I've just faced a challenge and found this code, I still confused, why does this code output is 1?

Question

https://code.sololearn.com/cEX0mn7EA8Tq/?ref=app

Answer 1

When it checks if(++a < 0), a is incremented. The condition ++a < 0 is false, that's why a is not increased by 3.

You can change it like this to understand it better:

int a = 0;

if(++a == 1) {
cout << "a is 1";
}

# output: a is 1.

a is increased immediately before its value is checked. That's why the condition ++a == 1 is true.

Answer 2

In the if condition a has pre-increment, hence it will become 1 and the expression will finally evaluate to false and therefore the body of the condition will not be executed. At the end a will be 1.

Answer 3

Thx Anna