Data Types in C

Data type refers to the type of data. We have already learnt about variables in C which refers to the memory location of any data stored but what kind of data that memory location can store , this is determined by assigning a type to the variable using some keywords called data types. It determines the space occupied in the memory location , type of values that can be stored in that memory location and much more.
In C programming language variables are declared before it can be used in the program, and data types are used to define a variable before its use.

Classification of Data Types in C-

C data types are classified into four categories –

Category	Types
Basic Data Type	int,char,double,float
Derived Data Type	Array,structure,pointer,union
Void	void
Enumerated data type	enum

1.C Basic Data Types-

C basic data type are arithmetic data types and int,char,double,float comes under this category.

1.1 Integer data type In C-

Values Stored	Integer values are stored
Keyword used	int
Storage size	2 or 4 byte
Value range	-32768 to +32767 (for 2 byte) 2,147,483,648 to +2,147,483,647 (for 4 byte)

Points to remember-

• Decimal values cannot be stored in an int data type.


• If we store decimal values in an int type variable then we will get only whole numbers and decimal values will be truncated

1.2 Char Data type in C-

Values Stored	Only a single character can be stored
Keyword used	char
Storage size	1 byte
Value range	128 to 127 or 0 to 255

1.3 Floating Data type in C

Floating data type is further classified into 3 categories – 1. float   2. double   3. long double

1.3.1 float data type-

Values Stored	Decimal values are stored
Keyword used	float
Storage size	4 byte
Value range	1.2E-38 to 3.4E+38
Precision	up to 6 decimal places

1.3.2 Double data type-

Values Stored	Decimal values are stored
Keyword used	double
Storage size	8 byte
Value range	2.3E-308 to 1.7E+308
Precision	upto 15 decimal places

1.3.3 long double data type-

Values Stored	Decimal values are stored
Keyword used	long double
Storage size	10 byte
Value range	3.4E-4932 to 1.1E+4932
Precision	up to 19 decimal places

How to get the Exact size of a datatype on any platform in C-

In C programming language you can use size of operator to get the exact size of any data type on that platform.
For Example- sizeof(int)

2. Derived data type in C-

Arrays , structure , Union are the derived datatypes in C. We will learn in detail about derived data types in our upcoming tutorials.

3.Void data type in C-

void data type is used for no value available.
Keyword used– void
Void data type is used to represent a null value. We will learn more about its uses in our upcoming tutorials.

4. Enumerated data type

With its help you can define your own data type, enum is a user defined data type. It consist a list of named integer type constant.
Syntax-

enum new_datatype_name {value1, value2, value3, value4,….. valuen}

By default the first value in the braces (value1) is assigned a numeric value 0 ,value 2 is assigned 1, value 3 is 2 and so on..
But if we assign some integer value to the very first element in the braces say value1=20 then the values assigned to the next elements will be Value2=21, value3=23 and so on..
The above enums are similar to defining integer constants like-

#define value1 0
#define value2 1
#define value3 2
and so on…

For Example-

enum weekdays{mon,tue,wed,thu,fri,sat,sun};
enum weekdays wd;

In above Example-

enum weekdays{mon,tue,wed,thu,fri,sat,sun};

this line creates a new data type called weekdays.This new data type has 7 values written in the braces.As explained above the numerically assigned values for mon is 0,tue is 1,wed is 2 and so on..

enum weekdays wd;

This statement declares a new variable wd of type weekdays and wd can be initialized with any of the values given in the new data type braces like-
wd = tue;
If we write code

printf(“%d”,wd);

It will print the numeric value of wd which is 1.

A simple C program printing the numeric values of enum-

#include <stdio.h>
void main()
{
int n;
enum weekdays {mon,tue,wed,thu,fri,sat,sun };

  for(n=mon;n<=sun;n++)
      printf("%d",n);
}

Output-

0123456

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