C++ Academy · Lesson

Pass-by-Value vs Pass-by-Reference

Compare semantic and performance differences between passing by value and by reference.

Pass-by-Value Recap

When you pass an argument by value, the function gets a copy. Changes inside the function do not affect the caller.

void increment(int x) {
    x++;          // modifies the copy
}

int n = 5;
increment(n);
std::cout << n;   // still 5

Pass by reference using & in the parameter list. The function works directly on the caller s variable.

void increment(int& x) {
    x++;
}

int n = 5;
increment(n);
std::cout << n;   // now 6