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Data Types in C

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Introduction

In C programming, data types are one of the most important concepts. They define what kind of data a variable can store, how much memory it occupies, and what operations can be performed on it.

Understanding data types is essential for writing efficient, accurate, and error-free programs.

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What are Data Types in C?

A data type specifies:

• The type of data (integer, character, decimal, etc.)
• The memory size required
• The range of values that can be stored

👉 In simple terms:
Data types tell the compiler what kind of data you are working with.

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Categories of Data Types in C

C data types are broadly classified into:

1. Basic (Primary) Data Types
2. Type Modifiers
3. Derived Data Types
4. User-defined Data Types

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1. Basic (Primary) Data Types

These are the fundamental data types:

Data Type	Description	Example	Size (Approx)
int	Integer numbers	10, -5	4 bytes
float	Decimal numbers	3.14	4 bytes
char	Single character	'A'	1 byte
double	High precision decimal	3.14159	8 bytes
void	No value	—	0 byte

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2. Type Modifiers

Modifiers change the size or range of basic data types:

Modifier	Description	Example
short	Smaller integer	short int a;
long	Larger integer	long int b;
long long	Very large integer	long long int c;
signed	Positive & negative values	signed int d;
unsigned	Only positive values	unsigned int e;

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Example Using Modifiers

#include <stdio.h>

int main() {
    short int a = 10;
    long int b = 100000;
    unsigned int c = 50;

    printf("Short = %d\n", a);
    printf("Long = %ld\n", b);
    printf("Unsigned = %u\n", c);

    return 0;
}

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3. Derived Data Types

These are created from basic data types:

Type	Description
Arrays	Collection of elements
Pointers	Store memory address
Functions	Block of reusable code

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Example:

int arr[5];     // Array
int *ptr;       // Pointer

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4. User-Defined Data Types

These are created by the programmer:

Type	Description
struct	Group of different data types
union	Shares memory among members
enum	Named integer constants
typedef	Create new name for data type

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Example:

struct Student {
    int id;
    char name[20];
};

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Complete Summary Table

Category	Types Included
Basic	int, float, char, double, void
Modifiers	short, long, signed, unsigned
Derived	array, pointer, function
User-defined	struct, union, enum, typedef

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Example Program Using Data Types

#include <stdio.h>

int main() {
    int age = 18;
    float marks = 85.5;
    char grade = 'A';
    double pi = 3.14159;

    printf("Age = %d\n", age);
    printf("Marks = %f\n", marks);
    printf("Grade = %c\n", grade);
    printf("Pi = %lf\n", pi);

    return 0;
}

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Output

Age = 18
Marks = 85.500000
Grade = A
Pi = 3.141590

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Format Specifiers

Data Type	Format Specifier
int	%d
float	%f
char	%c
double	%lf
unsigned int	%u
long int	%ld

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Common Mistakes

• ❌ Using wrong data type
• ❌ Incorrect format specifier
• ❌ Not initializing variables
• ❌ Confusing float and double

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Pro Tips

• ✔ Use appropriate data types for memory efficiency
• ✔ Use double for high precision calculations
• ✔ Always initialize variables
• ✔ Practice writing programs using different data types

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Conclusion

Data types are the foundation of C programming. They help you store and manipulate data effectively. Mastering data types will make your programming journey much easier and more efficient.

👉 This article is part of Dharani Tech Edu Hub — where learning programming is made simple and practical.