c中怎么实现查看两个字符串的匹配情况，返回能够匹配的字符的个数

排序后再比较计数。
用C#演示一下，C的处理方式类似。

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Xml.Linq;

namespace ConsoleApplication1
{
    class Program
    {
        static void BubbleSort(char[] a)
        { 
            ...
        }

        static int CalcMatchCount(string s1, string s2)
        {
            char[] a1 = s1.ToCharArray();
            char[] a2 = s2.ToCharArray();
            BubbleSort(a1);
            BubbleSort(a2);
            // DEBUG
            Console.WriteLine(new string(a1));
            Console.WriteLine(new string(a2));

            int c = 0;
            for (int i1 = 0, i2 = 0; (i1 < a1.Length) && (i2 < a2.Length); )
            {
                switch (Math.Sign( a1[i1].CompareTo(a2[i2])))
                {
                    case -1:
                        i1++;
                        break;
                    case 0:
                        c++;
                        i1++;
                        i2++;
                        break;
                    case 1:
                        i2++;
                        break;
                }

            }
            return c;
        }

        static void Main(string[] args)
        {
            string s1 = "w_angqmab";
            string s2 = "w+bangemx";
            Console.WriteLine(CalcMatchCount(s1, s2));
            Console.ReadLine();
        }
    }
}

结果

_aabgmnqw
+abegmnwx
6