The problem is to print odd and even number by using two threads respectively

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

#define MAX 10
pthread_cond_t cond_var =PTHREAD_COND_INITIALIZER;
pthread_mutex_t lock = PTHREAD_MUTEX_INITIALIZER;

int count =1;
void *odd_fun(void *arg)
{
  while(count<MAX)
  {
     pthread_mutex_lock(&lock);
     while( count % 2 ==0)
       pthread_cond_wait(&cond_var, &lock);
     printf("\n Odd thread creation %d\n", count);
     count++;
     pthread_cond_signal(&cond_var);
     pthread_mutex_unlock(&lock);
  }
}

void *even_fun(void *arg)
{
  while(count<MAX)
  {
     pthread_mutex_lock(&lock);
     while( count % 2 !=0)
       pthread_cond_wait(&cond_var, &lock);
     printf("\n Even thread printing: %d \n", count);
     count++;
     pthread_cond_signal(&cond_var);
     pthread_mutex_unlock(&lock);
  }

}

int main()
{
  pthread_t th_id[2];
  int res = pthread_create(&th_id[0], 0, odd_fun, 0);
  if(res)
  {
    printf("\n Thread creation failed: %s\n", strerror(res));
    exit(0);
  }
  res = pthread_create(&th_id[1], 0, even_fun, 0);
  if(res)
  {
    printf("\n Thread creation failed: %s\n", strerror(res));
    exit(0);
  }
  pthread_join(th_id[0], NULL);
  pthread_join(th_id[1], NULL);
  return 0;
}

Output:

 Odd thread creation 1                                                                                                                                                               
 
 Even thread printing: 2                                                                                                                                                             
 
 Odd thread creation 3                                                                                                                                                               
 
 Even thread printing: 4                                                                                                                                                             
 
 Odd thread creation 5                                                                                                                                                               
 
 Even thread printing: 6                                                                                                                                                             
 
 Odd thread creation 7                                                                                                                                                               
 
 Even thread printing: 8                                                                                                                                                             
 
 Odd thread creation 9                                                                                                                                                               
 
 Even thread printing: 10                                                                                                                                                            
 
 
...Program finished with exit code 0 
Press ENTER to exit console.  

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Relevant Post:

• Thread creates attributes
• Thread attributes(TCB)
• Characteristics of a Thread
• Odd-even problem

Categories: Operating system (OS)