What is the worst real-world macros/pre-processor abuse you’ve ever come across?

What is the worst real-world macros/pre-processor abuse you’ve ever come across (please no contrived IOCCC answers *haha*)?

Please add a short snippet or story if it is really entertaining. The goal is to teach something instead of always telling people “never use macros”.

p.s.: I’ve used macros before… but usually I get rid of them eventually when I have a “real” solution (even if the real solution is inlined so it becomes similar to a macro).

Bonus: Give an example where the macro was really was better than a not-macro solution.

Related question: When are C++ macros beneficial?

70 Answers

From memory, it looked something like this:

#define RETURN(result) return (result);}

int myfunction1(args) {
    int x = 0;
    // do something

int myfunction2(args) {
    int y = 0;
    // do something

int myfunction3(args) {
    int z = 0;
    // do something

Yes that’s right, no closing braces in any of the functions. Syntax highlighting was a mess, so he used vi to edit (not vim, it has syntax coloring!)

He was a Russian programmer who had mostly worked in assembly language. He was fanatical about saving as many bytes as possible because he had previously worked on systems with very limited memory. “It was for satellite. Only very few byte, so we use each byte over for many things.” (bit fiddling, reusing machine instruction bytes for their numeric values) When I tried to find out what kinds of satellites, I was only able to get “Orbiting satellite. For making to orbit.”

He had two other quirks: A convex mirror mounted above his monitor “For knowing who is watching”, and an occasional sudden exit from his chair to do a quick ten pushups. He explained this last one as “Compiler found error in code. This is punishment”.

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