rectangle_reference.cpp (Rectangle code using functions with arguments passed by reference)
#include<iostream>
using namespace std;
class Rectangle
{
public:
int width;
int height;
};
void print_rectangle(Rectangle);
// added '&' to denote call by reference. The system will now pass another name
// of the input variable to the function, instead of a copy of the variable.
void grow_rectangle(Rectangle&);
void shrink_rectangle(Rectangle&);
int main() {
Rectangle ra;
ra.width = 16;
ra.height = 9;
print_rectangle(ra);
// The argument for the function call remains unchanged. One can think of
// call by reference as creating a new name for the argument variable,
// as opposed to call by value, which creates a copy of the argument variable
grow_rectangle(ra);
print_rectangle(ra);
shrink_rectangle(ra);
print_rectangle(ra);
return 0;
}
// Since we are not modifying the rectangle,
// we can simply make a call by value.
void print_rectangle(Rectangle r)
{
for(int i = 0; i < r.height; i++)
{
for(int j = 0; j < r.width; j++)
{
cout << "*";
}
cout << endl;
}
cout << endl;
}
// The way in which class members are accessed also remains unchanged.
// We do not return the modified object, since the modifications were
// done on the original object itself.
void grow_rectangle(Rectangle& r)
{
r.width += 2;
r.height += 2;
}
void shrink_rectangle(Rectangle& r)
{
r.width -= 2;
r.height -= 2;
}
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