pthread-example.c

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

/* this function is run by the second thread */
void *inc_x(void *x_void_ptr)
{

/* increment x to 100 */
int *x_ptr = (int *)x_void_ptr;
while(++(*x_ptr) < 100);

printf("x increment finished\n");

/* the function must return something - NULL will do */
return NULL;

}

int main()
{

int x = 0, y = 0;

/* show the initial values of x and y */
printf("x: %d, y: %d\n", x, y);

/* this variable is our reference to the second thread */
pthread_t inc_x_thread;

/* create a second thread which executes inc_x(&x) */
if(pthread_create(&inc_x_thread, NULL, inc_x, &x)) {

fprintf(stderr, "Error creating thread\n");
return 1;

}
/* increment y to 100 in the first thread */
while(++y < 100);

printf("y increment finished\n");

/* wait for the second thread to finish */
if(pthread_join(inc_x_thread, NULL)) {

fprintf(stderr, "Error joining thread\n");
return 2;

}

/* show the results - x is now 100 thanks to the second thread */
printf("x: %d, y: %d\n", x, y);

return 0;

}

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

/* this function is run by the second thread */
void *inc_x(void *x_void_ptr)
{

    /* increment x to 100 */
    int *x_ptr = (int *)x_void_ptr;
    while (++(*x_ptr) < 100)
        ;

    printf("x increment finished\n");

    /* the function must return something - NULL will do */
    return NULL;
}

int main()
{

    int x = 0, y = 0;

    /* show the initial values of x and y */
    printf("x: %d, y: %d\n", x, y);

    /* this variable is our reference to the second thread */
    pthread_t inc_x_thread;

    /* create a second thread which executes inc_x(&x) */
    if (pthread_create(&inc_x_thread, NULL, inc_x, &x))
    {
        fprintf(stderr, "Error creating thread\n");
        return 1;
    }
    /* increment y to 100 in the first thread */
    while (++y < 100)
        ;

    printf("y increment finished\n");

    /* wait for the second thread to finish */
    if (pthread_join(inc_x_thread, NULL))
    {

        fprintf(stderr, "Error joining thread\n");
        return 2;
    }

    /* show the results - x is now 100 thanks to the second thread */
    printf("x: %d, y: %d\n", x, y);

    return 0;
}