Basic of c &c++ (Rohan Khanna's Conflicted Copy 2012-05-23)

7/31/2019 Basic of c &c++ (Rohan Khanna's Conflicted Copy 2012-05-23)

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C++ Data Types

Built-In Type

Integral type - int, char

Floating typefloat, double

Void

Used to specify the return type of a function

when it is not returning any value

To indicate an empty argument list to a

function. Example : void fun (void);


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C++ Data Types

Used in declaration of generic pointers. Void *gp;

A generic pointer can be assigned a pointer

value of any basic data type, but it may not

be dereferenced.

For ex: int * ip; gp = ip; // assigns int

pointer to void pointer.

But, *ip = *gp; is illegal;It would not make sense to dereference a pointer

to a void value.

LOOPS


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C++ Data Types

User-defined type

1. Structure

2. Union3. Class

4. Enumeration


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C++ Data Types

Structure and Union in C.

They are used in C++ with some added

features of object oriented languages.

Class is used in c++.

The class variables are known as objects.


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Enumerated Data type

It is user defined data type which provides a

way for attaching names to numbers.

It increases the comprehensibility of the

code.

The enum keyword automatically

enumerates a list of words by assigning themvalues 0,1,2 and so on.

It is used to create symbolic constants.


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The enum statement is similar to the structstatement.

Ex : enum shape {circle, square, triangle}

enum color{ red, blue, green, yellow}

They differ from enum in C .

In C++, they can be used as new type names.

By using, tag names we can declare new

variables.

shape ellipse; // ellipse is of type shape.


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ANSI C defines the types of enums to be ints. In c++, each enumerated data type retain its

own separate type.

C++ does not permit an int value to beautomatically converted to an enum value.

Ex : color background = blue; // allowed

color background = 7; // error in c++ color background = (color) 7; // ok


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An enumerated value can be used in placeof an int value.

Ex : int c = red; // valid, color type

promoted to int By default, enumerators are assigned

integer values starting from 0. We can

override these values by :enum color {red= 8, blue = 4, green};


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C++ also permits the creation of anonymous

enums ( enums with out tag names)

Ex : enum {off, on};

int switch_1 = off;


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Derived data types

Array : contiguous/ continuous memory space.

Character arrays are initialized in different

way:

Ex in C :char string[3] = xyz // programmer

intends to leave out the null character \0.

Ex in C++ : char string[4] = XYZ


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Derived data types

Function: A block of code that is to beexecuted to serve some purpose.

Pointers:

int * ip; // int pointer

ip = &x; // address of x assigned to p;

*ip = 10; // 10 assigned to x through

indirection.


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Difference Between The Two?

Constant pointer

Pointer to a constant


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Constants

Constants refer to fixed values that do notchange during the execution of a program.

They include integers, characters, floating

point numbers and strings.Literal constant do not have memory locations.

Examples:

123 // decimal integer

12.34 // floating point integer

037 // Octal integer


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Constants

0x2 //hexadecimal integer C++ //string constant

A // character constant

Lab // wide-character constant wchar-_t type is a wide-character literal

introduced by ANSI C++ and is used for character

sets that cannot fit a character into a single byte.

Wide-character literals begin with the letter L.


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Symbolic constants

They can be created as follows:

1. Using the qualifier const, and

2. Defining a set of integer constants using enum

keyword.

Any value declared as const cannot be modifiedby the program in any way.

ex : Const int size = 10;

C++ requires a constant to be initialized. ANSI C does not require an initialization, it will

give a default value 0.


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Symbolic constants

Enumeration example :enum { x, y, z};

const x = 0;

const y = 1;

const z =2;

Or explicitly, enum {x=100, y = 50,z=200};


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Control Structures

Three control structures: Sequence structure ( straight line)

Selection structure (branching)

Loop structure ( iteration or repetition)


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Selection structure (branching)

Simple If statement

if (condition){ // code

}

Ifelse statementIf (condition)

{

// code}

Else

{// code}


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Switch statement

This is multiple branching statement, basedon a condition.

The control is transferred to one of themany possible points.

Syntax:

switch (expression)

{

case 1:

{ //code

}


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Switch statement

case 2:{ //code

}

Default:

{// code

}

}


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LOOPS

Do While :exit controlled loopDo

{

// code

}while (condition is true);


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LOOPS

While Loop : entry controlled loop

while (condition is true)

{ // code

} For Loop : entry controlled and action will

repeated a predetermined no. of times

for( initial value; test; increment)

{ // code

}

Basic of c &c++ (Rohan Khanna's Conflicted Copy 2012-05-23)

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