Pass By Reference
In the examples from the previous page, we used normal variables when we passed parameters to a function.
You can also pass a reference to the function.
This can be useful when you need to change the value of the argument(s):
Example
void changeValue(int &num) {
num = 50;
}
int main() {
int value = 10;
changeValue(value); // Call the function and
change the value to 50
cout << value;
return 0;
}
Example
void swapNums(int &x, int &y) {
int z = x;
x = y;
y = z;
}
int main() {
int firstNum = 10;
int secondNum = 20;
cout <<
"Before swap: " << "\n";
cout << firstNum << secondNum << "\n";
// Call the function, which will change the values of firstNum
and secondNum
swapNums(firstNum, secondNum);
cout << "After swap:
" << "\n";
cout << firstNum << secondNum << "\n";
return 0;
}
Example
void modifyStr(string &str) {
str += " World!";
}
int main() {
string greeting = "Hello";
modifyStr(greeting);
cout <<
greeting;
return 0;
}
