C++ Call by Reference

In C++, call by reference passes the actual variable to the function using a reference. Changes made inside the function affect the original variable in the caller.

1. Call by Reference Syntax

The function receives a reference to the argument using the & symbol, allowing modifications to affect the original variable.

return_type function_name(data_type &parameter) {
    // function body
}

2. Call by Reference Example

This example demonstrates call by reference where changes inside the function modify the original variable.

#include <iostream>
using namespace std;

void increment(int &a) {
    a = a + 1;
    cout << "Inside function: " << a << endl;
}

int main() {
    int x = 5;
    increment(x);
    cout << "Outside function: " << x << endl;
    return 0;
}

3. Common Mistakes

Forgetting the & in the function parameter or expecting call by reference behavior in call by value are common mistakes. Always use & to modify the original variable.

Conclusion

C++ call by reference allows functions to modify the original variables. It is useful when you want functions to change data directly or avoid copying large objects.