C – Variable Data Types

Data types in c give you abilities to choose exact data type of variable for your operation. The type of a variable determines how much space it occupies in storage and how the bit pattern stored is interpreted.

The Data types in C can be classified as follows −

Data Types

S.N. Data Types & Description
1 Basic Types

They are arithmetic types and are further classified into: (a) integer types and (b) floating-point types.

2 Enumerated types

They are again arithmetic types and they are used to define variables that can only assign certain discrete integer values throughout the program.

3 The type void

The type specifier void indicates that no value is available.

4 Derived types

They include (a) Pointer types, (b) Array types, (c) Structure types, (d) Union types and (e) Function types.

The array types and structure types are referred collectively as the aggregate types but the basic difference is that array is a collection of homogeneous data type and structure is a collection of the heterogeneous data type. The type of a function specifies the type of the function’s return value. Pointer and other Data types will be discussed in the upcoming post.

Integer Types

The following table provides the details of standard integer types with their storage sizes and value ranges −

Type Storage size Value range
char 1 byte -128 to 127 or 0 to 255
unsigned char 1 byte 0 to 255
signed char 1 byte -128 to 127
int 2 or 4 bytes -32,768 to 32,767 or -2,147,483,648 to 2,147,483,647
unsigned int 2 or 4 bytes 0 to 65,535 or 0 to 4,294,967,295
short 2 bytes -32,768 to 32,767
unsigned short 2 bytes 0 to 65,535
long 4 bytes -2,147,483,648 to 2,147,483,647
unsigned long 4 bytes 0 to 4,294,967,295

To get the exact size of a type or a variable on a particular platform, you can use the sizeof operator. The expressions sizeof(type) field the storage size of the object or type in bytes. Given below is an example to get the size of int type on any machine −

#include<stdio.h>
#include<limits.h>

 main()
{

   printf("Storage size for int : %d \n",sizeof(int));
   
   return 0;
}

When you compile and execute the above program, it produces the following result on Linux −

Storage size for int : 4

Floating-Point Types

The following table provides the details of standard floating-point data types with storage sizes and value ranges and their precision −

Type Storage size Value range Precision
float 4 byte 1.2E-38 to 3.4E+38 6 decimal places
double 8 byte 2.3E-308 to 1.7E+308 15 decimal places
long double 10 byte 3.4E-4932 to 1.1E+4932 19 decimal places

The header file float.h defines macros that allow you to use these values and other details about the binary representation of real numbers in your programs. The following example prints the storage space taken by a float type and its range values −

 

#include <stdio.h>
#include <float.h>
int main()
{
     printf("Storage size for float : %d \n", sizeof(float));
     printf("Minimum float positive value: %E\n", FLT_MIN );
     printf("Maximum float positive value: %E\n", FLT_MAX );
     printf("Precision value: %d\n", FLT_DIG );
     return 0;
}

When you compile and execute the above program, it produces the following result on Linux −

Storage size for float : 4
Minimum float positive value: 1.175494E-38
Maximum float positive value: 3.402823E+38
Precision value: 6

The void Data Type

The void Data type specifies that no value is available. It is used in three kinds of situations −

S.N. Data Types & Description
1 Function returns as void

There are various functions in C which do not return any value or you can say they return void. A function with no return value has the return type as void. For example, void exit (int status);

2 Function arguments as void

There are various functions in C which do not accept any parameter. A function with no parameter can accept a void. For example, int rand(void);

3 Pointers to void

A pointer of type void * represents the address of an object, but not its type. For example, a memory allocation function void *malloc( size_t size ); returns a pointer to void which can be casted to any data type.

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Subroto Mondal

Chief Coordinator HR&CR
I like Programming and New Technologies. And work with Linux.

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