inet_ntop()、inet_pton()、inet_addr()、inet_ntoa()函数之间的关系

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int inet_pton(int family, const char *strptr, void *addrptr)
{
    if (family == AF_INET) {
	    struct in_addr  in_val;
		if (inet_aton(strptr, &in_val)) {
		    memcpy(addrptr, &in_val, sizeof(in_val));
		    return (1);
		}
	}
	errno = EAFNOSUPPOPT;
	return (-1);
}

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const char *inet_ntop(int family, const void *addrptr, char *strptr, size_t len)
{
	const u_char *p = (const u_char*)addrptr;
	if (family == AF_INET) {
		char temp[INET_ADDRSTRLEN];
		snprintf(temp, sizeof(temp), "%d.%d.%d.%d", p[0], p[1], p[2], p[3]);
		if (strlen(temp) >= len) {
		    errno = ENOSPC;
		    rturn (NULL);
		}
		strcpy(strptr, temp);
		return (strptr);
	}
	errno = EAFNOSUPPOPT;
	return (NULL);
}

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in_addr_t inet_addr(const char *cp);

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char *inet_ntoa(struct in_addr in);

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char *add1,add2;
src.sin_addr.s_addr  =  inet_addr("192.168.1.123");
add1 =inet_ntoa(src.sin_addr);                  
src.sin_addr.s_addr = inet_addr("192.168.1.124");
add2 = inet_ntoa(src.sin_addr);
 
printf("a1:%sn",add1);
printf("a2:%sn",add2);

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用
inet_pton(AF_INET, cp, &src.sin_addr);
代替
src.sin_addr.s_addr = inet_addr(cp);

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用
char str[INET_ADDRATRLEN];
ptr = inet_ntop(AF_INET, &src.sin_addr, str, sizeof(str));
代替
ptr = inet_ntoa(src.sin_addr);