我有以下代码，它使用正则表达式查找给定字符串中的所有网址：
Dim regex As New Regex("(http(s)?:\/\/.)?(www\.)?[-a-zA-Z0-9@:%._\+~#=]{2,256}\.[a-z]{2,6}\b([-a-zA-Z0-9@:%_\+.~#?&//=]*)", RegexOptions.IgnoreCase)
现在，我想用超链接替换所有匹配项：
For Each match As Match In mactches
strtemp &= strtemp.Replace(match, "<a target='_blank' href='mailto:" & match & "'>" & match & "</a>")
Next
正则表达式工作正常但更换时存在问题。假设我的输入字符串如下：
www.google.com is as same as google.com and also http://google.com
代码首先将www.google.com替换为<a>，然后，当第二个匹配（google.com）出现时，它将再次替换前一个匹配。那么，实现这一目标的方法是什么？
答案 0 :(得分：4)
如果您使用using System;
using System.Collections.Generic;
using AppName.Math;
using Xamarin.Forms;
using Plugin.Messaging;
using AppName.Flashcards;
using AppName.Science;
namespace AppName
{
public partial class AppNameHome : ContentPage
{
public SchoolToolsHome()
{
InitializeComponent();
var name = new List<Tools>
{
new Tools("Internet", "web.png"),
new Tools("E-Mail", "email.png"),
new Tools("Math", "math.png"),
new Tools("Science", "sci.png"),
new Tools("Handwriting","handwriteing.png"),
new Tools("FlashCards", "flashcard.png"),
};
listView.ItemsSource = name;
}
void OnItemSelected(object sender, SelectedItemChangedEventArgs e)
{
var tools = e.SelectedItem as Tools;
if (tools == null)
{
return;
}
ContentPage page = null;
switch (tools.Name)
{
case "Math":
page = new MathPage();
break;
case "Internet":
Device.OpenUri(new Uri("http://www.google.com"));
page = new AppNameHome();
break;
case "E-Mail":
Device.OpenUri(new Uri("mailto:"));
page = new AppNameHome();
break;
case "FlashCards":
page = new FlashCardHome();
break;
case "Science":
page = new ScienceHome();
break;
default:
page = new AppNameHome();
break;
}
((ListView)sender).SelectedItem = null;
page.BindingContext = tools;
Navigation.PushAsync(page);
}
public void OpenBooks(object sender, EventArgs e)
{
switch (Device.OS)
{
case TargetPlatform.iOS:
Device.OpenUri(new Uri("itms-books:"));
break;
case TargetPlatform.Android:
DependencyService.Get<OpenBookInterface>().openBooks();
break;
}
}
public void gotosettings(object sender, EventArgs e)
{
Navigation.PushAsync(new SettingsPage());
}
}
}
，它将正常工作，因为它会在找到它们时替换每个匹配项，而不是同时替换所有其他匹配项：
Regex.Replace但是，如果您每次调用它时只是重新创建Dim pattern As String = "(http(s)?:\/\/.)?(www\.)?[-a-zA-Z0-9@:%._\+~#=]{2,256}\.[a-z]{2,6}\b([-a-zA-Z0-9@:%_\+.~#?&//=]*)"
Dim regex As New Regex(pattern, RegexOptions.IgnoreCase)
Dim input As String = "www.google.com is as same as google.com and also http://google.com"
Dim output As String = regex.Replace(input, "<a target='_blank' href='mailto:$&'>$&</a>")
对象，则可以改为使用静态Regex方法。
Regex.Replace是一个特殊的替换表达式，它指示$&方法在替换字符串中的该点插入整个匹配。有关其他替换表达式，请参阅MSDN quick reference页面上的部分。