在实际开发中经常要用到string的各种截取等操作，在这里总结自己认为经常出现的.NET 字符串的截取、移除、替换、插入操作，方面以后查阅。
前台代码：
<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="string.aspx.cs" Inherits="demo._string" %> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" > <head runat="server"> <title>无标题页</title> </head> <body> <form id="form1" runat="server"> <div> <asp:TextBox ID="TextBox1" runat="server"></asp:TextBox> <asp:Button ID="Button1" runat="server" onclick="Button1_Click" Text="Button" /> </div> </form> </body> </html>
后台代码：
using System; using System.Collections; using System.Configuration; using System.Data; using System.Linq; using System.Web; using System.Web.Security; using System.Web.UI; using System.Web.UI.HtmlControls; using System.Web.UI.WebControls; using System.Web.UI.WebControls.WebParts; using System.Xml.Linq; namespace demo { public partial class _string : System.Web.UI.Page { protected void Page_Load(object sender, EventArgs e) { if (IsPostBack == false) { string a = "123a4a4b5b6"; TextBox1.Text = a; } } protected void Button1_Click(object sender, EventArgs e) { string b = TextBox1.Text; ////截取前两位 123a4a4b5b6 12 //string c = b.Substring(0, 2); //TextBox1.Text = c; ////截取后两位 123a4a4b5b6 56 //string c = b.Substring(b.Length - 2, 2); //TextBox1.Text = c; ////截取最后一个字符“a”后面的3位字符 123a4a4b5b6 a4b //string c = b.Substring(b.LastIndexOf("a"), 3); //TextBox1.Text = c; ////截取最后一个字符“a”后面所有的字符 123a4a4b5b6 a4b5b6 //string c = b.Substring(b.LastIndexOf("a")); //TextBox1.Text = c; ////截取最后一个字符“a”前面所有的字符 123a4a4b5b6 123a4 //string c = b.Remove(b.LastIndexOf("a")); //TextBox1.Text = c; //// 截取最后一个字符“a”前面所有的字符 123a4a4b5b6 123a4 //string c = b.Substring(0, b.LastIndexOf("a")); //TextBox1.Text = c; ////截取最后一个字符“a”前面的3位字符 123a4a4b5b6 123a4 3a4 //string c = b.Remove(b.LastIndexOf("a")); //string d = c.Remove(0, c.Length - 3); //TextBox1.Text = d; //// 截取最后一个字符“a”前面的3位字符 123a4a4b5b6 3a4 //string c = b.Substring(2,b.LastIndexOf("a")-2); //TextBox1.Text = c; ////截取第一个字符"b"前面所有的字符 123a4a4b5b6 123a4a4 //int index = b.IndexOf("b"); //string c = b.Substring(0,index); //TextBox1.Text = c; ////截取第一个字符"b"前面的3位字符 123a4a4b5b6 4a4 //string c = b.Substring(0, b.IndexOf("b")); //string d = c.Substring(c.Length - 3, 3); //TextBox1.Text = d; ////截取第一个字符"b"前面的3位字符 123a4a4b5b6 4a4 //string c = b.Substring(b.IndexOf("b")-3,3); //TextBox1.Text = c; ////截取第一个字符"b"后面所有的字符 123a4a4b5b6 b5b6 //int index = b.IndexOf("b"); //string c = b.Substring(index,b.Length-index); //TextBox1.Text = c; //////截取第一个字符"b"后面3位字符 123a4a4b5b6 b5b //int index = b.IndexOf("b"); //string c = b.Substring(index, 3); //TextBox1.Text = c; ////移除从第三位开始的3个字符 123a4a4b5b6 1234b5b6 //string c = b.Remove(3, 3); //TextBox1.Text = c; ////移除字符串中的所有字符b; 123a4a4b5b6 123a4a456 //string c = b.Replace("b", ""); //TextBox1.Text = c; ////移除字符串中的第一个字符a 123a4a4b5b6 1234a4b5b6 //int index = b.IndexOf("a",1); //b=b.Remove(index, 1); //TextBox1.Text = b; ////移除字符串中的第一个字符a的后两位 123a4a4b5b6 123a4b5b6 //int index = b.IndexOf("a", 1); //b = b.Remove(index, 2); //TextBox1.Text = b; ////移除字符串中的第二个字符a 123a4a4b5b6 123a4b5b6 //int index = b.IndexOf("a", 2); //b = b.Remove(index, 2); //TextBox1.Text = b; ////移除字符串中的第二个字符a的后两位 123a4a4b5b6 123a4b5b6 //int index = b.IndexOf("a", 1); //b = b.Remove(index, 2); //TextBox1.Text = b; ////移除字符串中最后一个字符b 123a4a4b5b6 123a4a4b56 //int index = b.LastIndexOf("b"); //string c = b.Remove(b.LastIndexOf("b"),1); //TextBox1.Text = c; ////移除字符串中最后一个字符b的后两位 123a4a4b5b6 123a4a4b5 //int index = b.LastIndexOf("b"); //string c = b.Remove(b.LastIndexOf("b"), 2); //TextBox1.Text = c; ////替换字符串中所有的字符“a”,为“b”; 123a4a4b5b6 123b4b4b5b6 //string c = b.Replace("a", "b"); //TextBox1.Text = c; ////替换字符中的第一个字符a为R 123a4a4b5b6 123R4a4b5b6 //int index = b.IndexOf("a"); //string c= b.Remove(index, 1).Insert(index, "R"); //TextBox1.Text = c; ////替换字符中的最后一个字符a为R 123a4a4b5b6 123a4R4b5b6 //int index = b.LastIndexOf("a"); //string c = b.Remove(index, 1).Insert(index, "R"); //TextBox1.Text = c; ////插入I在第一个a之前 123a4a4b5b6 123Ia4a4b5b6 //int index = b.IndexOf("a"); //string c = b.Insert(index, "I"); //TextBox1.Text = c; ////插入I在第一个a之后 123a4a4b5b6 123aI4a4b5b6 //int index = b.IndexOf("a"); //string c = b.Insert(index+1, "I"); //TextBox1.Text = c; ////插入I在最后一个a之前 123a4a4b5b6 123a4Ia4b5b6 //int index = b.LastIndexOf("a"); //string c = b.Insert(index, "I"); //TextBox1.Text = c; //插入I在最后一个a之后 123a4a4b5b6 123a4aI4b5b6 int index = b.LastIndexOf("a"); string c = b.Insert(index + 1, "I"); TextBox1.Text = c; } } }