Why am I not getting different thread ids when I uses " #pragma omp parallel num\_threads(4)". All the thread ids are 0 in this case. 
But when I comment the line and use default number of threads, I got different thread ids.
Note:- variable I used variable tid to get thread id.

```
#include <omp.h>
#include <stdio.h>
#include <stdlib.h>

int main (int argc, char *argv[]) 
{
int nthreads, tid;
int x = 0;

#pragma omp parallel num_threads(4)
#pragma omp parallel private(nthreads, tid)
  {
  /* Obtain thread number */
 tid = omp_get_thread_num();
  printf("Hello World from thread = %d\n", tid);

  // /* Only master thread does this */
   if (tid == 0) 
     {
     nthreads = omp_get_num_threads();
     printf("Number of threads = %d\n", nthreads);
     }

  }

}

```

Output of above code:-

```
Hello World from thread = 0
Hello World from thread = 0
Number of threads = 1
Hello World from thread = 0
Number of threads = 1
Hello World from thread = 0
Number of threads = 1
Number of threads = 1

```

Output when I comment the line mentioned above:-

```
Hello World from thread = 3
Hello World from thread = 0
Number of threads = 4
Hello World from thread = 1
Hello World from thread = 2

```