mutext.c

/* Code sample */
#include <pthread.h>
#include <stdlib.h>
#include <unistd.h>
#include <stdio.h>
int myglobal;
pthread_mutex_t mymutex=PTHREAD_MUTEX_INITIALIZER;
void *thread_function(void *arg)
{
    int i,j;
    for ( i=0; i<10; i++ ) {
        pthread_mutex_lock(&mymutex);
        j=myglobal;
        j=j+1;
        printf(".");
        //fflush(stdout);
        //sleep(1);
        myglobal=j;
        pthread_mutex_unlock(&mymutex);
    }
    return NULL;
}
int main(void)
{
    pthread_t mythread;
    int i;
    if ( pthread_create( &mythread, NULL, thread_function, NULL) ) {
        printf("error creating thread.");
        abort();
    }
    for ( i=0; i<10; i++) {
        pthread_mutex_lock(&mymutex);
        myglobal=myglobal+1;
        pthread_mutex_unlock(&mymutex);
        printf("o");
        //fflush(stdout);
        //sleep(1);
    }
    if ( pthread_join ( mythread, NULL ) ) {
        printf("error joining thread.");
        abort();
    }
    printf("\nmyglobal equals %d\n",myglobal);
    exit(0);
}