👀 Views: 35 💬 Answers: 1 📅 Created: 2025-06-04

c macros gcc debugging C

I recently switched to I'm working with unexpected behavior when using macros in C, specifically with expressions that involve both arithmetic and logical operations. Here's a simplified version of what I'm trying to achieve: ```c #include <stdio.h> #define IS_POSITIVE(x) (x > 0) #define SQUARE_AND_CHECK(x) (IS_POSITIVE(x) ? (x * x) : 0) int main() { int value = -5; int result = SQUARE_AND_CHECK(value); printf("Result: %d\n", result); return 0; } ``` When I run this code, I expect `result` to be `0` since `value` is negative, but I get `Result: 25`. I suspect that the macro `SQUARE_AND_CHECK` is not being evaluated as I intended. I've tried debugging by replacing the macro with a function: ```c int square_and_check(int x) { return (x > 0) ? (x * x) : 0; } ``` When I use the function instead, the output is correctly `0`. The question seems to be stemming from the way macros expand. I also checked the order of operations, but I’m still puzzled by why this happens. Can anyone explain why the macro behaves this way and suggest a solution? I'm using GCC 11.2.0 on Linux. I've been using C for about a year now. Any suggestions would be helpful.