Friend function: Difference between revisions

Revision as of 17:41, 29 September 2019

Revision as of 17:43, 29 September 2019

Line 1:

In [[object-oriented programming]], a '''friend function''', that is a "friend" of a given [[class (computer science)|class]], is a function that is given the same access as methods to private and protected [[data]].

<ref>{{cite book|last=Holzner|first=Steven|title=C++ : Black Book|year=2001|publisher=Coriolis Group|___location=Scottsdale, Ariz.|isbn=1-57610-777-9|page=397|quote=When you declare a function a friend of a class, that the function has access to the internal data members of that object (that is, its protected, and private data members.)}}

</ref>

A friend function is declared by the class that is granting access, so friend functions are part of the class interface, like methods. Friend functions allow alternative syntax to use objects, for instance <code>f(x)</code> instead of <code>x.f()</code>, or <code>g(x,y)</code> instead of <code>x.g(y)</code>. Friend functions have the same implications on [[separation of concerns|encapsulation]] as methods.

A similar concept is that of [[friend class]].