What overloaded operator is called in an if condition?

Question

ifstream is;
...
...

if (is) { // What overloaded operater of **is** object is called here
....
}

What overloaded operator of is object is called ?

possible duplicate of [What is the meaning of "operator bool() const" in C++](http://stackoverflow.com/questions/4600295/what-is-the-meaning-of-operator-bool-const-in-c) — shauryachats, Mar 20 '15 at 12:37
@volerag: Only if you already know the answer of the question -- "What overloaded operator is called" -- "`operator bool()`". Thus, the link is related, but the question is not duplicate. — DevSolar, Mar 20 '15 at 12:41
Well, @DevSolar I think I answered his question *as well as* called it duplicate. Nothing wrong in that, right? — shauryachats, Mar 20 '15 at 12:45

score 6 · Answer 1 · answered Mar 20 '15 at 12:34

6

Since C++11, there is a conversion operator to bool:

explicit operator bool() const;

Before that, there was a conversion operator to void*:

operator void*() const;

the latter evaluates to true for any non-null pointer and false otherwise.

answered Mar 20 '15 at 12:34

juanchopanza

And it's worth noting, that if you are writing code where you can't use `operator bool()`, you should read up on the safe bool idiom. – Bill Lynch Mar 20 '15 at 12:42

DevSolar · Answer 2 · 2015-03-20T12:45:11.637

2

This is functionally equivalent to:

if ( ! is.fail() )

edited Mar 20 '15 at 12:45

answered Mar 20 '15 at 12:37

DevSolar

2 Answers2