For loop with condition only

Question

Can someone explain how the for(; A--;) loop works. It doesn't have any increments, so shouldn't it run forever ?

int main(){
int A, B;

cout << "Anna t\x84htien m\x84\x84r\x84: "; //Give ammount of stars: 
cin >>A;
cout << endl;

for(; A--;){
    for(B = 0; A >= B; B++){
        cout << "* ";
    }
    cout << endl;
}

return 0;
}

Answer 1

A for loop runs for as long as its condition holds true. A-- is equivalent to A-- != 0, so this is how long it's going to run.

One thing that is possibly nice to know is that a for loop can contain a lot more than mere incremental operations. Usually, it's something like ++i, but that is no necessity. In school, you might not learn about how general for loops actually are, though.