C Constants

🔒 C Constants – Fixed Values in C Programming

In C, constants are fixed values that do not change during the execution of a program. They help keep your code secure and prevent accidental modification of important values.

🔹 Types of Constants

• Literal Constants – Direct values like 100, 'A', 3.14
• Symbolic Constants – Defined using #define
• Constant Variables – Declared using const keyword

📝 Example: Using const Keyword

This example shows how to declare a constant using the const keyword.

#include <stdio.h>

int main() {
    const float PI = 3.14159;
    printf("Value of PI: %.5f\n", PI);

    // PI = 3.14; // ❌ This will cause an error because PI is constant
    return 0;
}
  

📝 Example: Using #define Macro

This example uses a macro to define a symbolic constant.

#include <stdio.h>

#define MAX_USERS 100

int main() {
    printf("The system can support up to %d users.\n", MAX_USERS);
    return 0;
}
  

🎯 Const vs #define

🧠 Quick Tips

• Use const when you need type safety.
• Use #define for global constants or preprocessor configs.

🎉 Practice Task

Try creating constants for gravity (9.8), speed of light, and your lucky number. Print them in a program!