What Is C Data Type?


Heather Bennett

When programming in C, data types are an essential concept to understand. They define the type and size of data that a variable can hold.

In C, there are several built-in data types that you can use to declare variables and manipulate data. Let’s explore these data types in detail.

Basic Data Types

In C, the basic data types include:

  • int: This is used to store integer values. It typically uses four bytes of memory.
  • float: This is used to store floating-point numbers with single precision.

    It typically uses four bytes of memory.

  • double: This is used to store floating-point numbers with double precision. It typically uses eight bytes of memory.
  • char: This is used to store individual characters. It typically uses one byte of memory.

Data Modifiers

C also provides several modifiers that can be applied to the basic data types:

  • short: This modifier reduces the size of an int by half, typically using two bytes of memory.
  • long: This modifier increases the size of an int or double, typically using eight bytes for long int and ten bytes for long double.
  • signed: This modifier allows both positive and negative values for an int or char (which is signed by default).
  • unsigned: This modifier allows only non-negative values for an int or char.

User-Defined Data Types

In addition to the built-in data types, C also allows you to create your own data types using struct and enum.


A struct is a collection of variables of different data types grouped together under a single name. It allows you to create more complex data structures. Here’s an example:

struct Person {
  char name[50];
  int age;
  float height;

In the above example, we have defined a struct called Person that consists of three variables: name (an array of characters), age (an integer), and height (a float).


An enum is a user-defined data type that assigns names to integral constants, making the code more readable and maintainable. Here’s an example:

enum Day {

In the above example, we have defined an enum called Day with seven constants representing each day of the week.

Type Modifiers and Qualifiers

C also provides type modifiers and qualifiers that further define the behavior and properties of data types:

  • const: This qualifier specifies that a variable’s value cannot be changed once it is assigned.
  • volatile: This qualifier indicates that a variable can be modified by something external to the program, such as hardware.
  • restrict: This qualifier is used as a hint to the compiler for optimization purposes.


In summary, data types in C are crucial for declaring variables and manipulating data. Understanding the basic data types, modifiers, user-defined data types like struct and enum, as well as type modifiers and qualifiers, is essential for writing effective and efficient C programs.

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