Fundamental structure

of programming in 'c'

Presented by:

Mr. Yogesh KumarM.Sc. I Sem.(Bioinformatics)

‘C’ language is simple as compare to the English language

Here is steps comparison…Steps in learning English language

Steps in learning ‘c’

Getting started with 'c'

alphabets words sentences

paragraph

Alphabets , digits

Special symbols

Constants,

variableskeywords

instructions

program

Before planning a program we need to define its logic

(the correct sequence of instructions need to solve the

problem at hand).the term algorithm is often used to refer to the logic of a program.

It is a step by step description of how to arrive at the solution of the given problem.(exp..)

*Write a program to find the larger of two given numbers.Algorithm.1.Input two numbers a and b2.Assign big=a3. If (b>big)the big=b4.Output big5.stop

Concept of Algorithm

Flowchart is the diagrammatic representation of programs and algorithm . it is generally used to understand the program and to solve the program

It uses boxes of different shapes to denote different types of instructions.

The process of drawing a flowchart for an algorithm is often referred to flowcharting

Concept of flowchart

Only a few symbols are needed to indicate the necessary operations in a flowchart. These basic flowchart symbols have been standardized by the American National standards institute (ANSI).

As shown……

flow lines

connector

Basic flowchart symbols

start processing Input/output

decision

example.1

no yes

Flowchar to print first 10 multiple of a given natural numbers using while

start

Read num

i=1

Isi<=1

0

Write(i*num)

i=i+1

stop

Tokens in ‘c’

The alphabets ,numbers and special symbols when properly combined form constants , variables & keywords

Alphabets A,B,C………..Z a , b, c ……....z Digits 0,1,2,3……….9Special symbols ~, ’, !, @, #, %, ^, &, =,|,?,

/,

[ ] : ; ””,’ <> ., { }

constant’s , variable’s & keyword’sConstant, variables & keywords

Variables and constant in ‘c’.constant is an entity that doesn’t change x

x =3

x x=5 we can’t change 3&5 so it is called constant Here at one memory location we can store one value ,we can’t over write it as against this 3&5 do not change , hence are known as constant

3

5

PRIMARY CONSTANT

Integer constantReal constantCharacter

constant

ArrayPointerStructureUnionEnum.etc

Types of c constants1.Primary constant 2.Secondary constant

SECONDARY CONSTANT

As we saw earlier , an entity that may vary during program execution is called a variable.

Type of variable used in program depend on the type of constant stored in it.

Float/real, integer ,or character constantVariable name are name given to locations in

memory

Exp….float=6.0 (4 byte)Int =6 (2 byte)char=‘a’ (1 byte)

Types of c variables

Keywords are the words whose meaning has

already been explained to the c compiler The keywords cannot be used as variable name if

we do so, we are typing to assign new value to keywords which is not allowed by compiler

There are 32 keywords available in cSome are …….short return double switch register signedlong void float union static unsignedint break if goto continue volatilechar default for do sizeof enum else case while auto extern typedef

..etc

C keywords

• structure•class

• integer• float •Character (char)

•int %d •float %f•char %c

•Array•Pointer•Function•String

DATA TYPES

User define data type Fundamental data type Derived data type

'C' operators

Arithmetic operators

+ - * / %

purpose

AdditionSubtractionMultiplication

DivisionRemainder after division

example

7+5=12 7-5=27*5=35

8/2=47%5=2

ARITHMETIC OPERATORS

&& Means logical AND

|| Means logical OR

! Means logical NOT

LOGICAL OPERATOR

RELATIONAL OPERATORS

> Means greater than

< Means less than

== Means equal to

>= Means greater than equal to

<= Means less than equal to

!= Means not equals to

‘C’ has two most useful operators Increment operator ++ ,(m++)or m=m+1

Decrement operator -- ,(m--) or m=m-1 1. m++ simply increase the value by 12. m– -simply decrease the value by 1

Conditional operatorA ternary operator “?” is used in c to construct conditional

expression of the form

Expression1 ? Expression2 : expression3;

Increment and decrement operators

Example of conditional operator #include<stdio.h> #include<conio.h> void main() { float x,y,big; printf("enter the two values\n"); scanf("%f%f",&x,&y); big=(x>y? x:y); printf("the largest number is %f\n",big); } Run Enter the two number 12 45.70 the largest number is 45.70

TYPES OF PROGRAMMING IN 'C'

Decision statements1. if statement2. if else statement3. switch statement Repetitive statements:1. while loop2. do while3. for loop

Decesion making and branching

If statement (DECESSION

STATEMENT)

The general form of if statement is

if ( condition) { Statement-block }

If condition is true the statement block will executed otherwise the statement block will skipped.

#include<stdio.h>#include<conio.h>void main(){float a,b,big;printf(“enter two numbers\n”);scanf(“%f%f”,&a,&b);big=a;if(b>big) big=b;printf(“larger number is:%f”,big);}

RUNEnter two numbers12.5 45.0Larger number is 45.0

if statement example

ENTER

false

true

next statement

condition

Statement-block

if (condition) { statement-1; } else { statement-2; }

if .....else statement

enter

false true

next statement

Condition?

Statement-1Statement-2

The switch statement test the value of given expression against a list of case values

General form switch(expression)

{

case val-1:

statement-1

break;

case val-2:

statement-2;

break;

default:

default-statement;

break;

switch statement

#include<stdio.h>#include<conio.h>void main(){char grade;switch(grade){case ‘A’:printf(“passed with first division”);break;case ‘B’:printf(“passed with second division”);break;case ‘C’:printf(“conditional pass”;break;default:printf(“fail”);break;}getch();}

Example of switch statement

There are two types of repetitive structures

1. Conditional controlled (in this body is repetitively executed until the given condition become true)

a) while statementb) do while statement

2. Counter controlled (in this the number of time

the set of statement is executed ex.. )For loopa) while statement while(condition)

{

Statement(s);

}

Repetitive structures

1. evaluate the condition.2. If the condition true then execute the statement(s)and repeat step 1.3. If the condition is false then the control is transferred out of loop.Exp…..#include<stdio.h>main(){ int num=1,s=0; While(num<=10){ sum +=num; num+1=1;} printf(“sum of first 10 natural numbers : %d ”, s); getch();} RUN Sum of first 10 natural num is : 55

The sequence of operation in while loop

no yes

Flowchar to print first 10 multiple of a given natural numbers using while

start

Read num

i=1

Isi<=1

0

Write(i*num)

i=i+1

stop

In while statement, condition is evaluated first. Therefore the body of loop may not be executed at all if condition is not satisfied at the very first attempt. But in do loop, condition is evaluated at the end. Therefore the body of the loop is executed at lest once in this statement

The general form of this statement is.. do { Statement(s); } while (condition); printf(“…………….”); }

Do while statement

#include<stdio.> main( ) { int num=1,s=0; do { s +=num; num +=1; } while(num<=10); printf(“sum of first natural no is %d”,s) ; getch(); }Run:Sum of 10 natural number is 55.

(do while )..exp..sum of first 10 natural number

• The difference b/w. while & do while loopI. In while the condition is tested before

executing body of loop. /In do while the condition is tested after executing the body

II. Body of do loop is executed at lest once but body of while loop may not be executed at all. /In while , If initial the condition is not satisfied the loop will to get executed even once

While loop verses Do loop

There are situation where you want to have a statement or group of statements to be executed numbers of time and the number of repetition does not depend on the condition but it is simply a repetition up to a certain numbers. The best way of repetition is a for loop. The general form of the loop for single statement is:

for ( initialization ; condition ; increment) { statement(s); }

The for loop statement

#include<stdio.h> main( ) { int I,s=0; for (i=1;1<=10;i++) s=s+1; printf(“sum of first natural number

is:%d”,s); getch( ); } Run:Sum of first 10 natural number is : 55

For loop example to print 10 natural number

Loop construct can be nested or embedded within one another. The inner loop must be completely embedded with the outer loop . There should no overlapping of loops.

**Demonstration of nested loops** #include<stdio.h>

void main()

{

int r,c,sum; for (r=1;r<=3;r++) /*outer loop*/

{

for(c=1;c<=2;c++) /*inner loop*/

{

sum=r+c;

printf(“r=%d c=%d sum=%d\n”,r,c,sum);

}}

getch();

}

Output

r=1 c=1 sum=2

r=1 c=2 sum=3

r=2 c=1 sum=3

r=2 c=2 sum=4

Nested for loop

The loop that we have used so far executed the statements within them a finite number of times. However, in real life programming, one comes across a situation when it is not known beforehand how many times the statements in the loop are to be executed. This situation can be programmed as shown below:

/* execution of a loop an unknown number of times*/#include<stdio.h>

void main()

{

Char another;

Int num;

do

{

printf(“enter a number”);

scanf(“%d”,&num);

printf(“square of%d is %d”, num, num*num);

Printf(“\n want to enter another number y/n”);

Scanf(“%c”,&another);

}while(another==‘y’);

}

getch();

}

Output

Enter a number 5

Square of 5 is 25

Want to enter another number y/n y

Enter a number 7

Square of 7 is 49

Want to enter anotehr number y/n n

Odd loop

THANK YOU ……. .