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  1. #include <stdio.h>
  2.  
  3. void swapA (int a, int b) {
  4. 	printf("  start A: a: %d b: %d\n", a, b);
  5. 	int c = a;
  6. 	a = b;
  7. 	b = c;
  8. 	printf("    end A: a: %d b: %d\n", a, b);
  9. }
  10.  
  11. void swapB(int* a, int* b) {
  12. 	printf("  start B: a: %d b: %d\n", *a, *b);
  13.     int temp = *a;
  14.     *a = *b;
  15.     *b = temp;
  16. 	printf("    end B: a: %d b: %d\n", *a, *b);
  17. }
  18.  
  19. int main(void) {
  20. 	int foo = 42;
  21. 	int bar = 4;
  22.  
  23. 	swapA(foo, bar);
  24. 	printf("after A: foo: %d bar: %d\n", foo, bar);
  25. 	/* why didn't anything change? */
  26.  
  27. 	swapB(&foo, &bar);
  28. 	printf("after B: foo: %d bar: %d\n", foo, bar);
  29. 	/* what was different? */
  30. 	return 0;
  31. }
  32.  
Success #stdin #stdout 0s 2292KB
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stdin
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Standard input is empty
stdout
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  start A: a: 42 b: 4
    end A: a: 4 b: 42
after A: foo: 42 bar: 4
  start B: a: 42 b: 4
    end B: a: 4 b: 42
after B: foo: 4 bar: 42
https://ideone.com/cvI1Cg
language:
C (gcc 8.3)
created:
11 years ago
visibility:
public

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