详细题目描述如下图:
代码:
#include <stdio.h>
#include <string.h>
#include <ctype.h>
char* validIPAddress(char* IP)
{
int flag = 0;
int len = 0;
int num = 0;
int Count = 0;
int first = 0;
int i = 0,j=0;
if(IP == NULL)
{
return "Neither";
}
len = strlen(IP);
if (strchr(IP,'.') != NULL) // 含 .的情况,判断是否是IPv4
{
for(i = 0;i <= len-1; i++)
{
if(IP[i] >= '0' && IP[i] <= '9')
{
num = num * 10 + IP[i] - '0';
}
else if(IP[i] == '.')
{
if((i == 0)||(i == len-1))
{
break;
}
if(IP[i-1] < '0' || IP[i-1] > '9')
{
break;
}
if(IP[i] == '.')
{
Count++;
if(Count > 3)
{
break;
}
}
if(num > 255)
{
break;
}
if(num != 0 && IP[first] == '0')
{
break;
}
first = i+1;
num = 0;
}
else
{
break;
}
}
if(Count == 3)
{
flag = 1;
}
}
else if (strchr(IP,':') != NULL) // 含 :的情况,判断是否是IPv6
{
for(i = 0;i <= len-1; i++)
{
if((IP[i] >= '0' && IP[i] <= '9')||(tolower(IP[i]) >= 'a' && tolower(IP[i]) <= 'f'))
{
j++;
if (j > 4)
{
break;
}
}
else if(IP[i] == ':')
{
if((i == 0)||(i == len-1))
{
break;
}
if (j == 0)
{
break;
}
Count++;
if(Count > 7)
{
break;
}
j = 0;
}
else
{
break;
}
}
if((Count == 7)&&(j <= 4))
{
flag = 2;
}
}
if (flag == 1)
{
return "IPv4";
}
else if (flag == 2)
{
return "IPv6";
}
else
{
return "Neither";
}
}
int main(void)
{
printf("%s\n",validIPAddress("172.16.254.1"));
printf("%s\n",validIPAddress("172.016.254.1"));
printf("%s\n",validIPAddress("172.16.254."));
printf("%s\n",validIPAddress("172..254.1"));
printf("%s\n",validIPAddress("256.256.256.256"));
printf("%s\n",validIPAddress("2001:0db8:95a3:0:0:8A2E:0370:7334"));
printf("%s\n",validIPAddress("02001:0db8:95a3:0:0:8A2E:0370:7334"));
printf("%s\n",validIPAddress("2001:0db8:95a3::0:8A2E:0370:7334"));
printf("%s\n",validIPAddress("2001:0db8:95a3:0:0:8A2E:0370:"));
printf("%s\n",validIPAddress("2001:0db8:95a3:0:0:8A2E:0370:02345"));
return 0;
}
测试结果:
IPv4
Neither
Neither
Neither
Neither
IPv6
Neither
Neither
Neither
Neither