string[] arrstr2 = str.Replace("[111cn.net]", "$").Split('$');

string s="abcdeabcdeabcde";
string[] sArray=s.Split('c');
foreach(string i in sArray)
Console.WriteLine(i.ToString());

輸出下面的結果:
ab
deab
deab
de

string s="abcdeabcdeabcde"
string[] sArray1=s.Split(new char[3]{'c','d','e'});
foreach(string i in sArray1)
Console.WriteLine(i.ToString());

輸出下面的結果：
ab
ab
ab

using System.Text.RegularExPRessions;

string content="agcsmallmacsmallgggsmallytx";
string[]resultString=Regex.Split(content,"small",RegexOptions.IgnoreCase)
foreach(string i in resultString)
Console.WriteLine(i.ToString());