C Data Types

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The data type specifies the size and type of information the variable will store

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

• More information about C Format Specifiers

int C Numbers

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.

int id, age;

The size of int is usually 4 bytes (32 bits). And, it can take 232 distinct states from -2147483648 to 2147483647.

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float and double C Numbers

float and double are used to hold real numbers.

float salary;
double price;

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

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.

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char C Chars

Keyword char is used for declaring character type variables.

char test = 'h';

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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

Warning

Note that, you cannot create variables of void type.

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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.

short

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

short d;

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signed and unsigned

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

• signed - allows for storage of both positive and negative numbers
• unsigned - allows for storage of only positive numbers

// valid codes
unsigned int x = 35;
int y = -35;  // signed int
int z = 36;  // signed int
 
// invalid code: unsigned int cannot hold negative integers
unsigned int num = -35;

Here, the variables x and num 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