题解 | #验证IP地址#

/**
 * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
 *
 * 验证IP地址
 * @param IP string字符串 一个IP地址字符串
 * @return string字符串
 */

#include <ctype.h>
#define isValid(ip) (ip >= 0 && ip <= 255)

char* solve(char* IP ) {
    // write code here
    int i = 0;
    int ipv4 = 0;
    int ipv6 = 0;
    char temp[5];
    int idx = 0;
    while(IP[i] != '.' && IP[i] != ':' && IP[i] != '\0') {
        temp[idx] = IP[i];
        if(isalpha(IP[i])) ipv4 = -1;
        idx++;
        i++;
    }
    temp[idx] = '\0';
    printf("temp is %s\n", temp);
    if(IP[i] == '.') {
        if(temp[0] == '0' && temp[1]) return "Neither";
        int ip = atoi(temp);
        if(isValid(ip)) {
            ipv4++;
            i++;
            for(int j = ipv4; j < 4; j++) {
                idx = 0;
                while(IP[i] != '.' && IP[i] != '\0') {
                    if(!isdigit(IP[i])) return "Neither";
                    temp[idx] = IP[i];
                    idx++;
                    i++;
                }
                temp[idx] = '\0';
                printf("temp is %s\n", temp);
                if(temp[0] == '0' && temp[1]) return "Neither";
                if(idx == 0) return "Neither";
                ip = atoi(temp);
                printf("atoi : %d\n", ip);
                if(isValid(ip)) {
                    ipv4++;
                    i++;
                } else {
                    return "Neither";
                }
            }
        }
    } else if(IP[i] == ':') {
        i = 0;
        for(int j = 0; j < 8; j++) {
            idx = 0;
            while(IP[i] != ':' && IP[i] != '\0') {
                if(idx <= 3 && isdigit(IP[i]) || (IP[i] >= 'A' && IP[i] <= 'F' || (IP[i] >= 'a' && IP[i] <= 'f'))) {
                    temp[idx] = IP[i];
                    idx++;
                    i++;
                } else {
                    return "Neither";
                }
            }
            temp[idx] = '\0';
            if(idx == 0) return "Neither";
            printf("%s\n", temp);
            i++;
            ipv6++;
        }
    } else {
        return "Neither";
    }

    if(ipv4 == 4 && IP[i - 1] == '\0') return "IPv4";
    else if(ipv6 == 8 && IP[i - 1] == '\0') return "IPv6";
    return "Neither";
}