#include <stdio.h>

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");
}