we cants use strings in our course thats why
Perhaps you're on the wrong course then.
Your course seems to be "This course teaches you to run a marathon, but to create a level playing field, we start by breaking everyone's legs".
Your "tutor" is feeding you brain damage that's of little to no use in modern C++.
> we cants use strings in our course thats why
Well then
- replace .length with strlen()
- replace += with strcat()
- replace == with strcmp()