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Go here -> Simple DirectMedia Layer
Download SDL-devel-1.2.15-mingw32.tar.gz (Mingw32), since you're using code::blocks on windows

Then read this -> Using SDL: Video (or Simple DirectMedia Layer...

The poster refuses to say which compiler they're using (on any forum), and also refuses to be more specific than "I got some errors".
This is just too much effort to be bothered with.

> my...

Is this you as well?
To load and display a 600*420 bmp file in c - Dev Shed

So which windows based compiler did you use to compile this 20+ year old fossil code?

If you want to compile this code, you need an actual DOS compiler, which generates DOS executable files, which...