Multiple forks

This is the code for generate a dynamic number of process (with the system call fork()). The father wait that all the child processes finish.

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

    if (argc != 2){
        puts("usage prog number_of_process");
        exit(EXIT_FAILURE);
    }

    int num = atoi(argv[1]);
    int i;
    int * pids = malloc(sizeof(int)*num);

    for(i = 0; i < num; i++){

        pids[i] = fork();

        if(pids[i] == 0){
            //This is the code of the child process
            printf("begin %d\n" , i);
            sleep(10); //simulation of work
            printf("finish %d\n", i);
            exit(EXIT_SUCCESS);
        }
    }

    //Waiting the finish of all child processes
    while(wait(NULL)){
        if(errno == ECHILD)
            break;
    }
}