Functions

Comments

• pseudocoder

  April 2015

  Pass by value is copy of the variable where any changes made to it apply only within the scope of that function.

  Pass by reference is the address of the variable, which can be modified within a function and apply throughout the life of the variable

  void passByValue(int n) // copy of a variable
  { 
      n = 10;  // change is local to this function only
  }            
  
  void passByReference(int *n)  // address of a variable
  {
      *n = 10; // changes variable through its address
               // n is a pointer to an address
               // *n derefences the pointer to change the
               // value at that address 
  }
  
  int main(void)
  {
      int x = 0;
  
      passByValue(x); // pass a copy of x to the function
      printf("passByValue: %d\n", x);       // x should still be 0
  
      passByReference(&x); // pass the address of x to the function
      printf("passByReference: %d\n", x);   // x should now be 10
  
      ...
  }

  HTH