#include 
     
       int is_valid_ip(const char *ip) { int section = 0;  //每一节的十进制值     int dot = 0;       //几个点分隔符     int last = -1;     //每一节中上一个字符     while(*ip)     { if(*ip == '.')         {             dot++; if(dot > 3)             { return 0;             } if(section >= 0 && section <=255)             {                 section = 0;             }else{ return 0;             }         }else if(*ip >= '0' && *ip <= '9')         {             section = section * 10 + *ip - '0'; if(last == '0')             { return 0;             }         }else{ return 0;         }         last = *ip;         ip++;            } if(section >= 0 && section <=255)     { if(3 == dot)         {
           section = 0;         printf ("IP address success!\n");       //printf ("%d\n",dot);         return 0;       }     } return 1; } int main() {
       is_valid_ip("192.249.23.123"); }