int is_valid_ip(const char *ip)

{

int section = 0;? //每一節的十進制值

int dot = 0;?????? //幾個點分隔符

int last = -1;???? //每一節中上一個字符

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){

section = 0;

}

return 1;

}