C#截取字符串的几种方式

1.根据单个分隔字符用Split截取
例如
string st="GT123_1";
string[] sArray=st.Split("_");

即可得到sArray[0]="GT123",sArray[1]="1";

//*****************************************/// string[] arr = str.Split("o");

这是一个具有语法错误的语句，Split 的 separator 参数应该是 char[] 或 string[]，不应是字符串。正确的示例：

string str = "technology";
char[] separator = { "o" };
string[] arr = str.Split(separator); //////////////////////////////////////////////////// 2.利用多个字符来分隔字符串
例如
string str = "GTAZB_JiangjBen_123";
string[] sArray = str.Split(new char[2] { "j", "_" });
foreach(string e in sArray)
{
Console.WriteLine(e);
}
得到sArray[0]="GTAZB",sArray[1]="Jiang",sArray[2]="Ben",sArray[3]="123";

3根据字符串或字符串组来截取字符串
例如
string str = "GTAZB_JiangjBen_123";
string[] sArray = str.Split( new string[]{"Ji","jB"}, StringSplitOptions.RemoveEmptyEntries);
foreach(string e in sArray)
{
Console.WriteLine(e);
}
得到sArray[0]="GTAZB_",sArray[1]="ang",sArray[2]="en_123";

4提取字符串中的第i个字符开始的长度为j的字符串；
例如

string str = "GTAZB_JiangjBen_123";
int start=3,length=8; 
Console.WriteLine(str.Substring(start-1, length));
输出得到AZB_Jian。

5提取字符串中右数长度为i的字符串

string str = "GTAZB_JiangjBen_123";
string tSt;
int i=5;
tSt = str.Substring(str.Length - i); 
Console.WriteLine(tSt);
输出n_123;

6替换字符串中的特定字符串

string str = "GTAZB_JiangjBen_123";
string tSt;
tSt = str.Replace("123","321");
Console.WriteLine(tSt);
输出GTAZB_JiangjBen_321

7删除字符串中的特定字符串Jiangj  (JS方法  replace )

string str = "GTAZB_JiangjBen_123";
string tSt;
tSt = str.Replace("Jiangj","");
Console.WriteLine(tSt);
输出GTAZB_Ben_123

8删除指定位置(第i个)的指定长度（length）的字符串

string str = "GTAZB_JiangjBen_123";

int i=5,length=8;
str=str.remove(i,length);
console.writeline(str);

输出GTAZBen_123。

另附C# Split用法：

String.Split 方法有6个重载函数： 程序代码 1) public string[] Split(params char[] separator) 2) public string[] Split(char[] separator, int count)
3) public string[] Split(char[] separator, StringSplitOptions options)
4) public string[] Split(string[] separator, StringSplitOptions options)
5) public string[] Split(char[] separator, int count, StringSplitOptions options)
6) public string[] Split(string[] separator, int count, StringSplitOptions options)
下边我们通过一些实例来说明下怎么使用(以下string words = "1,2.3,,4";)：
1. public string[] Split(params char[] separator) 程序代码 string[] split = words.Split(new Char[] { "," });//返回:{"1","2.3","","4"}
string[] split = words.Split(new Char[] { ",", "." });//返回:{"1","2","3","","4"} 
2. public string[] Split(char[] separator, int count) 程序代码 string[] split = words.Split(new Char[] { ",", "." }, 2);//返回:{"1","2.3,,4"}
string[] split = words.Split(new Char[] { ",", "." }, 6);//返回:{"1","2","3","","4"} 
3. public string[] Split(char[] separator, StringSplitOptions options) 程序代码 string[] split = words.Split(new Char[] { ",", "." }, StringSplitOptions.RemoveEmptyEntries);//返回:{"1","2","3","4"} 不保留空元素
string[] split = words.Split(new Char[] { ",", "." }, StringSplitOptions.None);//返回:{"1","2","3","","4"} 保留空元素 
4. public string[] Split(string[] separator, StringSplitOptions options) 程序代码 string[] split = words.Split(new string[] { ",", "." }, StringSplitOptions.RemoveEmptyEntries);//返回:{"1","2","3","4"} 不保留空元素
string[] split = words.Split(new string[] { ",", "." }, StringSplitOptions.None);//返回:{"1","2","3","","4"} 保留空元素 
5. public string[] Split(char[] separator, int count, StringSplitOptions options) 程序代码 string[] split = words.Split(new Char[] { ",", "." }, 2, StringSplitOptions.RemoveEmptyEntries);//返回:{"1","2.3,,4"} 不保留空元素
string[] split = words.Split(new Char[] { ",", "." }, 6, StringSplitOptions.None);//返回:{"1","2","3","","4"} 保留空元素 
6. public string[] Split(string[] separator, int count, StringSplitOptions options) 程序代码 string[] split = words.Split(new string[] { ",", "." }, 2, StringSplitOptions.RemoveEmptyEntries);//返回:{"1","2.3,,4"} 不保留空元素
string[] split = words.Split(new string[] { ",", "." }, 6, StringSplitOptions.None);//返回:{"1","2","3","","4"} 保留空元素 需要注意的是没有重载函数public string[] Split(string[] separator)，所以我们不能像VB.NET那样使用words.Split(",")，而只能使用words.Split(","）