Thread: Unexpected Error

A simple client with no errors in code gave me these errors? Any answers?

gcc client.c
Undefined first referenced
symbol in file
gethostbyname /var/tmp//ccJVrXcl.o
socket /var/tmp//ccJVrXcl.o
connect /var/tmp//ccJVrXcl.o
ld: fatal: Symbol referencing errors. No output written to a.out
collect2: ld returned 1 exit status

Code:

#include <stdio.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>
 
void error(char *msg)
{
    perror(msg);
    exit(0);
}
 
int main(int argc, char *argv[])
{
    int sockfd, portno, n;
    struct sockaddr_in serv_addr;
    struct hostent *server;
 
    char buffer[256];
    if (argc < 3) {
       fprintf(stderr,"usage %s hostname port\n", argv[0]);
       exit(0);
    }
    portno = atoi(argv[2]);
    sockfd = socket(AF_INET, SOCK_STREAM, 0);
    if (sockfd < 0)
        error("ERROR opening socket");
    server = gethostbyname(argv[1]);
    if (server == NULL) {
        fprintf(stderr,"ERROR, no such host\n");
        exit(0);
    }
 
    bzero((char *) &serv_addr, sizeof(serv_addr));
    serv_addr.sin_family = AF_INET;
    bcopy((char *)server->h_addr,
         (char *)&serv_addr.sin_addr.s_addr,
         server->h_length);
    serv_addr.sin_port = htons(portno);
 
    if (connect(sockfd,(struct sockaddr *) &serv_addr,sizeof(serv_addr))== -1){
        error("ERROR connecting");
        exit(0);
        }
    else
    printf("Please enter the message: \n");
    bzero(buffer,256);
    fgets(buffer,255,stdin);
    n = write(sockfd,buffer,strlen(buffer));
    if (n < 0)
         error("ERROR writing to socket");
    bzero(buffer,256);
    n = read(sockfd,buffer,255);
    if (n < 0)
         error("ERROR reading from socket");
    printf("%s\n",buffer);
    return 0;
}

What needs to be fixed in the includes? That is the initial reason why i posted this, i knew there was a problem with the include just by running:

gcc client.c -E

So any answers?

I'll assume you know what a man page is. Ok, so how about looking up each function to see what header it requires, eh?

man 3 exit


Quzah.

> gcc client.c

Code:

gcc client.c -lsocket

You need to specify one (or more) additional libraries to resolve the network API calls.
I'm not at a linux machine right now to remember whether that's the right name for the library.