the storage objects, pre-sizing them where possible.
Generates the random strings to compare of varying lengths.
Also generates the strings to search for, purposely copying 1 of every 3 random strings to search to make sure we have at least a few matches.
Performs the comparisons, implementing any of the various techniques in both a case and case-insensitive manner.
Whenever a match is found, a counter is incremented. This is to ensure every technique matches the exact same amount.

The exe file was run on a Windows 7 64-bit with 16 GB memory.

The test was run for the following comparisons:

100 strings
1,000 strings
10,000 strings
100,000 strings
1,000,000 strings

Off To The Races!

My prediction is the Dictionary or Common Custom method will be the fastest. I’ve also heard good things about the String.Compare functions, but haven’t used them enough to form an opinion.

Let’s see what happened on my machine. I ran this test 3 times, only taking the times from the 3rd run.

All times are indicated in seconds.milliseconds format. Lower numbers indicate faster runtime performance.

Winners are highlighted in green; there are no points for second place.

Comparison Performance:
# Strings Being Compared:	100	1,000	10,000	100,000	1,000,000
——– Case Sensitive Comparisons: ——–
==	0	0	0	0.0030001	0.0156000
String.Compare	0	0	0	0.0160009	0.0936001
String.CompareOrdinal	0	0	0	0	0.0156000
String.Equals	0	0	0	0	0.0156001
char by char	0	0	0	0	0.0312001
Using Byte array	0	0	0.0156001	0.0624001	0.4130236
Dictionary Keycheck	0	0	0	0	0.1800103
Hashset Keycheck	0.0030002	0	0	0	0.1860107
IndexOf	0	0	0.0060004	0.0156000	0.1570090
Common Custom Method	0	0	0.0020001	0.0070004	0.0624001
SequenceEqual Method	0.0070004	0.0010001	0.0120007	0.0250015	0.1716003
——– Case Insensitive Comparisons: ——–
==	0	0	0	0.0550032	0.2652005
String.Compare	0	0	0	0.0200012	0.0936002
String.Equals	0	0	0.0010000	0.0150009	0.0468001
ToLower()	0	0.0010000	0.0060004	0.0500028	0.2652005
ToUpper()	0	0.0010001	0.0180010	0.0300017	0.2496004
char by char	0	0	0.0060003	0.0156000	0.2028004
Using Byte array	0	0.0010001	0.0070004	0.0312001	0.3890223
Dictionary Keycheck	0	0	0	0.0156000	0.1810103
Hashset Keycheck	0	0	0	0.0156000	0.1820104
IndexOf	0	0	0	0.0156000	0.1290074
Common Custom Method	0	0	0	0.0312000	0.2808005
SequenceEqual Method	0	0	0	0.0156001	0.1092001

The Results:

Most of the board remained green up through 10,000 comparisons and didn’t register any time.

At the 100,000 and 1,000,000 marks, things started to get a bit more interesting in terms of time differences.

String.CompareOrdinal was the constant superstar. What surprised me is for the case-insensitive comparisons, String.CompareOrdinal outperformed most other methods by a whole decimal place.

For case sensitive comparisons, most programmers can probably stick with the “==” operator.

In Summary:

On my system, unless someone spots a flaw in my test code, if you are doing just a few calls or searches here and there, almost anything should suit your needs and perform fine, especially if you only have a few comparisons to do. Even though there are a few technicalities and times when it shouldn’t be used, I personally like using the “==” operator because it’s simple, straight forward, and incredibly easy to read at just a glance.

The Code:

Note: this code has been updated since the results posted above to utilize the StopWatch for time keeping. The resulting wins/losses are similar, so didn’t feel a need to update the results table.

using System;
using System.Collections.Generic;
using System.Collections;
using System.Collections.Concurrent;
using System.IO;
using System.Linq;
using System.Text;
using System.Text.RegularExpressions;
using System.Threading.Tasks;
using System.Threading;

namespace TestApplication
{
    class Program
    {
        static void Main(string[] args)
        {
            DateTime end;
            DateTime start = DateTime.Now;

            Console.WriteLine("### Overall Start Time: " + start.ToLongTimeString());
            Console.WriteLine();

            #region CompareTwoStrings
            FastestWayToCompareTwoStrings(100, true);
            FastestWayToCompareTwoStrings(1000, true);
            FastestWayToCompareTwoStrings(10000, true);
            FastestWayToCompareTwoStrings(100000, true);
            FastestWayToCompareTwoStrings(1000000, true);
            FastestWayToCompareTwoStrings(100, false);
            FastestWayToCompareTwoStrings(1000, false);
            FastestWayToCompareTwoStrings(10000, false);
            FastestWayToCompareTwoStrings(100000, false);
            FastestWayToCompareTwoStrings(1000000, false);
            #endregion

            end = DateTime.Now;
            Console.WriteLine();
            Console.WriteLine("### Overall End Time: " + end.ToLongTimeString());
            Console.WriteLine("### Overall Run Time: " + (end - start));

            Console.WriteLine();
            Console.WriteLine("Hit Enter to Exit");
            Console.ReadLine();

        }

//####################################################

        //Which way is faster to compare to string?
        static void FastestWayToCompareTwoStrings(int numberOfStringsToCompare, bool caseSensitive)
        {
            Stopwatch sw = new Stopwatch();
            DateTime end = DateTime.Now;
            string[] stringsWeAreComparingAgainst = new String[numberOfStringsToCompare];
            string[] stringsWeWantToSeeIfMatches = new String[numberOfStringsToCompare];
            int numberOfMatches = 0;
            int z = 4;
            bool isDifferent = false;
            byte[] b1 = null;
            byte[] b2 = null;
            char[] c1 = null;
            char[] c2 = null;
            string[] s1 = null;
            string[] s2 = null;
            HashSet<string> hs = new HashSet<string>();
            Dictionary<string, string> d = new Dictionary<string, string>(numberOfStringsToCompare);

            Console.WriteLine("######## " + System.Reflection.MethodBase.GetCurrentMethod().Name);
            Console.WriteLine("######## Number of strings to compare: " + numberOfStringsToCompare.ToString("#,##0"));
            Console.WriteLine("######## Case Sensitive: " + caseSensitive.ToString());
            Console.WriteLine("###########################################################");
            Console.WriteLine();

            try
            {
                //set up the array of strings to use
                Console.WriteLine("###########################################################");
                Console.WriteLine("Starting creating string arrays with " + numberOfStringsToCompare.ToString("#,##0") + " strings");
                Console.WriteLine("###########################################################");

                for (int x = 0; x < numberOfStringsToCompare; x++)
                {
                    //Use the generate password function so we can easily vary the length of the strings and the chars within
                    stringsWeAreComparingAgainst[x] = System.Web.Security.Membership.GeneratePassword(z, z % 4);
                    if (x % 3 == 0)
                    {
                        //to ensure we have some matches
                        stringsWeWantToSeeIfMatches[x] = stringsWeAreComparingAgainst[x];
                    }
                    else
                    {
                        stringsWeWantToSeeIfMatches[x] = System.Web.Security.Membership.GeneratePassword(z, z % 4);
                    }
                    if (!d.ContainsKey(stringsWeAreComparingAgainst[x]))
                    {
                        d.Add(stringsWeAreComparingAgainst[x], string.Empty);
                        hs.Add(stringsWeAreComparingAgainst[x]);
                    }
                    if (z > 25) { z = 4; } else { z += 1; }
                }
                Console.WriteLine("Completed creating string arrays with " + numberOfStringsToCompare.ToString("#,##0") + " strings");
                Console.WriteLine("###########################################################");

                // using the ==
                //it's case sensitive so there will be less matches
                Thread.Sleep(1000);
                numberOfMatches = 0;

                if (caseSensitive)
                {
                    Console.WriteLine("Starting == Case Sensitive: " + DateTime.Now.ToLongTimeString());
                    sw.Restart();
                    for (int x = 0; x < numberOfStringsToCompare; x++)
                    {
                        if (stringsWeWantToSeeIfMatches[x] == stringsWeAreComparingAgainst[x])
                            numberOfMatches += 1;
                    }
                    sw.Stop();
                }
                else
                {
                    Console.WriteLine("Starting == Case Insensitive: " + DateTime.Now.ToLongTimeString());
                    sw.Restart();
                    for (int x = 0; x < numberOfStringsToCompare; x++)
                    {
                        if (stringsWeWantToSeeIfMatches[x].ToLower() == stringsWeAreComparingAgainst[x].ToLower())
                            numberOfMatches += 1;
                    }
                    sw.Stop();
                }
                end = DateTime.Now;
                Console.WriteLine("Finished at: " + end.ToLongTimeString());
                Console.WriteLine("Time to run: " + sw.Elapsed.ToString("mm\\:ss\\.fffffff"));
                Console.WriteLine("Number of Matches: " + numberOfMatches);
                Console.WriteLine();

                Thread.Sleep(1000);
                numberOfMatches = 0;

                //String.Compare
                Console.WriteLine("Starting String.Compare: " + DateTime.Now.ToLongTimeString());
                sw.Restart();
                for (int x = 0; x < numberOfStringsToCompare; x++)
                {
                    if (string.Compare(stringsWeWantToSeeIfMatches[x], stringsWeAreComparingAgainst[x], caseSensitive) == 0)
                        numberOfMatches += 1;
                }
                sw.Stop();
                end = DateTime.Now;
                Console.WriteLine("Finished at: " + end.ToLongTimeString());
                Console.WriteLine("Time to run: " + sw.Elapsed.ToString("mm\\:ss\\.fffffff"));
                Console.WriteLine("Number of Matches: " + numberOfMatches);
                Console.WriteLine();

                Thread.Sleep(1000);
                numberOfMatches = 0;

                //String.CompareOrdinal
                Console.WriteLine("Starting String.CompareOrdinal: " + DateTime.Now.ToLongTimeString());
                sw.Restart();
                for (int x = 0; x < numberOfStringsToCompare; x++)
                {
                    if (string.CompareOrdinal(stringsWeWantToSeeIfMatches[x], stringsWeAreComparingAgainst[x]) == 0)
                        numberOfMatches += 1;
                }
                sw.Stop();
                end = DateTime.Now;
                Console.WriteLine("Finished at: " + end.ToLongTimeString());
                Console.WriteLine("Time to run: " + sw.Elapsed.ToString("mm\\:ss\\.fffffff"));
                Console.WriteLine("Number of Matches: " + numberOfMatches);
                Console.WriteLine();

                Thread.Sleep(1000);
                numberOfMatches = 0;

                //String.Equals
                //put the if statement outside the for-loops so it doesn't impact on run time
                if (caseSensitive)
                {
                    Console.WriteLine("Starting String.Equals Case Sensitive: " + DateTime.Now.ToLongTimeString());
                    sw.Restart();
                    for (int x = 0; x < numberOfStringsToCompare; x++)
                    {
                        if (String.Equals(stringsWeWantToSeeIfMatches[x], stringsWeAreComparingAgainst[x]))
                            numberOfMatches += 1;
                    }
                }
                else
                {
                    Console.WriteLine("Starting String.Equals Case Insensitive: " + DateTime.Now.ToLongTimeString());
                    sw.Restart();
                    for (int x = 0; x < numberOfStringsToCompare; x++)
                    {
                        if (String.Equals(stringsWeWantToSeeIfMatches[x], stringsWeAreComparingAgainst[x], StringComparison.OrdinalIgnoreCase))
                            numberOfMatches += 1;
                    }
                }
                sw.Stop();
                end = DateTime.Now;
                Console.WriteLine("Finished at: " + end.ToLongTimeString());
                Console.WriteLine("Time to run: " + sw.Elapsed.ToString("mm\\:ss\\.fffffff"));
                Console.WriteLine("Number of Matches: " + numberOfMatches);
                Console.WriteLine();

                //Test using the ToUpper and ToLower methods only if we don't care about case.
                if (!caseSensitive)
                {
                    Thread.Sleep(1000);
                    numberOfMatches = 0;

                    Console.WriteLine("Starting ToLower(): " + DateTime.Now.ToLongTimeString());
                    sw.Restart();
                    for (int x = 0; x < numberOfStringsToCompare; x++)
                    {
                        if (stringsWeWantToSeeIfMatches[x].ToLower() == stringsWeAreComparingAgainst[x].ToLower())
                            numberOfMatches += 1;
                    }
                    sw.Stop();
                    end = DateTime.Now;
                    Console.WriteLine("Finished at: " + end.ToLongTimeString());
                    Console.WriteLine("Time to run: " + sw.Elapsed.ToString("mm\\:ss\\.fffffff"));
                    Console.WriteLine("Number of Matches: " + numberOfMatches);
                    Console.WriteLine();

                    Thread.Sleep(1000);
                    numberOfMatches = 0;

                    Console.WriteLine("Starting ToUpper(): " + DateTime.Now.ToLongTimeString());
                    sw.Restart();
                    for (int x = 0; x < numberOfStringsToCompare; x++)
                    {
                        if (stringsWeWantToSeeIfMatches[x].ToUpper() == stringsWeAreComparingAgainst[x].ToUpper())
                            numberOfMatches += 1;
                    }
                    sw.Stop();
                    end = DateTime.Now;
                    Console.WriteLine("Finished at: " + end.ToLongTimeString());
                    Console.WriteLine("Time to run: " + sw.Elapsed.ToString("mm\\:ss\\.fffffff"));
                    Console.WriteLine("Number of Matches: " + numberOfMatches);
                    Console.WriteLine();
                }

                Thread.Sleep(1000);
                numberOfMatches = 0;

                //check char by char
                //again, put case check outside loop to not affect run time
                if (caseSensitive)
                {
                    Console.WriteLine("Starting char by char Case Sensitive: " + DateTime.Now.ToLongTimeString());
                    sw.Restart();
                    for (int x = 0; x < numberOfStringsToCompare; x++)
                    {
                        isDifferent = false;
                        if (stringsWeAreComparingAgainst[x].Length != stringsWeWantToSeeIfMatches[x].Length)
                        {
                            isDifferent = true;
                            continue;
                        }
                        else
                        {
                            for (int y = 0; y < stringsWeWantToSeeIfMatches[x].Length; y++)
                            {
                                if (stringsWeWantToSeeIfMatches[x][y] != stringsWeAreComparingAgainst[x][y])
                                {
                                    isDifferent = true;
                                    break;
                                }
                            }
                            if (!isDifferent)
                                numberOfMatches += 1;
                        }
                    }
                }
                else
                {
                    Console.WriteLine("Starting char by char Case Insensitive: " + DateTime.Now.ToLongTimeString());
                    sw.Restart();
                    for (int x = 0; x < numberOfStringsToCompare; x++)
                    {
                        isDifferent = false;
                        if (stringsWeAreComparingAgainst[x].Length != stringsWeWantToSeeIfMatches[x].Length)
                        {
                            isDifferent = true;
                            continue;
                        }
                        else
                        {
                            for (int y = 0; y < stringsWeWantToSeeIfMatches[x].Length; y++)
                            {
                                if (char.ToUpperInvariant(stringsWeWantToSeeIfMatches[x][y]) != char.ToUpperInvariant(stringsWeAreComparingAgainst[x][y]))
                                {
                                    isDifferent = true;
                                    break;
                                }
                            }
                            if (!isDifferent)
                                numberOfMatches += 1;
                        }
                    }
                }
                sw.Stop();
                end = DateTime.Now;
                Console.WriteLine("Finished at: " + end.ToLongTimeString());
                Console.WriteLine("Time to run: " + sw.Elapsed.ToString("mm\\:ss\\.fffffff"));
                Console.WriteLine("Number of Matches: " + numberOfMatches);
                Console.WriteLine();

                //use byte arrays method
                //bytes are case sensitive so there will be less matches
                Thread.Sleep(1000);
                numberOfMatches = 0;

                Console.WriteLine("Starting Byte Arrays : " + DateTime.Now.ToLongTimeString());
                sw.Restart();
                //convert each string to a char[] and perform an intersect to see if equal
                for (int x = 0; x < numberOfStringsToCompare; x++)
                {
                    b1 = Encoding.Unicode.GetBytes(stringsWeWantToSeeIfMatches[x]);
                    b2 = Encoding.Unicode.GetBytes(stringsWeAreComparingAgainst[x]);
                    if (b1.SequenceEqual(b2))
                        numberOfMatches += 1;
                }
                sw.Stop();
                end = DateTime.Now;
                Console.WriteLine("Finished at: " + end.ToLongTimeString());
                Console.WriteLine("Time to run: " + sw.Elapsed.ToString("mm\\:ss\\.fffffff"));
                Console.WriteLine("Number of Matches: " + numberOfMatches);
                Console.WriteLine();

                //use a dictionary to see if the key exists
                //it is case sensitive so there will be less matches
                Thread.Sleep(1000);
                numberOfMatches = 0;

                Console.WriteLine("Starting Dictionary : " + DateTime.Now.ToLongTimeString());
                sw.Restart();
                for (int x = 0; x < numberOfStringsToCompare; x++)
                {
                    if (d.ContainsKey(stringsWeWantToSeeIfMatches[x]))
                    {
                        numberOfMatches += 1;
                    }
                }
                sw.Stop();
                end = DateTime.Now;
                Console.WriteLine("Finished at: " + end.ToLongTimeString());
                Console.WriteLine("Time to run: " + sw.Elapsed.ToString("mm\\:ss\\.fffffff"));
                Console.WriteLine("Number of Matches: " + numberOfMatches);
                Console.WriteLine();

                //use a hashset to see if the key exists
                //it is case sensitive so there will be less matches
                Thread.Sleep(1000);
                numberOfMatches = 0;

                Console.WriteLine("Starting Hashset : " + DateTime.Now.ToLongTimeString());
                sw.Restart();
                for (int x = 0; x < numberOfStringsToCompare; x++)
                {
                    if (hs.Contains(stringsWeWantToSeeIfMatches[x]))
                    {
                        numberOfMatches += 1;
                    }
                }
                sw.Stop();
                end = DateTime.Now;
                Console.WriteLine("Finished at: " + end.ToLongTimeString());
                Console.WriteLine("Time to run: " + sw.Elapsed.ToString("mm\\:ss\\.fffffff"));
                Console.WriteLine("Number of Matches: " + numberOfMatches);
                Console.WriteLine();

                Thread.Sleep(1000);
                numberOfMatches = 0;

                //IndexOf method for whole length of string
                if (caseSensitive)
                {
                    Console.WriteLine("Starting IndexOf : " + DateTime.Now.ToLongTimeString());
                    sw.Restart();
                    for (int x = 0; x < numberOfStringsToCompare; x++)
                    {
                        if (stringsWeAreComparingAgainst[x].IndexOf(stringsWeWantToSeeIfMatches[x], 0, stringsWeWantToSeeIfMatches[x].Length) == 0)
                            numberOfMatches += 1;
                    }
                    sw.Stop();
                    end = DateTime.Now;
                    Console.WriteLine("Finished at: " + end.ToLongTimeString());
                    Console.WriteLine("Time to run: " + sw.Elapsed.ToString("mm\\:ss\\.fffffff"));
                    Console.WriteLine("Number of Matches: " + numberOfMatches);
                    Console.WriteLine();
                }
                else
                {   //have to do some mods to do a case insensitive comparison
                    Console.WriteLine("Starting IndexOf : " + DateTime.Now.ToLongTimeString());
                    sw.Restart();
                    for (int x = 0; x < numberOfStringsToCompare; x++)
                    {
                        if (stringsWeAreComparingAgainst[x].IndexOf(stringsWeWantToSeeIfMatches[x], 0, stringsWeWantToSeeIfMatches[x].Length, StringComparison.OrdinalIgnoreCase) == 0)
                            numberOfMatches += 1;
                    }
                    sw.Stop();
                    end = DateTime.Now;
                    Console.WriteLine("Finished at: " + end.ToLongTimeString());
                    Console.WriteLine("Time to run: " + sw.Elapsed.ToString("mm\\:ss\\.fffffff"));
                    Console.WriteLine("Number of Matches: " + numberOfMatches);
                    Console.WriteLine();
                }

                Thread.Sleep(1000);
                numberOfMatches = 0;

                //Common method
                if (caseSensitive)
                {
                    Console.WriteLine("Starting CommonMethod Case Sensitive: " + DateTime.Now.ToLongTimeString());
                    sw.Restart();
                    for (int x = 0; x < numberOfStringsToCompare; x++)
                    {
                        numberOfMatches += ((stringsWeAreComparingAgainst[x].Length - stringsWeAreComparingAgainst[x].Replace(stringsWeWantToSeeIfMatches[x], String.Empty).Length) / stringsWeWantToSeeIfMatches[x].Length > 0 ? 1 : 0);
                    }
                    sw.Stop();
                    end = DateTime.Now;
                    Console.WriteLine("Finished at: " + end.ToLongTimeString());
                    Console.WriteLine("Time to run: " + sw.Elapsed.ToString("mm\\:ss\\.fffffff"));
                    Console.WriteLine("Number of Matches: " + numberOfMatches);
                    Console.WriteLine();
                }
                else
                {
                    Console.WriteLine("Starting CommonMethod Case Insensitive: " + DateTime.Now.ToLongTimeString());
                    sw.Restart();
                    for (int x = 0; x < numberOfStringsToCompare; x++)
                    {
                        numberOfMatches += ((stringsWeAreComparingAgainst[x].Length - stringsWeAreComparingAgainst[x].ToLower().Replace(stringsWeWantToSeeIfMatches[x].ToLower(), String.Empty).Length) / stringsWeWantToSeeIfMatches[x].Length > 0 ? 1 : 0);
                    }
                    sw.Stop();
                    end = DateTime.Now;
                    Console.WriteLine("Finished at: " + end.ToLongTimeString());
                    Console.WriteLine("Time to run: " + sw.Elapsed.ToString("mm\\:ss\\.fffffff"));
                    Console.WriteLine("Number of Matches: " + numberOfMatches);
                    Console.WriteLine();
                }

                Thread.Sleep(1000);
                numberOfMatches = 0;

                //SequenceEqual method
                if (caseSensitive)
                {
                    Console.WriteLine("Starting SequenceEqual Case Sensitive: " + DateTime.Now.ToLongTimeString());
                    sw.Restart();
                    for (int x = 0; x < numberOfStringsToCompare; x++)
                    {
                        c1 = stringsWeWantToSeeIfMatches[x].ToCharArray();
                        c2 = stringsWeAreComparingAgainst[x].ToCharArray();
                        if (c1.SequenceEqual(c2))
                            numberOfMatches += 1;
                    }
                    sw.Stop();
                    end = DateTime.Now;
                    Console.WriteLine("Finished at: " + end.ToLongTimeString());
                    Console.WriteLine("Time to run: " + sw.Elapsed.ToString("mm\\:ss\\.fffffff"));
                    Console.WriteLine("Number of Matches: " + numberOfMatches);
                    Console.WriteLine();
                }
                else
                {   //have to do some mods to do a case insensitive comparison
                    Console.WriteLine("Starting SequenceEqual Case Insensitive: " + DateTime.Now.ToLongTimeString());
                    sw.Restart();
                    for (int x = 0; x < numberOfStringsToCompare; x++)
                    {
                        s1 = new[] { stringsWeWantToSeeIfMatches[x] };
                        s2 = new[] { stringsWeAreComparingAgainst[x] };
                        if (s1.SequenceEqual(s2, StringComparer.OrdinalIgnoreCase))
                            numberOfMatches += 1;
                    }
                    sw.Stop();
                    end = DateTime.Now;
                    Console.WriteLine("Finished at: " + end.ToLongTimeString());
                    Console.WriteLine("Time to run: " + sw.Elapsed.ToString("mm\\:ss\\.fffffff"));
                    Console.WriteLine("Number of Matches: " + numberOfMatches);
                    Console.WriteLine();
                }

                Console.WriteLine();
                Console.WriteLine("###########################################################");

            }
            catch (Exception e)
            {
                Console.WriteLine("An EXCEPTION occurred as follows: " + Environment.NewLine + Environment.NewLine + e.ToString());
            }
            finally
            {
                //Clean up
                if (stringsWeAreComparingAgainst != null)
                {
                    Array.Clear(stringsWeAreComparingAgainst, 0, stringsWeAreComparingAgainst.Length);
                    stringsWeAreComparingAgainst = null;
                }
                if (stringsWeWantToSeeIfMatches != null)
                {
                    Array.Clear(stringsWeWantToSeeIfMatches, 0, stringsWeWantToSeeIfMatches.Length);
                    stringsWeWantToSeeIfMatches = null;
                }
                if (b1 != null)
                {
                    Array.Clear(b1, 0, b1.Length);
                    b1 = null;
                }
                if (b2 != null)
                {
                    Array.Clear(b2, 0, b2.Length);
                    b2 = null;
                }
                if (c1 != null)
                {
                    Array.Clear(c1, 0, c1.Length);
                    c1 = null;
                }
                if (c2 != null)
                {
                    Array.Clear(c2, 0, c2.Length);
                    c2 = null;
                }
                if (s1 != null)
                {
                    Array.Clear(s1, 0, s1.Length);
                    s1 = null;
                }
                if (s2 != null)
                {
                    Array.Clear(s2, 0, s2.Length);
                    s2 = null;
                }
                hs.Clear();
                hs = null;
                d.Clear();
                d = null;
                GC.Collect();
            }
        }
    
    }
}

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using System;

using System.Collections.Generic;

using System.Collections;

using System.Collections.Concurrent;

using System.IO;

using System.Linq;

using System.Text;

using System.Text.RegularExpressions;

using System.Threading.Tasks;

using System.Threading;

namespace TestApplication

{

class Program

{

static void Main(string[] args)

{

DateTime end;

DateTime start = DateTime.Now;

Console.WriteLine("### Overall Start Time: " + start.ToLongTimeString());

Console.WriteLine();

#region CompareTwoStrings

FastestWayToCompareTwoStrings(100, true);

FastestWayToCompareTwoStrings(1000, true);

FastestWayToCompareTwoStrings(10000, true);

FastestWayToCompareTwoStrings(100000, true);

FastestWayToCompareTwoStrings(1000000, true);

FastestWayToCompareTwoStrings(100, false);

FastestWayToCompareTwoStrings(1000, false);

FastestWayToCompareTwoStrings(10000, false);

FastestWayToCompareTwoStrings(100000, false);

FastestWayToCompareTwoStrings(1000000, false);

#endregion

end = DateTime.Now;

Console.WriteLine();

Console.WriteLine("### Overall End Time: " + end.ToLongTimeString());

Console.WriteLine("### Overall Run Time: " + (end - start));

Console.WriteLine();

Console.WriteLine("Hit Enter to Exit");

Console.ReadLine();

}

//####################################################

//Which way is faster to compare to string?

static void FastestWayToCompareTwoStrings(int numberOfStringsToCompare, bool caseSensitive)

{

Stopwatch sw = new Stopwatch();

DateTime end = DateTime.Now;

string[] stringsWeAreComparingAgainst = new String[numberOfStringsToCompare];

string[] stringsWeWantToSeeIfMatches = new String[numberOfStringsToCompare];

int numberOfMatches = 0;

int z = 4;

bool isDifferent = false;

byte[] b1 = null;

byte[] b2 = null;

char[] c1 = null;

char[] c2 = null;

string[] s1 = null;

string[] s2 = null;

HashSet<string> hs = new HashSet<string>();

Dictionary<string, string> d = new Dictionary<string, string>(numberOfStringsToCompare);

Console.WriteLine("######## " + System.Reflection.MethodBase.GetCurrentMethod().Name);

Console.WriteLine("######## Number of strings to compare: " + numberOfStringsToCompare.ToString("#,##0"));

Console.WriteLine("######## Case Sensitive: " + caseSensitive.ToString());

Console.WriteLine("###########################################################");

Console.WriteLine();

try

{

//set up the array of strings to use

Console.WriteLine("###########################################################");

Console.WriteLine("Starting creating string arrays with " + numberOfStringsToCompare.ToString("#,##0") + " strings");

Console.WriteLine("###########################################################");

for (int x = 0; x < numberOfStringsToCompare; x++)

{

//Use the generate password function so we can easily vary the length of the strings and the chars within

stringsWeAreComparingAgainst[x] = System.Web.Security.Membership.GeneratePassword(z, z % 4);

if (x % 3 == 0)

{

//to ensure we have some matches

stringsWeWantToSeeIfMatches[x] = stringsWeAreComparingAgainst[x];

}

else

{

stringsWeWantToSeeIfMatches[x] = System.Web.Security.Membership.GeneratePassword(z, z % 4);

}

if (!d.ContainsKey(stringsWeAreComparingAgainst[x]))

{

d.Add(stringsWeAreComparingAgainst[x], string.Empty);

hs.Add(stringsWeAreComparingAgainst[x]);

}

if (z > 25) { z = 4; } else { z += 1; }

}

Console.WriteLine("Completed creating string arrays with " + numberOfStringsToCompare.ToString("#,##0") + " strings");

Console.WriteLine("###########################################################");

// using the ==

//it's case sensitive so there will be less matches

Thread.Sleep(1000);

numberOfMatches = 0;

if (caseSensitive)

{

Console.WriteLine("Starting == Case Sensitive: " + DateTime.Now.ToLongTimeString());

sw.Restart();

for (int x = 0; x < numberOfStringsToCompare; x++)

{

if (stringsWeWantToSeeIfMatches[x] == stringsWeAreComparingAgainst[x])

numberOfMatches += 1;

}

sw.Stop();

}

else

{

Console.WriteLine("Starting == Case Insensitive: " + DateTime.Now.ToLongTimeString());

sw.Restart();

for (int x = 0; x < numberOfStringsToCompare; x++)

{

if (stringsWeWantToSeeIfMatches[x].ToLower() == stringsWeAreComparingAgainst[x].ToLower())

numberOfMatches += 1;

}

sw.Stop();

}

end = DateTime.Now;

Console.WriteLine("Finished at: " + end.ToLongTimeString());

Console.WriteLine("Time to run: " + sw.Elapsed.ToString("mm\\:ss\\.fffffff"));

Console.WriteLine("Number of Matches: " + numberOfMatches);

Console.WriteLine();

Thread.Sleep(1000);

numberOfMatches = 0;

//String.Compare

Console.WriteLine("Starting String.Compare: " + DateTime.Now.ToLongTimeString());

sw.Restart();

for (int x = 0; x < numberOfStringsToCompare; x++)

{

if (string.Compare(stringsWeWantToSeeIfMatches[x], stringsWeAreComparingAgainst[x], caseSensitive) == 0)

numberOfMatches += 1;

}

sw.Stop();

end = DateTime.Now;

Console.WriteLine("Finished at: " + end.ToLongTimeString());

Console.WriteLine("Time to run: " + sw.Elapsed.ToString("mm\\:ss\\.fffffff"));

Console.WriteLine("Number of Matches: " + numberOfMatches);

Console.WriteLine();

Thread.Sleep(1000);

numberOfMatches = 0;

//String.CompareOrdinal

Console.WriteLine("Starting String.CompareOrdinal: " + DateTime.Now.ToLongTimeString());

sw.Restart();

for (int x = 0; x < numberOfStringsToCompare; x++)

{

if (string.CompareOrdinal(stringsWeWantToSeeIfMatches[x], stringsWeAreComparingAgainst[x]) == 0)

numberOfMatches += 1;

}

sw.Stop();

end = DateTime.Now;

Console.WriteLine("Finished at: " + end.ToLongTimeString());

Console.WriteLine("Time to run: " + sw.Elapsed.ToString("mm\\:ss\\.fffffff"));

Console.WriteLine("Number of Matches: " + numberOfMatches);

Console.WriteLine();

Thread.Sleep(1000);

numberOfMatches = 0;

//String.Equals

//put the if statement outside the for-loops so it doesn't impact on run time

if (caseSensitive)

{

Console.WriteLine("Starting String.Equals Case Sensitive: " + DateTime.Now.ToLongTimeString());

sw.Restart();

for (int x = 0; x < numberOfStringsToCompare; x++)

{

if (String.Equals(stringsWeWantToSeeIfMatches[x], stringsWeAreComparingAgainst[x]))

numberOfMatches += 1;

}

else

{

Console.WriteLine("Starting String.Equals Case Insensitive: " + DateTime.Now.ToLongTimeString());

sw.Restart();

for (int x = 0; x < numberOfStringsToCompare; x++)

{

if (String.Equals(stringsWeWantToSeeIfMatches[x], stringsWeAreComparingAgainst[x], StringComparison.OrdinalIgnoreCase))

numberOfMatches += 1;

}

sw.Stop();

end = DateTime.Now;

Console.WriteLine("Finished at: " + end.ToLongTimeString());

Console.WriteLine("Time to run: " + sw.Elapsed.ToString("mm\\:ss\\.fffffff"));

Console.WriteLine("Number of Matches: " + numberOfMatches);

Console.WriteLine();

//Test using the ToUpper and ToLower methods only if we don't care about case.

if (!caseSensitive)

{

Thread.Sleep(1000);

numberOfMatches = 0;

Console.WriteLine("Starting ToLower(): " + DateTime.Now.ToLongTimeString());

sw.Restart();

for (int x = 0; x < numberOfStringsToCompare; x++)

{

if (stringsWeWantToSeeIfMatches[x].ToLower() == stringsWeAreComparingAgainst[x].ToLower())

numberOfMatches += 1;

}

sw.Stop();

end = DateTime.Now;

Console.WriteLine("Finished at: " + end.ToLongTimeString());

Console.WriteLine("Time to run: " + sw.Elapsed.ToString("mm\\:ss\\.fffffff"));

Console.WriteLine("Number of Matches: " + numberOfMatches);

Console.WriteLine();

Thread.Sleep(1000);

numberOfMatches = 0;

Console.WriteLine("Starting ToUpper(): " + DateTime.Now.ToLongTimeString());

sw.Restart();

for (int x = 0; x < numberOfStringsToCompare; x++)

{

if (stringsWeWantToSeeIfMatches[x].ToUpper() == stringsWeAreComparingAgainst[x].ToUpper())

numberOfMatches += 1;

}

sw.Stop();

end = DateTime.Now;

Console.WriteLine("Finished at: " + end.ToLongTimeString());

Console.WriteLine("Time to run: " + sw.Elapsed.ToString("mm\\:ss\\.fffffff"));

Console.WriteLine("Number of Matches: " + numberOfMatches);

Console.WriteLine();

}

Thread.Sleep(1000);

numberOfMatches = 0;

//check char by char

//again, put case check outside loop to not affect run time

if (caseSensitive)

{

Console.WriteLine("Starting char by char Case Sensitive: " + DateTime.Now.ToLongTimeString());

sw.Restart();

for (int x = 0; x < numberOfStringsToCompare; x++)

{

isDifferent = false;

if (stringsWeAreComparingAgainst[x].Length != stringsWeWantToSeeIfMatches[x].Length)

{

isDifferent = true;

continue;

}

else

{

for (int y = 0; y < stringsWeWantToSeeIfMatches[x].Length; y++)

{

if (stringsWeWantToSeeIfMatches[x][y] != stringsWeAreComparingAgainst[x][y])

{

isDifferent = true;

break;

}

if (!isDifferent)

numberOfMatches += 1;

}

else

{

Console.WriteLine("Starting char by char Case Insensitive: " + DateTime.Now.ToLongTimeString());

sw.Restart();

for (int x = 0; x < numberOfStringsToCompare; x++)

{

isDifferent = false;

if (stringsWeAreComparingAgainst[x].Length != stringsWeWantToSeeIfMatches[x].Length)

{

isDifferent = true;

continue;

}

else

{

for (int y = 0; y < stringsWeWantToSeeIfMatches[x].Length; y++)

{

if (char.ToUpperInvariant(stringsWeWantToSeeIfMatches[x][y]) != char.ToUpperInvariant(stringsWeAreComparingAgainst[x][y]))

{

isDifferent = true;

break;

}

if (!isDifferent)

numberOfMatches += 1;

}

sw.Stop();

end = DateTime.Now;

Console.WriteLine("Finished at: " + end.ToLongTimeString());

Console.WriteLine("Time to run: " + sw.Elapsed.ToString("mm\\:ss\\.fffffff"));

Console.WriteLine("Number of Matches: " + numberOfMatches);

Console.WriteLine();

//use byte arrays method

//bytes are case sensitive so there will be less matches

Thread.Sleep(1000);

numberOfMatches = 0;

Console.WriteLine("Starting Byte Arrays : " + DateTime.Now.ToLongTimeString());

sw.Restart();

//convert each string to a char[] and perform an intersect to see if equal

for (int x = 0; x < numberOfStringsToCompare; x++)

{

b1 = Encoding.Unicode.GetBytes(stringsWeWantToSeeIfMatches[x]);

b2 = Encoding.Unicode.GetBytes(stringsWeAreComparingAgainst[x]);

if (b1.SequenceEqual(b2))

numberOfMatches += 1;

}

sw.Stop();

end = DateTime.Now;

Console.WriteLine("Finished at: " + end.ToLongTimeString());

Console.WriteLine("Time to run: " + sw.Elapsed.ToString("mm\\:ss\\.fffffff"));

Console.WriteLine("Number of Matches: " + numberOfMatches);

Console.WriteLine();

//use a dictionary to see if the key exists

//it is case sensitive so there will be less matches

Thread.Sleep(1000);

numberOfMatches = 0;

Console.WriteLine("Starting Dictionary : " + DateTime.Now.ToLongTimeString());

sw.Restart();

for (int x = 0; x < numberOfStringsToCompare; x++)

{

if (d.ContainsKey(stringsWeWantToSeeIfMatches[x]))

{

numberOfMatches += 1;

}

sw.Stop();

end = DateTime.Now;

Console.WriteLine("Finished at: " + end.ToLongTimeString());

Console.WriteLine("Time to run: " + sw.Elapsed.ToString("mm\\:ss\\.fffffff"));

Console.WriteLine("Number of Matches: " + numberOfMatches);

Console.WriteLine();

//use a hashset to see if the key exists

//it is case sensitive so there will be less matches

Thread.Sleep(1000);

numberOfMatches = 0;

Console.WriteLine("Starting Hashset : " + DateTime.Now.ToLongTimeString());

sw.Restart();

for (int x = 0; x < numberOfStringsToCompare; x++)

{

if (hs.Contains(stringsWeWantToSeeIfMatches[x]))

{

numberOfMatches += 1;

}

sw.Stop();

end = DateTime.Now;

Console.WriteLine("Finished at: " + end.ToLongTimeString());

Console.WriteLine("Time to run: " + sw.Elapsed.ToString("mm\\:ss\\.fffffff"));

Console.WriteLine("Number of Matches: " + numberOfMatches);

Console.WriteLine();

Thread.Sleep(1000);

numberOfMatches = 0;

//IndexOf method for whole length of string

if (caseSensitive)

{

Console.WriteLine("Starting IndexOf : " + DateTime.Now.ToLongTimeString());

sw.Restart();

for (int x = 0; x < numberOfStringsToCompare; x++)

{

if (stringsWeAreComparingAgainst[x].IndexOf(stringsWeWantToSeeIfMatches[x], 0, stringsWeWantToSeeIfMatches[x].Length) == 0)

numberOfMatches += 1;

}

sw.Stop();

end = DateTime.Now;

Console.WriteLine("Finished at: " + end.ToLongTimeString());

Console.WriteLine("Time to run: " + sw.Elapsed.ToString("mm\\:ss\\.fffffff"));

Console.WriteLine("Number of Matches: " + numberOfMatches);

Console.WriteLine();

}

else

{ //have to do some mods to do a case insensitive comparison

Console.WriteLine("Starting IndexOf : " + DateTime.Now.ToLongTimeString());

sw.Restart();

for (int x = 0; x < numberOfStringsToCompare; x++)

{

if (stringsWeAreComparingAgainst[x].IndexOf(stringsWeWantToSeeIfMatches[x], 0, stringsWeWantToSeeIfMatches[x].Length, StringComparison.OrdinalIgnoreCase) == 0)

numberOfMatches += 1;

}

sw.Stop();

end = DateTime.Now;

Console.WriteLine("Finished at: " + end.ToLongTimeString());

Console.WriteLine("Time to run: " + sw.Elapsed.ToString("mm\\:ss\\.fffffff"));

Console.WriteLine("Number of Matches: " + numberOfMatches);

Console.WriteLine();

}

Thread.Sleep(1000);

numberOfMatches = 0;

//Common method

if (caseSensitive)

{

Console.WriteLine("Starting CommonMethod Case Sensitive: " + DateTime.Now.ToLongTimeString());

sw.Restart();

for (int x = 0; x < numberOfStringsToCompare; x++)

{

numberOfMatches += ((stringsWeAreComparingAgainst[x].Length - stringsWeAreComparingAgainst[x].Replace(stringsWeWantToSeeIfMatches[x], String.Empty).Length) / stringsWeWantToSeeIfMatches[x].Length > 0 ? 1 : 0);

}

sw.Stop();

end = DateTime.Now;

Console.WriteLine("Finished at: " + end.ToLongTimeString());

Console.WriteLine("Time to run: " + sw.Elapsed.ToString("mm\\:ss\\.fffffff"));

Console.WriteLine("Number of Matches: " + numberOfMatches);

Console.WriteLine();

}

else

{

Console.WriteLine("Starting CommonMethod Case Insensitive: " + DateTime.Now.ToLongTimeString());

sw.Restart();

for (int x = 0; x < numberOfStringsToCompare; x++)

{

numberOfMatches += ((stringsWeAreComparingAgainst[x].Length - stringsWeAreComparingAgainst[x].ToLower().Replace(stringsWeWantToSeeIfMatches[x].ToLower(), String.Empty).Length) / stringsWeWantToSeeIfMatches[x].Length > 0 ? 1 : 0);

}

sw.Stop();

end = DateTime.Now;

Console.WriteLine("Finished at: " + end.ToLongTimeString());

Console.WriteLine("Time to run: " + sw.Elapsed.ToString("mm\\:ss\\.fffffff"));

Console.WriteLine("Number of Matches: " + numberOfMatches);

Console.WriteLine();

}

Thread.Sleep(1000);

numberOfMatches = 0;

//SequenceEqual method

if (caseSensitive)

{

Console.WriteLine("Starting SequenceEqual Case Sensitive: " + DateTime.Now.ToLongTimeString());

sw.Restart();

for (int x = 0; x < numberOfStringsToCompare; x++)

{

c1 = stringsWeWantToSeeIfMatches[x].ToCharArray();

c2 = stringsWeAreComparingAgainst[x].ToCharArray();

if (c1.SequenceEqual(c2))

numberOfMatches += 1;

}

sw.Stop();

end = DateTime.Now;

Console.WriteLine("Finished at: " + end.ToLongTimeString());

Console.WriteLine("Time to run: " + sw.Elapsed.ToString("mm\\:ss\\.fffffff"));

Console.WriteLine("Number of Matches: " + numberOfMatches);

Console.WriteLine();

}

else

{ //have to do some mods to do a case insensitive comparison

Console.WriteLine("Starting SequenceEqual Case Insensitive: " + DateTime.Now.ToLongTimeString());

sw.Restart();

for (int x = 0; x < numberOfStringsToCompare; x++)

{

s1 = new[] { stringsWeWantToSeeIfMatches[x] };

s2 = new[] { stringsWeAreComparingAgainst[x] };

if (s1.SequenceEqual(s2, StringComparer.OrdinalIgnoreCase))

numberOfMatches += 1;

}

sw.Stop();

end = DateTime.Now;

Console.WriteLine("Finished at: " + end.ToLongTimeString());

Console.WriteLine("Time to run: " + sw.Elapsed.ToString("mm\\:ss\\.fffffff"));

Console.WriteLine("Number of Matches: " + numberOfMatches);

Console.WriteLine();

}

Console.WriteLine();

Console.WriteLine("###########################################################");

}

catch (Exception e)

{

Console.WriteLine("An EXCEPTION occurred as follows: " + Environment.NewLine + Environment.NewLine + e.ToString());

}

finally

{

//Clean up

if (stringsWeAreComparingAgainst != null)

{

Array.Clear(stringsWeAreComparingAgainst, 0, stringsWeAreComparingAgainst.Length);

stringsWeAreComparingAgainst = null;

}

if (stringsWeWantToSeeIfMatches != null)

{

Array.Clear(stringsWeWantToSeeIfMatches, 0, stringsWeWantToSeeIfMatches.Length);

stringsWeWantToSeeIfMatches = null;

}

if (b1 != null)

{

Array.Clear(b1, 0, b1.Length);

b1 = null;

}

if (b2 != null)

{

Array.Clear(b2, 0, b2.Length);

b2 = null;

}

if (c1 != null)

{

Array.Clear(c1, 0, c1.Length);

c1 = null;

}

if (c2 != null)

{

Array.Clear(c2, 0, c2.Length);

c2 = null;

}

if (s1 != null)

{

Array.Clear(s1, 0, s1.Length);

s1 = null;

}

if (s2 != null)

{

Array.Clear(s2, 0, s2.Length);

s2 = null;

}

hs.Clear();

hs = null;

d.Clear();

d = null;

GC.Collect();

}

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Fastest Way to Compare Strings in C# .Net

The Background:

The Gist of it All:

Off To The Races!

The Results:

In Summary:

The Code:

David Lozinski