Understanding C++ Constants and Literals

C++ constants and literals are fundamental concepts in the C++ programming language. They represent fixed values that do not change during the execution of a program.

Key Concepts

1. Constants

• Definition: A constant is a variable whose value cannot be changed after it has been initialized.
• Types of Constants:
  • Literal Constants: Fixed values explicitly defined in the code.
  • Defined Constants: Constants defined using the const keyword or #define preprocessor directive.

2. Literals

• Definition: A literal is a notation for a fixed value in the code. It represents data of a specific type.
• Types of Literals:
  • Integer Literals: Whole numbers (e.g., 10, -5, 0).
  • Floating-point Literals: Numbers with a decimal point (e.g., 3.14, -0.001).
  • Character Literals: Single characters enclosed in single quotes (e.g., 'A', 'z').
  • String Literals: A sequence of characters enclosed in double quotes (e.g., "Hello, World!").
  • Boolean Literals: Values representing truth (e.g., true, false).

Examples

Constants Example

const int MAX_SIZE = 100; // MAX_SIZE is a constant integer

Literal Example

int number = 10; // 10 is an integer literal
float pi = 3.14; // 3.14 is a floating-point literal
char letter = 'A'; // 'A' is a character literal
const char* greeting = "Hello"; // "Hello" is a string literal

Conclusion

Constants are fixed values that cannot be altered, while literals are the actual fixed values used in code. Understanding these concepts is crucial for writing reliable and maintainable C++ programs.