Try It Yourself - SyntaxStudy Editor

HTML / CSS / JS

#include <iostream>
#include <string>

// Pass by value: a copy is made
void byValue(std::string s) {
    s += " (modified)";
    std::cout << "inside byValue: " << s << "
";
}

// Pass by reference: no copy, caller sees changes
void byRef(std::string& s) {
    s += " (modified)";
}

// Pass by const reference: no copy, read-only
void byConstRef(const std::string& s) {
    std::cout << "inside byConstRef: " << s << "
";
}

int main() {
    std::string original = "Hello";

byValue(original);
    std::cout << "after byValue:    " << original << "
"; // unchanged

byRef(original);
    std::cout << "after byRef:      " << original << "
"; // modified

byConstRef(original);

// Pointer example
    int x = 42;
    int* ptr = &x;          // ptr stores the address of x
    std::cout << "x via pointer: " << *ptr << "
";
    *ptr = 100;             // dereference to modify
    std::cout << "x after write: " << x << "
";

// Reference example
    int& ref = x;
    ref = 200;              // same as x = 200
    std::cout << "x via ref:     " << x << "
";

return 0;
}