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  1. #include <stdio.h>
  2. #include <omp.h>
  3.  
  4. int x = 5;
  5.  
  6. int main() {
  7.   printf("=== BEFORE PARALLEL REGION ===");
  8.   printf("\nGlobal x address: %p", (void*)&x);
  9.   printf("\nGlobal x value: %d\n", x);
  10.  
  11.   #pragma omp parallel sections private(x)
  12.   {
  13.     #pragma omp section
  14.     {
  15.       printf("\n  x address: %p", (void*)&x);
  16.       printf("\n  x value BEFORE init: %d (garbage)", x);
  17.  
  18.       x = 5;
  19.       printf("\n  x value AFTER init: %d", x);
  20.  
  21.       x++;
  22.       printf("\n  x value AFTER increment: %d", x);
  23.       printf("\n  x=%d from first (private)", x);
  24.     }
  25.  
  26.     #pragma omp section
  27.     {
  28.       printf("\n  x address: %p", (void*)&x);
  29.       printf("\n  x value BEFORE init: %d (garbage)", x);
  30.  
  31.       x = 5;
  32.       printf("\n  x value AFTER init: %d", x);
  33.  
  34.       x--;
  35.       printf("\n  x value AFTER decrement: %d", x);
  36.       printf("\n  x=%d from second (private)", x);
  37.     }
  38.   }
  39.  
  40.   printf("\n\n=== AFTER PARALLEL REGION ===");
  41.   printf("\nGlobal x address: %p", (void*)&x);
  42.   printf("\nGlobal x value: %d", x);
  43.   printf("\n\n");
  44.  
  45.   return 0;
  46. }
Success #stdin #stdout 0s 5288KB
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stdin
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Standard input is empty
stdout
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=== BEFORE PARALLEL REGION ===
Global x address: 0x55f9808f1010
Global x value: 5

  x address: 0x55f9808f1010
  x value BEFORE init: 5 (garbage)
  x value AFTER init: 5
  x value AFTER increment: 6
  x=6 from first (private)
  x address: 0x55f9808f1010
  x value BEFORE init: 6 (garbage)
  x value AFTER init: 5
  x value AFTER decrement: 4
  x=4 from second (private)

=== AFTER PARALLEL REGION ===
Global x address: 0x55f9808f1010
Global x value: 4
https://ideone.com/EI763E
language:
C (gcc 8.3)
created:
7 hours ago
visibility:
public

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