怎么用正则表达式提取字符串中有且仅有的连续的7位数字

Question

比如：
asdfafsa1234567
werfsfsd1234567dfg

Answer 1

^[\s\S]*\d{7}[\s\S]*$
^[\w\W]*\d{7}[\w\W]*$
^[\d\D]*\d{7}[\d\D]*$ 

Answer 2

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Text.RegularExpressions;namespace ConsoleApplication14
{
    class Program
    {
        static void Main(string[] args)
        {
            string str = "werfsfsd1234567dfg";
           str= Regex.Replace(str, @"[a-z]", "");
            Console.WriteLine(str);
            Console.ReadKey();
        }
    }
}

Answer 3

Regex objRegex = new Regex(@"(?<=\D|^)(?:(?:9(?=8|\D))?(?:8(?=7|\D))?(?:7(?=6|\D))?(?:6(?=5|\D))?(?:5(?=4|\D))?(?:4(?=3|\D))?(?:3(?=2|\D))?(?:2(?=1|\D))?(?:1(?=0|\D))?(?:0(?=\D|$))?)(?=\D|$)");            
MatchCollection objMatches = objRegex.Matches(str);

Answer 4

提取的话，这样就行了            Regex reg = new Regex(@"\d{7}");
            MatchCollection mc = reg.Matches(yourStr);
            foreach (Match m in mc)
            {
                richTextBox2.Text += m.Value + "\n";
            }