{"@context":"https://schema.org","@graph":[{"@type":"Article","headline":"Lesson 9: Parameter Passing – By Value and By Reference","description":"# Parameter Passing – By Value and By Reference\\n\\nUnderstanding how arguments are passed influences performance and semantics. By **value** copies the argument","articleBody":"# Parameter Passing – By Value and By Reference\\n\\nUnderstanding how arguments are passed influences performance and semantics. By **value** copies the argument, invoking copy constructors for class types. By **reference** (`T&`), the function works directly with the original object, avoiding a copy. Adding `const` to a reference (`const T&`) allows read‑only access without copying.\\n\\n---\\n\\n## Example: Demonstrating Copy vs Reference\\n```cpp\\nstruct Widget {\\n Widget() { std::cout << \\\"Widget constructed\\\\n\\\"; }\\n Widget(const Widget&) { std::cout << \\\"Widget copied\\\\n\\\"; }\\n ~Widget() { std::cout << \\\"Widget destroyed\\\\n\\\"; }\\n};\\n\\nvoid byValue(Widget w) {\\n std::cout << \\\"Inside byValue\\\\n\\\";\\n}\\n\\nvoid byRef(Widget& w) {\\n std::cout << \\\"Inside byRef\\\\n\\\";\\n}\\n\\nint main() {\\n Widget w;\\n byValue(w); // copy occurs\\n byRef(w); // no copy\\n return 0;\\n}\\n```\\n\\nOutput clarifies when the copy constructor runs. For large objects, prefer **pass‑by‑reference** to avoid expensive copies.\\n\\n> **Tip:** Use `std::move` to transfer resources when you intentionally want to move from a value.\\n\\n---\\n\\nNever return a reference to a local variable; it will dangle after the function exits.","author":{"@type":"Person","name":"Mohit"},"publisher":{"@type":"Organization","name":"BraveProgrammer","logo":{"@type":"ImageObject","url":"https://braveprogrammer.vercel.app/logo.png"}}},{"@type":"BreadcrumbList","itemListElement":[{"@type":"ListItem","position":1,"name":"Courses","item":"https://braveprogrammer.vercel.app/learning"},{"@type":"ListItem","position":2,"name":"C++ Course","item":"https://braveprogrammer.vercel.app/learning/cpp-basics"},{"@type":"ListItem","position":3,"name":"Lesson 9: Parameter Passing – By Value and By Reference","item":"https://braveprogrammer.vercel.app/learning/cpp-basics?lesson=8"}]}]}