Data Types Presentation 1

8/2/2019 Data Types Presentation 1

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Enge:SajidaIntroduction to computing

Identifier

The identifiers are the names used torepresent variable ,constants, types

functions in the program

Types of identifiers

Standard identifiers

User defined identifiers


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Standard identifier

A type of identifier that has the special meaning

in the c++

cout and cin are example of standard identifiers

User-defined IdentifierThe type of Identifier that is defined by the

Programmer to access memory location known

as user-defined Identifier.


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The user-defined identifiers are used to store

data and program results.

Some examples of user-defined identifiers are,

marks and age etc.


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Keywords

Keywords is a word in C++ language that has a

predefined and purpose.

The meaning and purpose of a keyword is

defined by the developer of the language.

It can not be changed or redefined by user.

Keyword can be used for the same purpose for

which it is defined.

Keyword can be used for the same purpose for

which it is defined.


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Keywords are also known as reserved words.

These are different types of keywords in C++

language.

The total number of keywords is 63.

Char, do, If struct float


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Data types

Data type defines a set of values and a set of operations

of those values

The data is given to the program as input

The data is processed according to the program

instruction and output is returned

A C++ program may need to process different types of

data

Each data type require different amount of memory


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Types of data type

Integer data typeFloat data type

Double data type

Char data type


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Integer data type

A numeric value that has no decimal point or fraction

It includes both positive and negative valueTypes of integers

C++ provides different types of integer data

Int

Short intLong int

Unsigned int

Unsigned long int


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Int data type

Is used to store integer values

It takes two or four bytes in memoryIt takes two bytes and its range is from -32768 to 32767

Unsigned int data type

Is used to store the positive integer values

It takes two bytes in memoryIts range is from 0 to 65,535


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Unsigned long integer data type

Is used to store positive integer values

It takes four bytes in memory its range is from 0 to4,294967295

Long integer data type

Long integer data type is used to store large integer

valueIt takes 4 bytes in memory

Its range is from2,147,483648 to 2,147,483,647

Short int data type

Is used to store integer value

It takes two bytes in memory

Its range is from o to 65,535


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Real data type

Real data type is numeric value with decimal point or

fraction

It is also called floating point number

It includes both positive number and negative number

Example are 10.5,-10.91

Types

Float

Long float

Double

long double


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Float data type

Float data type is used to store real values

It takes four bytes in memoryIts range is from 3.4*1038 to 3.4*10-38

Double data type

Double data type is used to store large real values

It takes 8 bytes in memory

Its range is from 1.7*10-308 to 1.7*10308

It provides accuracy of 15 decimal places


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Long double data type

Long double data type is used to store very large

real values

It takes 10 bytes in memory

its range is from 1.7*10-4932 to 1.7*10 4932

it provides accuracy of 19 decimal places


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Character data type

Char data type is used to store char value

It takes one byte in memoryIt is used to represent a letter, number, or punctuation mark and a

few other symbols

Character values is normally given in single quotes

It can represent individually characters such as a,x,5

Character 5 is treated differently than integer 5

The key word signed and unsigned can be used char data type

The signed character can represent number from 127 to -128

The unsigned characters can represent number from 0 to 255


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Integer over flow and under flow

Integer overflow occurs when the value assignedto an integer variable is more than its

maximum possible value

Integer underflow occurs when the value is

assigned to an integer is less than possible

minimum value


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Variables

A variable is a named memory location or memory cell

It is used to store programs input data and itscomputational results during execution

The value of a variable is changed during the executionof program

The value stored in a variable is referred by variable

nameThe variables are created in RAM

Data stored in variable is temporary

It can be used and processed during the execution of theprogram

The data stored in the variables is automaticallyremoved when program ends


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The value of a variable is changed during

program execution but its name will remain

same

Marks

10

Name of variable

Location of variable

Computer memory


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Variables declaration

The process of specifying the variable name and its typeis called variable declaration

All variable must be declared before they are used in theprogram

Compiler uses the declaration to determine how muchmemory is needed for each variable

Different type of variables require different amount ofmemory

The required number of bytes are allocated when avariable is declared


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Syntax

The syntax of declaring variable is as follows

Data- type variable-name ;Data type it indicates type of data that can be stored in

variable

Variable name refers to memory location of the variable

Int marks;

float avg;

Double salary;


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Variable initialization

The process of assigning a value to a variable at the time ofdeclaration

The equal sign is used to initialize a variableSyntax

Typename variable = value ;

Type name indicates the data type of the variable to be initialized

Variable name of the variable to be initialized= assignment operator

Value it is the value to initialize a variable

Int n =100;


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Constant

Constant is the quantity that cannot be change duringthe program execution

Types

Literal constant

Symbolic constant

Literal constant is a value that is typed directly in theprogram

It appears in the program where it is needed

Hello world is string literal constant


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Types of literal constants

Integer constantFloating point constant

Character constant

String constant


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Symbolic constant

A symbolic constant is a name given to the values that

can no be changed

Symbolic constants are used to represent a value that is

frequently used in the program

Types of symbolic constantConst qualifier

Define Directive


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Const Qualifier

Const qualifier is used to define a constant

Const is declared by its name and its data type

The const must be initialized with some value theinitialized value can not be changed during the

program executionSyntax

Const data type identifier=value;

Const int N=100;


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Define directive

Also used to define a constant

It does not specify the data type of the constant

Define directive starts with # symbol

It is not terminated with semicolon

Syntax

#define identifier value

# starts of preprocessor directive

Define used to define a constant

Identifier it is the name of constant

Value it represents the value associated with theidentifier

#define PI3.141593

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Data Types Presentation 1

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