C# Substring() 截取字符串的用法

语法：

public string Substring(int startIndex);
public string Substring(int startIndex, int length);

示例：

string id = "123456196108047890";
string birthdate = id.Substring(6);      //------------------196108047890
string brithdate = id.Substring(6,8); //--------------------19610804

string fileName = "Program.cs";
string strName = fileName.Substring(0,fileName.IndexOf('.'));  //------------Program
string strExten = fileName.Substring(fileName.IndexOf('.'));  //---------------.cs