Can anyone explain what is pure c code?

Question

I was learning operating system and there came a thing where source code is converted to pure c code by preprocessor and I am not clear with the pure c code concept. Even a simple definition will be appreciated. Thank you.

Answer 1

I think "pure" is not a technical term here (maybe I am wrong).

If you have

#define X 5
int main () {
return X;
}

then after the preprocessor runs we have C code that looks like

int main () {
return 5;
}

So the same code, but all the C preprocessor directives are gone. This can get pretty tricky with things like macros and #if, #ifdef, #pragma etc...

I think this is what the author means by "pure". The C preprocessor is a dumb copy-paste machine and it takes C code with preprocessor directives and produces C code without.