How to: Search Strings Using String Methods (C# Programming Guide)

 

Updated: July 20, 2015

The string type, which is an alias for the System.String class, provides a number of useful methods for searching the contents of a string.

The following example uses the IndexOf, LastIndexOf, StartsWith, and EndsWith methods to search the strings.

    class StringSearch
    {
        static void Main()
        {
            string str = "Extension methods have all the capabilities of regular static methods.";

            // Write the string and include the quotation marks.
            System.Console.WriteLine("\"{0}\"", str);

            // Simple comparisons are always case sensitive!
            bool test1 = str.StartsWith("extension");
            System.Console.WriteLine("Starts with \"extension\"? {0}", test1);

            // For user input and strings that will be displayed to the end user, 
            // use the StringComparison parameter on methods that have it to specify how to match strings.
            bool test2 = str.StartsWith("extension", System.StringComparison.CurrentCultureIgnoreCase);
            System.Console.WriteLine("Starts with \"extension\"? {0} (ignoring case)", test2);

            bool test3 = str.EndsWith(".", System.StringComparison.CurrentCultureIgnoreCase);
            System.Console.WriteLine("Ends with '.'? {0}", test3);

            // This search returns the substring between two strings, so 
            // the first index is moved to the character just after the first string.
            int first = str.IndexOf("methods") + "methods".Length;
            int last = str.LastIndexOf("methods");
            string str2 = str.Substring(first, last - first);
            System.Console.WriteLine("Substring between \"methods\" and \"methods\": '{0}'", str2);

            // Keep the console window open in debug mode
            System.Console.WriteLine("Press any key to exit.");
            System.Console.ReadKey();
        }
    }
    /*
    Output:
    "Extension methods have all the capabilities of regular static methods."
    Starts with "extension"? False
    Starts with "extension"? True (ignoring case)
    Ends with '.'? True
    Substring between "methods" and "methods": ' have all the capabilities of regular static '
    Press any key to exit.     
    */

C# Programming Guide
Strings
How to: Search Strings Using Regular Expressions
LINQ and Strings

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