Why this answer is correct?

Question

I got that question in C++ chalange and I have no idea why the correct answer is 0. I thought that the answer is 17.5 but no.

What is the output of this code?

int function (double x) {
if (x > 0) {
function (x - 2.5);
}else {
return x;
}
}
int Main () {
cout << function (20.0);

Answer: 0

Sorry for bad gramma :)

Answer 1

The function calls itself>
Check the following code and I think that you will understand..

https://code.sololearn.com/cEFndo1hoops/#cpp

Answer 2

Well that was helpful, thanks you very much. I didn't know that the function will go over and over until march the if condition.