Data Types in C

Data types form the foundation of data representation in C. Every variable in C must be associated with a data type that defines the kind of value it can store and how the compiler handles it.

• Data types define memory allocation, value range, and valid operations on a variable.
• Understanding data types is essential for writing correct and efficient C programs.

Classification of Data Types in C

Data types in C are broadly classified into three categories:

Primitive Data Types

Primitive data types are the basic built-in data types in C used to store simple values like integers, characters, and floating-point numbers.

Integer Data Type

• Stores whole numbers (positive, negative, or zero).
• We use int keyword to declare the integer variable:
• Size: typically 4 bytes, Range: -2,147,483,648 to 2,147,483,647.
• Format specifier: %d.

Format specifiers are the symbols that are used for printing and scanning values of given data types.

var = 22

Character Data Type

• Stores a single character (like ‘A’, ‘b’, or ‘5’).
• Size: typically 1 byte, Range: -128 to 127 (signed by default).
• Format specifier: %c.

ch = A

Float Data Type

• Stores decimal numbers (numbers with fractional part).
• Size: typically 4 bytes, Approximate range: 3.4e-38 to 3.4e+38.
• Format specifier: %f.

val = 12.450000

Double Data Type

• Stores decimal numbers with more precision than float.
• Size: typically 8 bytes, Approximate range: 1.7e-308 to 1.7e+308.
• Format specifier: %lf.

val = 1.452100

Void Data Type

• Represents no value or empty type.
• Used in functions that do not return any value.
• Can also be used for generic pointers (void *) in memory operations.

Hello, welcome!

Derived Data Types in C

Derived data types are created from primitive data types.

Arrays

An array stores multiple values of the same type in contiguous memory locations.

int arr[5] = {1, 2, 3, 4, 5};

Pointers

A pointer stores the memory address of another variable.

int x = 10;
int *ptr = &x;

Functions

Functions are also considered derived types based on return type and parameters.

int add(int a, int b) {
return a + b;
}

User Defined Data Types in C

User-defined data types allow programmers to create custom data structures.

Structure (struct)

A structure groups related variables under one name

struct Student {
char name[50];
int age;
};

Union

A union allows multiple members to share the same memory location.

union Data {
int i;
float f;
};

Enumeration (enum)

Enum is used to define named integer constants.

enum Day {
MON, TUE, WED, THU, FRI, SAT, SUN
};

Size of Data Types in C

The size of the data types in C is dependent on the size of the architecture, so we cannot define the universal size of the data types. For that, the C language provides the sizeof() operator to check the size of the data types.

The size of int: 4
The size of char: 1
The size of float: 4
The size of double: 8

Different data types also have different ranges up to which can vary from compiler to compiler. If you want to know more about ranges refer to this Ranges of Datatypes in C.

Note: The long, short, signed and unsigned are datatype modifier that can be used with some primitive data types to change the size or length of the datatype.

Related Article

• Literals
• Type conversion