gethostbyname

#include <gmp.h>
#include <stdio.h>
#include <string.h>

int main2(int argc, const char *argv[])
{
    mpz_t z_i, z_s, z_o;        //定义多精度整数类型
    //用1初始化变量
    mpz_init_set_str(z_i, "1", 10);
    mpz_init_set_str(z_s, "1", 10);
    mpz_init_set_str(z_o, "1", 10);
    int i;

    //z_s=1*2*3*....*10000
    for (i = 0; i < 10000; i++)
    {
        mpz_mul(z_s, z_s, z_i); //z_s=z_s*z_i
        mpz_add(z_i, z_i, z_o); //z_i=z_i+z_o
    }
    gmp_printf("%Zd\n", z_s);      //输出和printf类似
    //释放空间
    mpz_clear(z_i);
    mpz_clear(z_s);
    mpz_clear(z_o);
    return 0;
}

#include "netdb.h"
#include <arpa/inet.h>
int main(int argc, const char *argv[])
{
    struct addrinfo hint = {0};
    hint.ai_flags = (AI_CANONNAME | AI_V4MAPPED | AI_ALL) & AI_MASK;
    hint.ai_socktype = SOCK_STREAM;
    hint.ai_family = AF_UNSPEC;
    struct addrinfo *res = NULL;
    if (getaddrinfo("baidu.com", NULL, &hint, &res))
        return 1;
    for (struct addrinfo *p = res; p; p = p->ai_next) {
        if (p->ai_family == AF_INET) {
            printf("IP addr: %s\n", inet_ntoa(((sockaddr_in*)p->ai_addr)->sin_addr));
        }
    }
    freeaddrinfo(res);
    struct hostent  * d = gethostbyname("baidu.com");
    if (d->h_addrtype == AF_INET /*AF_INET6*/ && d->h_length == 4 /*16*/)
        for(int i=0; d->h_addr_list[i]; i++){
            printf("IP addr %d: %s\n", i+1, inet_ntoa( *(struct in_addr*)d->h_addr_list[i] ) );
        }
    return 0;
}