C# StartsWith and EndsWith String Methods

Use the StartsWith and EndsWith methods on strings. StartsWith compares the first part of strings.

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StartsWith tests the first part of strings. We use it to test the first characters in a string against another string. It is possible to test many strings with the foreach-loop.

With EndsWith, we test the last characters. These two methods provide an easy way to test and match common strings such as URLs. They are used throughout C# programs.

Example, StartsWith. We test URL strings, a common task in web applications. Here we test the "http://www.site.com" string and the "http://site.com" strings. We use StartsWith.If
Tip: In this way, you can use StartsWith for efficient testing of URLs or other strings that have known starts.
C# program that invokes StartsWith method using System; class Program { static void Main() { // The input string. string input = "http://site.com/test.html"; // See if input matches one of these starts. if (input.StartsWith("http://www.site.com") || input.StartsWith("http://site.com")) { // Write to the screen. Console.WriteLine(true); } } } Output True

Foreach, StartsWith. Next, we see that foreach can be used with StartsWith. Here we test elements in a string array against the input string, returning true if there is a match.ForeachArray
C# program that uses StartsWith in loop using System; class Program { static void Main() { // The input string. string input = "http://site.com/test.html"; // The possible matches. string[] m = new string[] { "http://www.site.com", "http://site.com" }; // Loop through each possible match. foreach (string s in m) { if (input.StartsWith(s)) { // Will match second possibility. Console.WriteLine(s); return; } } } } Output http://site.com

EndsWith. This tests the last parts of strings. It finds strings that have a certain ending sequence of characters. EndsWith is a simple way to test for ending substrings.
First: The EndsWith method, like its counterpart the StartsWith method, has three overloaded method signatures.
Here: The first example shows the simplest and first overload, which receives one parameter.
Tip: To use EndsWith, you must pass the string you want to check the ending with as the argument.
Next: An input string is tested for three ends. We detect the ending extension of the URL.
C# program that uses EndsWith using System; class Program { static void Main() { // The input string. string input = "http://site.com"; // Test these endings. string[] arr = new string[] { ".net", ".com", ".org" }; // Loop through and test each string. foreach (string s in arr) { if (input.EndsWith(s)) { Console.WriteLine(s); return; } } } } Output .com

Overloads. EndsWith has some overloads. The first overload is demonstrated above. The second overload accepts a second parameter—a StringComparison enumerated constant.Enum
Tip: You can use StringComparison to specify case-insensitive matching with EndsWith—try OrdinalIgnoreCase.
StringComparison, StringComparer
Finally: The third overload allows more globalization options, which are essential if non-English data will be encountered.

Char test, performance. Consider the StartsWith method: we can duplicate its functionality with individual char tests. In benchmarks, testing chars usually is faster.Char Test

A summary. With StartsWith we can test strings (such as URLs). StartsWith tests the first characters of strings. It returns a bool telling us whether or not the starts match.

EndsWith, meanwhile, tests the end of strings. We used if-statements, and foreach with if-statements, alongside these methods on the string type.


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