IF statement with number in condition (c++)

Question

Can you please explain, how come you can use integer in IF condition?
What is tested here? How it works?
And what it is even good for? Thanks!

For example:

if (28)
cout << x;
else
cout << y;

Answer 1

if() tests for a true/false condition. A boolean is usually used (or something which equates to a true false condition) But since a boolean (in c) is just an integer range limited between 0 and 1 any integer can be substituted in its place.

Using the if statement like you have has no use as any non zero number is considered true as a result the else statement will never be executed.

Answer 2

Yes, Only 0 is considered false.

Answer 3

The more you know, thanks Vlad!

From: https://en.m.wikipedia.org/wiki/Boolean_data_type

C++ has a separate Boolean data type bool, but with automatic conversions from scalar and pointer values that are very similar to those of C.

Answer 4

@jay
It's not like booleans are integers. It's that if() expects an integer (because C didn't have booleans for a long time) so if you feed it a boolean it automatically converts it into an integer.

@rudolf
while(i-- > 0)
There, done with a boolean.

Answer 5

@jay
C (since C99) also has a boolean type. It's called _Bool. And you can use the bool, true and false keywords using stdbool.h

Answer 6

Great thanks, so any non-zero is True? Even the negative numbers?
I must have missed that in C++ course.. :(