Different Data Types in ‘C’

8/6/2019 Different Data Types in C

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Submitted by :Manish Mann

ECE/09/128


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` Data Type: set of values together with a set of

operations is called a data type

` Data types are used to store various types of data

that is processed by program.

` Data type attaches with variable to determine the

number of bytes to be allocate to variable and

valid operations which can be performed on thatvariable.


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` C data can be classified into four categories:

Fundamental data types

Data type modifiers

Derived data types

UserDefined data types


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` Fundamental data types are those that are notcomposed of any other data types.

Five types of fundamental data types are:-

1. int data type (for integers):

Examples: 0

-6728

91

No commas are used within an integer.Size: 2 bytes

Range: -32768 to 32767


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2. char data type (forcharacters):

The smallest integral data type.

Used for characters: letters, digits, and special symbols.

Each character is enclosed in single quotes.

Examples: 'A,'a', '0', '*', '+', '$', '&.A blank space is a character and is written ' ', with a space.

Size : 1 byte

Range : -128 to 127

3. float data type (for floating point numbers):It represents any real number.Size : 4 bytesRange: 3.4 * 10-38 to 3.4 * 1038 -1


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4. double data type (for double precision floatingpoint

numbers):

it is used to define BIG floating point numbers.

It reserves twice the storage for the number.

Size : 8 bytesRange : 3.4 * 10-4932 to 3.4 * 104932 -1

5. void data type :

It specifies the empty set of values.

It is used for the functions that doesn't return value.


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` The data types explained above have the followingmodifiers.

1. short

2. long

3. signed

4. unsigned

` The modifiers define the amount of storage allocated tothe variable. The amount of storage allocated is not cast instone. ANSI has the following rules:

o short int


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Types Size (in bytes) Range

short int 2 -32,768 -> +32,767

unsigned sh

ort int 2 0 -> +65,535unsigned int 4 0 -> +4,294,967,295

long int 4 -2,147,483,648 -> +2,147,483,647

signed int 2 same as int

signedchar 1 -128 -> +127

unsignedchar 1 0 -> +255float 4

double 8

long double 12


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` The Data types that are derived from the

fundamental data types.

` The types of derived data types are:

1. Arrays

2. Functions

3. Pointers

4. References

5. Constants


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` Arrays are used in C to represent structures of

consecutive elements of the same type. The definition

of a (fixed-size) array has the following syntax:

int array[100];

which defines an array named array to hold 100

values of theprimitive type int.

` If declared within a function, the array dimension may

also be a non-constant expression, in which case

memory for the specified number of elements will be

allocated.


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` A function is a named part of a program that can be invoked fromother parts of the programs as often needed.

` Syntax of function:

type fuction-name(parameter list)

{.

body of function

}

` A function must have a return statement.

` A function can be invoked by two manners:

1.Call by value: It copies the values of actual parameters and

creates its own copy of arguments and uses them.2.Call by reference : It doesnt create a copy and directly refers

to the original parameters only different name i.e references.


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` In declarations , the asterisk modifier (*) specifies apointer type.

` For example, where the specifier int would refer to theinteger type, the specifier int * refers to the type

"pointer to integer".` The following line of code declares a pointer-to-integer

variable called ptr:

int *ptr;

` Pointer values associate two pieces of information:1. Memory address

2. Data type


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` A reference is an alternative name for a object.

` A reference variable provides an alias for a previously

defined variable.

` Its declaration consist of a

base type, an

&

(ampersand) and a reference variable name.

` In the following example, ptr is set so that it points to

the data associated with the variable a:

int *ptr;

int a;

ptr = &a;


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` The keyword const can be added to the

declaration of an object to make that object a

constant rather than a variable.

` The value of the named constant cannot bealtered during program run.

` Syntax:

const type name = value;

` So it must be initialized at the time of declaration.


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` The UserDefined data types are that derived data

types which are defined by the user

` The types of user defined derived data types are :

1. structure

2. union

3. enumeration


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` A structure is a variables referenced under one name,providing a convinient means of keeping related informantiontogether.

` The variables that make up structure are called structureelements.

` Keyword struct is used to construct a structure.

` Syntax :

struct name{

structure elements;

};` A structure is diff. from an array as, array is the collection of

similar data types where as structure is collection of diff. datatypes.


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` Unions in C are related to structures and are defined

as objects that may hold (at different times) objects of

different types and sizes.

` They are analogous to variant records in other.

` Unlike structures, the components of a union all refer

to the same location in memory programming

languages.

` The size of a union is equal to the size of its largest

component type.

` Keyword union is used to declare and create a union.


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` Used to create a group of values which are named constants in C,

C++, C#, Java, etc.

` Examples in C/C++/C#:

enum days {Mon, Tue, Wed, Thu, Fri, Sat, Sun}; //Mon = 0, Tues = 1, .

. ., etc.

days today, yesterday = Wed;

today = yesterday + 1;

` The first constant in an enumeration is assigned the value zero, and

each subsequent value is incremented by one over the previous

constant.

` Specific values may also be assigned to constants in the

declaration, and any subsequent constants without specific values

will be given incremented values from that point onward.


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` The reason for providing so many data types is to

allow programmer to take advantage of hardware

characteristics.

` Helps in avoiding wastage in memory.

` Helps in avoiding wastege of time.


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Different Data Types in ‘C’