C - Constants

Constants represent values that should not change.

Ways to Define Constants

• const variables (type-safe): const int MAX = 100;
• Preprocessor macros (no type checking): #define MAX 100

Examples

#include <stdio.h>

#define BUFFER 1024
const double PI = 3.141592653589793;

int main(void) {
  printf("%d %.2f\n", BUFFER, PI);
}

Common Pitfalls

• Writing to a const variable (compiler error).
• Macros lack scope and type safety; prefer const when possible.