📌 Definition:

A data type in C specifies the type of data a variable can hold, such as integers, floating-point numbers, characters, etc. It also defines the size, range, and operations allowed on that data.

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🔶 Types of Data Types in C

C language has the following main categories of data types:

1. Primary (Fundamental) Data Types

2. Derived Data Types

3. User-defined Data Types

4. Void Data Type

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✅ 1. Primary (Fundamental) Data Types

These are the basic built-in data types provided by the C language.

Data Type	Size (in bytes)	Format Specifier	Example	Description
int	2 or 4	%d or %i	int a = 10;	Stores integers
float	4	%f	float x = 2.5;	Stores decimal numbers (single precision)
double	8	%lf	double y = 3.14159;	Stores decimal numbers (double precision)
char	1	%c	char ch = 'A';	Stores a single character

⚠️ Size may vary depending on compiler and system (e.g., 32-bit vs 64-bit).

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🔹 Integer Types in Detail

Type	Size (Bytes)	Range (Approx)	Format Specifier
int	4	-2,147,483,648 to 2,147,483,647	%d
short int	2	-32,768 to 32,767	%hd
long int	4 or 8	-2^31 to 2^31-1 or more	%ld
unsigned int	4	0 to 4,294,967,295	%u

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🔹 Floating Point Types

Type	Size (Bytes)	Precision	Format Specifier
float	4	6-7 digits	%f
double	8	15-16 digits	%lf
long double	10 or 12	>16 digits	%Lf

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🔹 Character Type

Type	Size (Bytes)	Range	Format Specifier
char	1	-128 to 127 (signed)	%c
unsigned char	1	0 to 255	%c

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✅ 2. Derived Data Types

These are based on the fundamental data types.

Type	Description	Example
Array	Collection of same data types	int arr[10];
Pointer	Stores memory address of variable	int *ptr = &a;
Function	Returns data after execution	int add(int x, int y);
Structure	Groups different data types	struct Student {int id; char name[20];};

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✅ 3. User-defined Data Types

These are defined by the programmer using built-in types.

Type	Description	Syntax Example
typedef	Creates alias for data type	typedef int Number;
enum	Defines a set of named integer constants	enum Color {RED, GREEN, BLUE};
struct	Combines variables of different types	struct Person {char name[20]; int age;};
union	Similar to struct but shares memory	union Data {int i; float f;};

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✅ 4. Void Data Type

Type	Description	Example
void	Represents absence of value (no return type)	void display();

• Used for:
• Functions with no return (void main())
• Void pointers (void *ptr)

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🧪 Examples in C Code

#include <stdio.h>

int main() {
    int a = 10;
    float b = 5.75;
    char c = 'Z';
    double d = 3.14159265359;

    printf("Integer: %d\n", a);
    printf("Float: %f\n", b);
    printf("Character: %c\n", c);
    printf("Double: %lf\n", d);

    return 0;
}

🖥 Output:

Integer: 10
Float: 5.750000
Character: Z
Double: 3.141593

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📌 Summary Chart

Category	Types
Fundamental	int, float, double, char
Derived	array, pointer, function, structure
User-defined	typedef, enum, struct, union
Special	void