Returning int and string from a thread

22042017.c

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

void *returnintanswer( void *ptr );
void *returnstringanswer( void *ptr );

int main()
{
    // char buffer[1024];
    // int rcount = read(0, buffer, sizeof(buffer));

    int a[] = {2, 4};

    pthread_t thread1, thread2;
    const char *message1 = "Thread 1";
    const char *message2 = "Thread 2";
    int  iret1, iret2;

    /* Create independent threads each of which will execute function */

    iret1 = pthread_create( &thread1, NULL, returnintanswer, (void*) a);
    
    if(iret1)
    {
        fprintf(stderr,"Error - pthread_create() return code: %d\n",iret1);
        exit(EXIT_FAILURE);
    }

    iret2 = pthread_create( &thread2, NULL, returnstringanswer, (void*) a);
    if(iret2)
    {
        fprintf(stderr,"Error - pthread_create() return code: %d\n",iret2);
        exit(EXIT_FAILURE);
    }

    printf("pthread_create() for thread 1 returns: %d\n",iret1);
    printf("pthread_create() for thread 2 returns: %d\n",iret2);

    /* Wait till threads are complete before main continues. Unless we  */
    /* wait we run the risk of executing an exit which will terminate   */
    /* the process and all threads before the threads have completed.   */
    int answer = 0;
    pthread_join( thread1, (void **)&answer);

    // char an[4]  doesnt work 
    char *an = (char *) malloc(4);
    pthread_join( thread2, (void **)&an); 

    printf("ans int: %d\n", answer);
    printf("ans string: %s\n", an);

exit(EXIT_SUCCESS);
}

void *returnintanswer( void *ptr )
{
    int answer = 0;
    int *val = (int *)ptr;

    answer = val[0] + val[1];

    pthread_exit((void **)answer);
}

void *returnstringanswer( void *ptr )
{
    char *answer;

    /* Initial memory allocation */
    answer = (char *) malloc(4);

    // char answer[4] ===> array type declarations dont work
    int *val = (int *)ptr;
    int ans = 0;

    
    ans = val[0] + val[1];

    int pcount = sprintf(answer, "%d\n", ans);

    // printf("%d", pcount);
    pthread_exit((void **)answer);
}