C++ Programming - References - Discussion

I agree @Singh,

But then shouldn't statement #2 be "the type of the function must be an L-value"?

That's what it means to be on the LEFT side of an assignment statement?

Great explanation @Singh.

Thanks.

A C++ program can be made easier to read and maintain by using references rather than pointers. A C++ function can return a reference in a similar way as it returns a pointer.

When a function returns a reference, it returns an implicit pointer to its return value. This way, a function can be used on the left side of an assignment statement.

#include <iostream>
#include <ctime>

using namespace std;

double vals[] = {10.1, 12.6, 33.1, 24.1, 50.0};

double& setValues( int i )
{
return vals[i]; // return a reference to the ith element.
}

// main function to call above defined function.

int main ()
{

cout << "Value before change" << endl;
for ( int i = 0; i < 5; i++ )
{
cout << "vals[" << i << "] = ";
cout << vals[i] << endl;
}

setValues(1) = 20.23; // change 2nd element
setValues(3) = 70.8; // change 4th element

cout << "Value after change" << endl;
for ( int i = 0; i < 5; i++ )
{
cout << "vals[" << i << "] = ";
cout << vals[i] << endl;
}
return 0;
}

Reference must be initialize at the time of declaration. Therefore R-value required.

E.g: int &z = a(R-value).

When we are declare a function we must specifies there return type because the function always return value by default they return int value.

Reference must be initialize at the time of definition. Therefore it must be at R-value place.

Somebody can write an example.

Reference value because call by ref reflects changes in original arguments.

2. The type of the function must be a R-value.

What is R-value mean?