i dont understand decreament??

Answer 1

It means reduce. So if you see i--(which can also be written as i=i-1) means reduce i by 1 after you finish this statement. Or if you see --i, it means, reduce i by 1 first then finish this statement

Answer 2

an example for decreament

Answer 3

int a = 2;
if(a < 5)
a--;
cout << a;
this will print 1

Answer 4

and example of --a

Answer 5

int a = 2;
if(a < 5)
cout << a--;
cout << a;
the code above will print 2 then 1

int a = 2;
if(a < 5)
cout << --a;
cout << a;
This code will print 1 then 1.