C: Variables and Constants

Learn the basic methods of storing and managing data in memory.

1. Variables

A variable is a name assigned to a memory space where a value can be stored.

int age = 25;       // Integer variable
float pi = 3.14f;   // Floating-point variable
char grade = 'A';   // Character variable

2. Constants

Data that once defined, cannot have its value changed.

• const keyword: const int MAX = 100;
• #define macro: #define PI 3.14159

📏 Naming Conventions

• Only alphanumeric characters and underscores (_) are allowed.
• Cannot start with a digit.
• Case-sensitive (age and Age are different).
• Reserved words (e.g., int, return) cannot be used as names.