What is a data type in c.

In C programming, data types are declarations for variables. This determines the type and size of data associated with variables. For example,
  1. 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.
TypeSize (bytes)Format Specifier
intat least 2, usually 4%d
short int2 usually%hd
unsigned intat least 2, usually 4%u
long intat least 4, usually 8%li
long long intat least 8%lli
unsigned long intat least 4%lu
unsigned long long intat least 8%llu
signed char1%c
unsigned char1%c
long doubleat least 10, usually 12 or 16%Lf


Integers are whole numbers that can have both zero, positive and negative values but no decimal values. For example, 0-510
We can use int for declaring an integer variable.
  1. int id;
Here, id is a variable of type integer.
You can declare multiple variables at once in C programming. For example,
  1. int id, age;
The size of int is usually 4 bytes (32 bits). And, it can take 232 distinct states from -2147483648 to 2147483647.

float and double

float and double are used to hold real numbers.
  1. float salary;
  2. double price;
In C, floating-point numbers can also be represented in exponential. For example,

  1. 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.


Keyword char is used for declaring character type variables. For example,
  1. char test = 'h';
The size of the character variable is 1 byte.


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:
  1. long a;
  2. long long b;
  3. 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.
  1. #include <stdio.h>
  2. int main() {
  3. short a;
  4. long b;
  5. long long c;
  6. long double d;
  7. printf("size of short = %d bytes\n", sizeof(a));
  8. printf("size of long = %d bytes\n", sizeof(b));
  9. printf("size of long long = %d bytes\n", sizeof(c));
  10. printf("size of long double= %d bytes\n", sizeof(d));
  11. return 0;
  12. }

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,
  1. unsigned int x;
  2. int y;
Here, the variable x can hold only zero and positive values because we have used the 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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