找出字符串中找出连续最长的数字串代码实现及思路

#include <stdio.h>
#include <string.h>

#define DU 100

int continumax(char *outtstr,char *intstr);

int main()
{
     char instr[1024];
     char outstr[1024];
     int len = 0;
     printf("please input string!\n");
     scanf("%s",instr);
     printf("you input str is %s\n",instr);
     len = continumax(outstr,instr);
     printf("the result is %s\n the lenth is %d,\n",outstr,len);
     return 0;
}

int continumax(char *outtstr,char *intstr)
{
     int len = 0;
     int maxlen = 0;
     int i = 0;
    char *in = intstr;
    while(*in != '\0')
    {
          while(*in >= '0' && *in <= '9')
         {
                len++;
                in++;
          }
         if(len > maxlen)
         {
               maxlen = len;
              in = in - len;
              for(i = 0; i< maxlen;i++)
              {
                    outtstr[i] = *(in+i);
              }
             outtstr[maxlen] = '\0';
            in = in + len - 1;
            len = 0;//很重要
          }
          in++;
         len = 0;
      }
 return maxlen;
}