Data Types in C Programming

In C programming, data types are declarations for variables. This determines the type and size of data associated with variables. For example,

int myVar;

Here, myVar is a variable of int (integer) type. The size of int is 4 bytes.

Basic types

Here's a table containing commonly used types in C programming for quick access.

Type	Size (bytes)	Format Specifier
int	at least 2, usually 4	%d, %i
char	1	%c
float	4	%f
double	8	%lf
short int	2 usually	%hd
unsigned int	at least 2, usually 4	%u
long int	at least 4, usually 8	%ld, %li
long long int	at least 8	%lld, %lli
unsigned long int	at least 4	%lu
unsigned long long int	at least 8	%llu
signed char	1	%c
unsigned char	1	%c
long double	at least 10, usually 12 or 16	%Lf

int

Integers are whole numbers that can have both zero, positive and negative values but no decimal values. For example: 0, -5, 10

We can use int for declaring an integer variable.

int id;

Here, id is a variable of type integer.

You can declare multiple variables at once in C programming. For example: int id, age;

The size of int is usually 4 bytes (32 bits). And, it can take 2 ³² distinct states from -2147483648 to 2147483647.

float and double

float and double are used to hold real numbers.

float salary;

double price;

In C, floating-point numbers can also be represented in exponential. For example,

float normalizationFactor = 22.442e2;

What's the difference between float and double?

The size of float (single precision float data type) is 4 bytes. And the size of double (double precision float data type) is 8 bytes.

char

Keyword char is used for declaring character type variables. For example:char test = 'h';

The size of the character variable is 1 byte.

void

void is an incomplete type. It means "nothing" or "no type". You can think of void as absent.

For example, if a function is not returning anything, its return type should be void.

Note that, you cannot create variables of void type.

short and long

If you need to use a large number, you can use a type specifier long. Here's how:

long a;

long long b;

long double c;

Here variables a and b can store integer values. And, c can store a floating-point number.

If you are sure, only a small integer ([−32,767, +32,767] range) will be used, you can use short.

short d;

You can always check the size of a variable using the sizeof() operator.

#include <stdio.h>      

int main() {

  short a;

  long b;

  long long c;

  long double d;

  printf("size of short = %d bytes\n", sizeof(a));

  printf("size of long = %d bytes\n", sizeof(b));

  printf("size of long long = %d bytes\n", sizeof(c));

  printf("size of long double= %d bytes\n", sizeof(d));

  return 0;

}

signed and unsigned

In C, signed and unsigned are type modifiers. You can alter the data storage of a data type by using them. For example,

unsigned int x;

int y;

Here, the variable x can hold only zero and positive values because we have used the unsigned modifier.

Considering the size of int is 4 bytes, variable y can hold values from -2³¹ to -2³¹-1, whereas variable x can hold values from 0 to 2³²-1.

Other data types defined in C programming are:

• bool Type
• Enumerated type
• Complex types

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