Error when process run an instance of xterm with fork

Question

I am given the task of forking n processes.

For each process, it must start an instance of /bin/xterm

I am done with the part of generating n processes and opening the xterm instance.

I got this output when I tried running the program. (Error in bold)

Number of process to open is 1.

Child (1): 3457

/bin/xterm: Xt error: Can't open display:

/bin/xterm: DISPLAY is not set

My code is below.

I tried googleing for the error but I have no luck so far.

Any solutions?

#include<stdio.h>
#include<stdlib.h>

int main(int argc, char *argv[])
{
    int num = atoi(argv[1]);
    printf("Number of process to open is %d.\n", num);
    int pid;
    int i;

    for(i = 0; i < num; i++)
    {
        pid = fork();
        if(pid < 0) {
            printf("Error");
            exit(1);
        } else if (pid == 0) {
            printf("Child (%d): %d\n", i + 1, getpid());
            char * const argv[] = {"/bin/xterm", NULL};
            char * const envp[] = {NULL};
            int rc = execve ("/bin/xterm", argv, envp);
            exit(0); 
        } else  {
            wait(NULL);
        }
    }
    return 0;
}

Answer 1

This little changed code works perfectly fine on my system:

    #include<stdio.h>
#include<stdlib.h>
#include<unistd.h>

int main(int argc, char *argv[])
{
    int num = atoi(argv[1]);
    printf("Number of process to open is %d.\n", num);
    int pid;
    int i;

    for(i = 0; i < num; i++)
    {
        pid = fork();
        if(pid < 0) {
            printf("Error");
            exit(1);
        } else if (pid == 0) {
      //printf("Child (%d): %d\n", i + 1, getpid());
            //char * const argv[] = {"/bin/xterm", NULL};
            //char * const envp[] = {NULL};
            execl("/usr/bin/xterm", "/usr/bin/xterm", NULL);
            //exit(0); 
        }else  {
            wait(NULL);
        }
    }
    return 0;
}