How can I resolve this error: segmentation fault? - c

Question

#include <sys/socket.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <netdb.h>
#include <stdio.h>
#include <arpa/inet.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
int main(int argc, char *argv[]){
int sockfd;
struct sockaddr_in serv_addr;
struct hostent *hp;
char buff[100];
//Create socket
sockfd = socket(AF_INET, SOCK_STREAM, 0);
if(sockfd < 0){
perror("Failed to create socket!");
exit(1);
}
serv_addr.sin_family = AF_INET;
hp = gethostbyname(argv[1]); *
I think the error might be on the above line but I don't know how to solve
this.
When I compile, build and run this code in Geany, Linux, I get a segmentation fault error message. Why is it so and how can I resolve it?

Answer 1

You need to check that argc[1] exists.
A simple :
if (!argv[1])
return (-1);
will probably do the trick.
Tip : Valgrind and GDB are two very powerful tools to find where your errors come from and solve them.
It takes a bit of time to get used to reading the logs from these but I guarantee that once you'll be used to it, not only will most of your timeouts and SegFaults be much easier to solve but you'll also be able to optimise the memory consumption of your programs as it tracks memory leaks, allocs and free(s).

Answer 2

If you use linux,
ulimit -a
ulimit -c ulimited // set core file size limitless
then run executable again.A core file will be created.This is snapshot of last stack before segmentation fault.
gdb [executable] core
Now You can see where segmentation fault raises.

Answer 3

I think your problem lies here
hp = gethostbyname(argv[1]);
you should have sent something on console as parameter otherwise this space (argv[1]) is invalid thus segmentation fault occurs.
In your case parameter should be name of computer you are trying to connect to. For example:
./program hosToConnectTo
should do the trick.