Pass by Value vs Pass by Reference

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Pass by Value vs Pass by Reference

When passing arguments to functions, C++ creates a copy by default (pass by value). Using the ampersand (&) in the parameter declaration creates a reference to the original variable (pass by reference). Pass by value protects the original from changes but uses more memory. Pass by reference allows modification but directly affects the caller's variable.

snippet.cpp

cpp

#include <iostream>
 
void byValue(int x) {
    x = x + 10;
}
 
void byReference(int& x) {
    x = x + 10;
}
 
int main() {
    int a = 5;
    int b = 5;
    
    byValue(a);
    std::cout << "byValue result: " << a << std::endl;
    
    byReference(b);
    std::cout << "byReference result: " << b << std::endl;
    
    return 0;
}

Breakdown

void byValue(int x)

Parameter x is a copy of the argument

void byReference(int& x)

Parameter x is a reference to original

a stays 5, b becomes 15

Demonstrates the key difference

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Pass by Value vs Pass by Reference

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