Fundamentals of Computing and C Programming - Part 2

Presentation By Karthik Srini

Fundamentals of Computing and C ProgrammingUnit II - Basics of C language


Seminar IIBy Karthik Srini


Synopsis

1. Data Types

2. Type Conversion

3. Type Definition

4. Control Structures


Data TypesIn the C programming language, data types refer to an extensive system used for declaring variables or functions of different types. The type of a variable determines how much space it occupies in storage and how the bit pattern stored is interpreted. They are categorised as :

1. Basic Data Type

2. Enumerated Data Type

3. The void Type

4. Derived Data Type


Basic Data Types

The basic data types in C are :

1. Integer data type

2. Float data type

3. Character data type


Integer Data TypeThe integer data types are further classified as integers and characters.

Integers can be classified with respect to length and sign as,

• Unsigned Integer

• Signed Integer

• Long Integer

• Short Integer


Signed Integer & Unsigned Integer

The are normally identified by the sign in front of the integer value. An integer value without any sign is assumed to be positive. (i.e.) unsigned.

For example,

unsigned int num = 10 ; ( unsigned )

int num = -10 ; ( signed )


Long Integer

If a large integer value is to be stored in a variable, then long is prefixed before int while declaring the variable.

For example,

If you want to store a mobile number ( 10 digits ), you declare it as ,

long int mobile_number = 1234567891 ;


Short Integer

Short integer is normally used to reduce the size of the program, since short int occupies less memory space than int and long int .

For example,

short num = 11 ;


Float Data Type

Float data type is normally used to represent floating points ( or ) floating numbers, float is prefixed before the variable name.

For example,

float pi = 3.14 ;


Double Data Type

Double data type is used to represent larger floating numbers

For example,

double num = 43.66677 ;


Long Double Data Type

Long double data type is used to represent even larger ( or ) longer floating numbers.

For example,

long double num = 4167.7789056 ;


Character Data Type

It is usually used to represent characters. The variable name is prefixed by char . Must be enclosed within single quotes.

For example,

char alphabet = ‘ c ’ ;


Enumerated Data Types


Enumerated Data Types

Enumerated data types are user defined data types. They are predefined with a discrete set of values by the user.

For example,

enum month ( Jan , Feb , Mar , Apr , May , Jun , Jul , Aug , Sep , Oct , Nov , Dec ) ;

enum month first = Jan ;


Type DefinitionIt is an user defined data type similar to enumerated data types, the only difference is, in type definition it is not necessary to define the discrete set of values.

For example,

typedef int number ;

number num1 , num2 ;


The void Data Type

Void means null ( or ) nothing. It is normally prefixed before functions.

For now, this information is enough. You will learn in detail in the forthcoming chapters.


Derived Data Types


Derived Data TypesThey include,

(a) Pointer types,

(b) Array types,

(c) Structure types,

(d) Union types and

(e) Function types.


ArraysArrays are defined as the collection of variables having the same base type ( or ) data type. Arrays are further classified as :

1. Single Dimensional Array

2. Double Dimensional Array

They are normally declared as like other declarations, but the array index must be specified.

For example,

int num [5] ;


int num[5];

Memory allocation for

the above array. 0 1 2 3 4

100 34 76 56 89


Type Conversions


Type Conversion

Conversion of values of one data type into another data type is called Type conversion. It is classified as :

1. Implicit Type Conversion

2. Explicit Type Conversion


Implicit Type Conversion

These are done by the complier itself, without the knowledge of the programmer.

For example,

int b = 7 / 2 ; ( value of b will be 4 )


Explicit Type Conversion

This type of conversion are done by the user willingly.

For example,

int pi = (int) 3.4 ;


Functions


Functions

A function is a group of statements that together perform a task. Every C program has at least one function, which is main(), and all the most trivial programs can define additional functions. You can divide up your code into separate functions.


Function Prototype

In computer programming, a function prototype or function interface is a declaration of a function that specifies the function's name and type signature (parameter types, and return type), but omits the function body.

For example,

int add ( int a , int b )


Control Structures


Control Structures

Control structure decide the way of flow of control in a program. Based on some test conditions, the control of the program gets jumped from one point to the other. They can be further classified as :

1. Selection Statements

2. Looping Statements


Selection Statements

The control of the program gets jumped from one point to the other based on a test expression. They are classified as :

1. If else

2. Switch Case


Simple if Syntax

if ( condition )

{

action block ;

}


if else Syntaxif ( condition )

{

Action block 1 ;

}

else

{

Action block 2 ;

}


if , else if , else Syntaxif ( condition )

{

action block 1 ;

}

else if ( condition )

{

action block 2 ;

}

else

{

action block 3 ;

}


Switch Case Syntax switch ( condition )

{

case 1 :

action block1 ;

break ;

case 2 :

action block2 ;

break ;

default :

action block3 ;

}


Looping Structures


Looping Structures

Looping is a type of control structure in which a set of instructions is repeated again and again until the test condition evaluates to true.

There are two major types,

1. Entry controlled loop

2. Exit controlled loop


Entry controlled loopChecks whether the test expression evaluates to true, before the statements in the loop gets executed. If the test expression evaluates to false, the loop terminates.

These have two loops in major,

1. For loop

2. While Loop


For loopFor loop has fixed number of repetitions. It is an entry controlled loop. It consists of three main clauses namely,

1. Initialisation expression

2. Test Expression

3. Update Expression

A for loop can have multiple initialisation expressions and multiple update expressions but can have only one test expression.


for Loop Syntax

for ( initialisation exp ; test exp ; update exp )

{

action block ;

}


While loop

While loop does not have fixed number of iterations. It is an entry controlled loop.


while Loop Syntaxinitialisation expression ; ( if needed )

while ( condition )

{

action block ;

update expression ; ( if needed )

}


Exit Controlled Loop

Checks whether the test expression evaluates to true, after the statements in the loop gets executed. It gets executed at least once.

They have one loop in major,

1. Do While loop.


Do While Loop

It is an exit controlled loop. Gets executed at least once.


do while Loop Syntaxinitialisation expression ;

do

{

action block ;

update expression ;

}

while ( condition ) ;


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Fundamentals of Computing and C Programming - Part 2

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