C Data Types

C Data Types (Complete Tutorial: Beginner → Advanced)

In C Data Types define:

what kind of data a variable can store
how much memory it occupies
what operations can be performed

They are one of the most important fundamentals for programming, exams, and interviews.

What is a Data Type?

A data type specifies the type of value a variable can hold.

Classification of Data Types in C

They are divided into four main categories:

Basic (Primitive) Data Types
Derived Data Types
User-Defined Data Types
Void Data Type

Basic (Primitive) Data Types

These are the core data types in C.

`int` – Integer

Stores whole numbers.

Size: usually 4 bytes
Range: −2,147,483,648 to 2,147,483,647

`float` – Floating Point

Stores decimal numbers (single precision).

Size: 4 bytes
Precision: ~6 digits

`double` – Double Precision

Stores large decimal numbers.

Size: 8 bytes
Precision: ~15 digits

`char` – Character

Stores single character.

Size: 1 byte
Stored as ASCII value

Type Modifiers (Extended Data Types)

Used to modify range and size.

Modifier	Example
`short`	`short int a;`
`long`	`long int b;`
`signed`	`signed char c;`
`unsigned`	`unsigned int d;`

Derived Data Types

Derived from basic types.

Array

Pointer

Function

User-Defined Data Types

Created by programmers.

`struct`

`union`

`enum`

`typedef`

Void Data Type

Represents no value.

Function Returning Nothing

Void Pointer

Can point to any data type

Boolean Data Type (C99)

true → 1
false → 0

Size of Data Types (Example)

Common Format Specifiers

Data Type	Specifier
`int`	`%d`
`float`	`%f`
`double`	`%lf`
`char`	`%c`
`string`	`%s`

Common Mistakes

Using wrong format specifier
Assuming same size on all systems
Confusing float and double
Forgetting & in scanf()

Interview Questions (Must Prepare)

What are data types in Ity, ?
Difference between int, float, and double
What is derived data type?
Difference between struct and union
What is void data type?
Size of char in C?

Summary

Data types define type, size & range of data
It has basic, derived, and user-defined types
Correct data type improves performance & safety
Fundamental for DSA, system programming & interviews