# C Function macro

**[Function macro](https://en.cppreference.com/w/c/preprocessor/replace)** is a preprocessor macro that looks and behaves like a function call. Arguments must be wrapped in parentheses to preserve precedence during substitution. Multi-statement function macros should use `do { ... } while (0)` to ensure proper scoping and require semicolon syntax.

Always parenthesize macro arguments to avoid operator precedence bugs.

## Example

This example demonstrates function macros with proper argument protection and multi-statement wrapping.

```c
// compile: gcc -o funcmacro funcmacro.c
// run: ./funcmacro
// description: function macros look like functions but substitute inline

#include <stdio.h>

#define MAX(a, b) ((a) > (b) ? (a) : (b))

#define PRINT_PAIR(x, y) do { \
    printf("Values: %d, %d\n", (x), (y)); \
    printf("Max: %d\n", MAX((x), (y))); \
} while (0)

int main() {
    int x = 5, y = 3;
    PRINT_PAIR(x, y);
    
    int z = MAX(2 + 3, 4 + 1);  // correct: (2+3) and (4+1), not 2+3 and 4+1
    printf("Result: %d\n", z);
    
    return 0;
}
```