How do pass variable pass by reference in C?

user_12743948 0
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I want to display x,y,z value with pass by reference method how to do that?

  • What is the pass by value-result?

      void f1(int x, int y, int z){
      x = y + z;
      y = z + 1;
      printf("x: %d y:  %d z: %d",x,y,z);
  }

  int main(int argc, char *argv[]) {
      int r = 5;
      int t = 10;
      int k = 15;
      f1(r, t, t + k);
      printf(" r : %d t:  %d k : %d",r,t,k);
  }

Any help is appreciated.

pass-by-reference arguments function c variables
1 Answers

It's just a case of using indirection, which in C means pointers:

// Declare any arguments that are mutated as pointers
void f1(int* x, int* y, int z) {
  *x = *y + z;
  *y = z + 1;
  printf("x: %d y:  %d z: %d", *x, *y, z);
}

int main(int argc, char *argv[]) {
  int r = 5;
  int t = 10;
  int k = 15;
  f1(&r, &t, t + k);
  printf(" r : %d t:  %d k : %d",r,t,k);
}

Note that in order to use pointers you must have something to point to. t + k is not of those things. Arguably z is not mutated as an argument, so it could be a plain int.

As far as order of operations goes, t + k is computed and assigned as the argument before mutations occur.

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