C Data Types

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 int main()

signed and unsigned

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

// 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 -2 31 to 2 31 -1 , whereas variable x can hold values from 0 to 2 32 -1 .

Derived Data Types

Data types that are derived from fundamental data types are derived types. For example: arrays, pointers, function types, structures, etc.

We will learn about these derived data types in later tutorials.

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