class StringSearch
{
static void Main()
{
string str = "A silly sentence used for silly purposes.";
System.Console.WriteLine("'{0}'",str);
bool test1 = str.StartsWith("a silly");
System.Console.WriteLine("starts with 'a silly'? {0}", test1);
bool test2 = str.StartsWith("a silly", System.StringComparison.OrdinalIgnoreCase);
System.Console.WriteLine("starts with 'a silly'? {0} (ignoring case)", test2);
bool test3 = str.EndsWith(".");
System.Console.WriteLine("ends with '.'? {0}", test3);
int first = str.IndexOf("silly");
int last = str.LastIndexOf("silly");
string str2 = str.Substring(first, last - first);
System.Console.WriteLine("between two 'silly' words: '{0}'", str2);
}
}

输出

'A silly sentence used for silly purposes.'
starts with 'a silly'? False
starts with 'a silly'? True (ignore case)
ends with '.'? True
between two 'silly' words: 'silly sentence used for '