如何：使用字符串方法搜索字符串（C# 编程指南）
string 类型（它是 System.String 类的别名）为搜索字符串的内容提供了许多有用的方法。
示例
下面的示例使用 IndexOf、LastIndexOf、StartsWith 和 EndsWith 方法搜素字符串。
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.
*/