C#(a.cs)

using System;public class Test
{public void Middle(string start, string end){string pat1 = string.Format("(?<={0}).*(?={1})", start, end);Console.WriteLine(pat1);string pat2 = string.Format("(?<={{0}}).*(?={{1}})", start, end);Console.WriteLine(pat2);string pat3 = string.Format("(?<={{{0}}}).*(?={{{1}}})", start, end);Console.WriteLine(pat3);}public static void Main(string[] args){string start = "12";string end = "35";Test t = new Test();t.Middle(start, end);}
}

编译运行:

E:\>csc a.cs
Microsoft(R) Visual C# 2010 编译器 4.0.30319.1 版
版权所有(C) Microsoft Corporation。保留所有权利。E:\>a.exe
(?<=12).*(?=35)
(?<={0}).*(?={1})
(?<={12}).*(?={35})E:\>

结论： {{ 得到 { ， }} 得到 }

更多信息可参考：http://msdn.microsoft.com/zh-cn/library/txafckwd.aspx