c语言实现IP地址输入的检查

#include 
#include 
#include 

char IPcheck(char * startbuff)
{
	char * pbuffer = NULL;
	char * ptemp = NULL;
	char ret = 0;
	char i = 0, j = 0;
	char temp[8] = {0};

	ptemp = startbuff;
	for (i = 0; i < 4; i++)
	{
		pbuffer = strstr(ptemp,".");
		/* find "." fail */
		if( (pbuffer == NULL)&&(i != 3) )
		{
			ret = 1;
			goto out;
		}

		/* end of string*/
		if (i == 3 && pbuffer == NULL)
		{
			pbuffer = startbuff + strlen(startbuff);
		}
		/* between “.” is vaid */
		if (pbuffer == ptemp)
		{
			ret = 1;
			printf("equ\r\n");
			goto out;
		}
		/* slect the between "." string value */
		for (j = 0; j < pbuffer - ptemp; j++)
		{
			if (ptemp < pbuffer)
			{
				temp[j] = ptemp[j];
			}
			else
			{
				break;
			}
		}
		/* turn to int value form string */
		if( (atoi(temp) > 0xff)||(atoi(temp) == 0x00) )
		{
			printf("no ok, %d\r\n", atoi(temp));
			ret = 1;
			goto out;
		}
		else
		{
			printf("ok, %d\r\n", atoi(temp));

		}
		ptemp = pbuffer + 1;
		for (j = 0; j < 8; j++)
		{
			temp[j] = 0;
		}
	}


out:
	if (ret == 1)
	{
		printf("fail i = %d\r\n", i);
	}
	return ret;
}

int main(void)
{
	char ret = 0;
	char ip[] = "2.1.12.4";
	ret = IPcheck(ip);
	if (ret != 0)
	{
		/* error */
	}
	system("pause");
	return 0;
}