hello_client.c

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <arpa/inet.h>
#include <sys/socket.h>

#define BUF_SIZE 1024
void error_handling(char *message);

int main(int argc, char *argv[]){

    int sock;
    int str_len, recv_len, recv_cnt;
    struct sockaddr_in serv_addr;
    char message[BUF_SIZE];

    sock = socket(PF_INET, SOCK_STREAM, 0);
    if(sock == -1)
        error_handling("socket() error");

    memset(&serv_addr, 0, sizeof(serv_addr));
    serv_addr.sin_family = AF_INET;
    serv_addr.sin_addr.s_addr = inet_addr(argv[1]);
    serv_addr.sin_port = htons(atoi(argv[2]));
    if(connect(sock, (struct sockaddr*)&serv_addr, sizeof(serv_addr)) == -1)
        error_handling("connect() error");
    else
        printf("Connected.......");

    while(1){
        fputs("Input message(Q to quit): ", stdout);
        fgets(message, BUF_SIZE, stdin);
        if(!strcmp(message, "q\n") || !strcmp(message, "Q\n"))
            break;
        str_len = write(sock, message, strlen(message));

        recv_len = 0;
        while(recv_len < str_len){
            recv_cnt = read(sock, &message, BUF_SIZE - 1);
            if(recv_cnt == -1)
                error_handling("read() error");
            recv_len += recv_cnt; 
        }
        message[recv_len] = 0;
        printf("Message from server: %s\n", message);
    }
    close(sock);

    return 0;
}

void error_handling(char *message){
    fputs(message, stderr);
    fputc('\n', stderr);
    exit(1);
}