C#中查询字符串中是否包含指定字符/串,使用IndexOf还是Contains?这是一个很常见的命题,以前也没有注意,今天QQ群里有人提起,于是就做了下试验,代码如下:
using System; using System.Diagnostics; namespace ConsoleApplication1 { class Program { private const int N = 10000000; private static Stopwatch watch = new Stopwatch(); static void Main(string[] args) { string source = "abcdefghijklmnopqrstuvwxyz0123456789C#" + "中查询字符串中是否包含指定字符/串,使用IndexOf还是Contains?.uonun"; string target = "a"; Console.WriteLine("目标为第一个字符时:"); TestContains(source, target); TestIndexOf(source, target); Console.WriteLine(); Console.WriteLine("目标为中部某个字符时:"); target = "中"; TestContains(source, target); TestIndexOf(source, target); Console.WriteLine(); Console.WriteLine("目标为最后一个字符时:"); target = "u"; TestContains(source, target); TestIndexOf(source, target); Console.WriteLine("执行完毕,按任意键退出..."); Console.ReadKey(); } private static void TestIndexOf(string source, string target) { watch.Reset(); watch.Start(); for (int i = 0;i < N;i++) { source.IndexOf(target); } watch.Stop(); Console.WriteLine("IndexOf: " + watch.ElapsedMilliseconds.ToString() + "ms"); return; } private static void TestContains(string source, string target) { watch.Reset(); watch.Start(); for (int i = 0;i < N;i++) { source.Contains(target); } watch.Stop(); Console.WriteLine("Contains: " + watch.ElapsedMilliseconds.ToString() + "ms"); return; } } }
得到的结果是:
目标为第一个字符时:
Contains: 973ms
IndexOf: 1343ms
目标为中部某个字符时:
Contains: 1813ms
IndexOf: 8602ms
目标为最后一个字符时:
Contains: 1433ms
IndexOf: 5094ms
执行完毕,按任意键退出...
可以看出,使用Contains方法的效率比IndexOf的效率高很多。