Preprocessor Directives and Macros in C

 Preprocessor Directives and Macros in C

The C preprocessor provides directives and macros for code preprocessing before compilation. Macros allow you to define reusable code snippets, while directives control compilation and inclusion of code from other files.

#include <stdio.h>

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

#define PI 3.14159

#ifdef DEBUG

#define DEBUG_PRINT(...) printf(__VA_ARGS__)

#else

#define DEBUG_PRINT(...)

#endif

int main() {

    int num1 = 10;

    int num2 = 20;

    int max = MAX(num1, num2);

    printf("Maximum: %d\n", max);

    double circleArea = PI * 2.5 * 2.5;

    printf("Circle area: %.2f\n", circleArea);

    DEBUG_PRINT("Debug mode is enabled\n");

    return 0;

}