Old C++ code dont compile

Question

I found an old game programming book in my cabinet
and thers a code for a simple 2d game loop
https://code.sololearn.com/cOmz89EalBUy/#cpp

the .exe file on the cd is working, but i cant compile the code in visual studio
the function draw_string dont accepts strings

maybe someone could try to compile this and tell me how to fix this in the new vs version

Answer 1

The dots are moving on my screen and clear screen is clearing the screen.

Not sure what else it could be.
The only things I changed to make the code compile on visual studio was change the Draw_String 3rd parameter to a const char*, void main into int main and kbhit into _kbhit.

Answer 2

A string literal like "abc" is a const char[N] which converts to a const char* the first chance it gets and it is placed in the read only parts of memory.

char* s = "abc" is therefore illegal C++.
It would imply that s is pointing to a modifiable string which it is not, even though some compilers allow this anyway but it's gonna crash if you try to write.
( -Wwrite-strings ) will emit a warning.
Visual studio does not allow this conversion to happen though.

Your Draw_String is defined as
inline void Draw_String( int x, int y, char *string );
But it recieves a const char* instead and this conversion to a char* is not allowed.

The correct definition should be
inline void Draw_String( int x, int y, const char *string );

kbhit might also complain. _kbhit fixes it for me.
Check out
https://docs.microsoft.com/en-us/windows/win32/api/winuser/nf-winuser-getkeyboardstate
instead as a possible alternative.

Answer 3

works with const char, but not like the .exe on the disk
the dots are not moving and the clear_screen dont work

Answer 4

Error found!
I made a new empty Project in VS and now its working fine