Why Return a Reference from the Copy Assignment Operator in C ?

Copy Assignment Operator: Why Reference as Return Type?

Returning a reference or const reference from the copy assignment operator is a fundamental concept in C . This practice ensures efficient object assignment and avoids unnecessary copying. Unlike returning a copy, returning a reference allows for minimal work by directly copying values between objects.

Consider the following code snippet:

A a1(param);
A a2 = a1;
A a3;

a3 = a2; // Assignment operator

With an operator= defined as:

A A::operator=(const A& a)
{
    if (this == &a)
        return *this;
    param = a.param;
    return *this;
}

Returning a reference eliminates the overhead of calling a constructor and destructor for every assignment. Instead, it simply updates the values in memory.

In contrast, returning a copy would require creating a new object, copying values from the assigned object, and destroying the temporary copy after each assignment. This wasted overhead becomes especially noticeable in complex assignments like the chain a = b = c.

By returning a reference, the copy assignment operator:

• Minimizes processing time
• Prevents unnecessary object creation and destruction
• Maintains encapsulation and ensures object integrity

The above is the detailed content of Why Return a Reference from the Copy Assignment Operator in C ?. For more information, please follow other related articles on the PHP Chinese website!