Variables and Types in C++

Last updated: Sat Apr 26 2025

In C++, variables are used to store data, and types define what kind of data a variable can hold. Understanding variables and types is fundamental to writing correct and efficient C++ programs.

Basic Data Types

• int: Integer numbers (e.g., int count = 10;)
• float, double: Floating-point numbers for decimals (e.g., float price = 99.99f;)
• char: Single character (e.g., char grade = 'A';)
• bool: Boolean values (true or false)

Variable Declaration and Initialization

Variables must be declared with a type before they can be used:

int age = 25;
float height = 5.9f;

Uninitialized variables may contain garbage values — always initialize them.

Type Safety and Auto Keyword

C++ is a strongly-typed language. Incorrect type usage can lead to compilation errors or undefined behavior.

You can use auto to let the compiler deduce the type:

auto score = 92; // score is deduced to be an int

Best Practices

Always initialize variables.

Use meaningful variable names.

Prefer auto when the type is obvious or verbose (especially with iterators).