IP判断C语言

解题思路:

注意事项:

参考代码:

#include<stdio.h>
int main()
{
char a[30];
int i=0,n=0;
while(gets(a))
{
    while(a[i]!='\0')
    {
        if(a[i]=='.'||(a[i]<='9'&&a[i]>='0'))   //只有正整数和.才进入判断
        {
            if(a[i]!='.')   
            {
                n=n*10+((int)a[i]-48);
            }
            else if((a[i-1]=='.'&&a[i]=='0')||a[0]=='0')    //1.0.0.1或者001,01
            {
                printf("N");
                break;
            }
            else
            {
                if(n>255)       //大于要求的数字
                {
                    printf("N");
                    break;
                }
                else
                {
                    n=0;
                }
            }
        }
        else    //非数字和.字符全部判断N
        {
            printf("N");
            break;
        }
        i++;
    }
    if(a[i]=='\0')
    {
        printf("Y");
    }
    printf("\n");
    i=0,n=0;
}
	return 0;
}