Function Parameters

Parameters let you pass data into a function. They act like local variables initialized with the values you provide when calling the function.

void display(int count) {
  for (int i = 0; i < count; i++) {
    cout << i << " ";
  }
}

Pass by Value vs Reference

By default, C++ passes arguments by value — the function gets a copy. Changes inside the function don't affect the original.

void doubleVal(int x) {
  x = x * 2;
}

int main() {
  int num = 5;
  doubleVal(num);
  cout << num;
  return 0;
}

Use a reference parameter (&) to modify the original variable directly.

void doubleRef(int &x) {
  x = x * 2;
}

Use references when you want to avoid copying large data or need to modify the argument.