basic thread

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


#define NUM_THREADS  2
#define MAX_COUNT 100000000L

volatile long count = 0;

void *counter(void *threadid) {
    long tid, i, max = MAX_COUNT/NUM_THREADS;
    tid = (long)threadid;

    for (i=0; i < max; i++) {
        count++;
    }

    pthread_exit(NULL);
}

int main (int argc, char *argv[]) {
    pthread_t threads[NUM_THREADS];
    int rc;
    long t;

    for(t=0; t<NUM_THREADS; t++){
        rc = pthread_create(&threads[t], NULL, counter, (void *)t);
        if (rc){
            printf("ERROR; return code from pthread_create() is %d\n", rc);
            exit(-1);
        }
    }

    for(t=0; t<NUM_THREADS; t++){
        pthread_join(threads[t], NULL);
    }

    float error = (MAX_COUNT-count)/(float) MAX_COUNT *100;

    printf("Final result: %ld Expected: %ld Error: %3.2f%%\n", count, MAX_COUNT, error);

    puts("Bye from main");
    pthread_exit(NULL);
}