c# 查找一个字符串在另一个字符串出现的次数

方法一：

string test = "FF FF FF FF 01 00 82 00 00 A2 00 00 FB 07 FF FF FF FF 01 00 82 00 00 A2 00 00 FB 07";
string r = test.Replace("FF FF FF FF","");
int num = (test.Length - r.Length) /11; //(11是'FF FF FF FF'的长度)
Response.Write(num);

方法二：

string aaa = "aabaabbaabb";
int a=  aaa.Split(new string[] { "aa" }, StringSplitOptions.None).Length-1;