(?i)(?<=<td>)\d+(?=</td>)

------解决方案--------------------

建立一个1.txt，内容如下，结果自己试试
HTML code

<td>110</td>
<td>111</td>
<td>112</td>

------解决方案--------------------
探讨


C# code
            Regex reg = new Regex(@"(?i)(?<=<td>)\d+(?=</td>)");
            MatchCollection mc = reg.Matches("<td>111</td>");
            foreach (Match m in mc)
            {
             ……