C Programming - Decision & Loop

Control

Organized By: Vinay Arora

Assistant Professor, CSED

Thapar University, Patiala

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Decision Control

� The if statement

� The if-else statement

� The conditional operators

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Forms of if

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Forms of if (contd.)

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Relational Operator

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Demonstrating - If

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Flowchart

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Demonstrating - If

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Flowchart

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Expression in Conditional Part

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Multiple statements within if

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Demonstrating If - Else

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Flowchart If-Else

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Logical Operators with If-Else

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Logical Operators with If-Else

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Else-if ladder

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Logical Operators with If-Else

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Smallest amongst 3 nos.

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Smallest amongst 3 nos.

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Program using Logical OR, elseif

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Calculate Salary as per following table

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&& - Logical AND

� C allows usage of three logical operators, namely, &&, || and !

� These are to be read as ‘AND’ ‘OR’ and ‘NOT’ respectively.

� Don’t use the single symbol | and &. These single symbols also have a

meaning.

� The first two operators, && and ||, allow two or more conditions to be

combined in an if statement.

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&& - Logical AND (C Program)

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| | - Logical OR (C Program)

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! - Logical NOT

� This operator reverses the result of the expression it operates on.

� For example, if the expression evaluates to a non-zero value, then

applying ! operator to it results into a 0.

� Vice versa, if the expression evaluates to zero then on applying !

operator to it makes it 1, a non-zero value.

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! - Logical NOT (C Program)

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&&, ||, ! Operator

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? : - Conditional Operator

� The conditional operators ? and : are sometimes called Ternary

Operators since they take three arguments.

� They form a kind of foreshortened if-then-else.

� Their general form is, expression 1 ? expression 2 : expression 3

� If expression 1 is true (that is, if its value is non-zero), then the value

returned will be expression 2, otherwise the value returned will be

expression 3.

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Conditional Operator (C Program)

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goto Statement

� goto is used to switch the control flow.

� In a difficult programming situation it seems so easy to use a goto to

take the control.

� In most of the scenarios use of goto is depreciated.

� goto can be replaced by if-else, switch, for.

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goto Statement - Program

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switch Statement

� The control statement that allows us to make a decision from the number

of choices is called a switch.

The integer expression following the keyword switch is any C expression that

will yield an integer value.

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switch Statement - Flowchart

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switch Statement - Program

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Loops

� Repetitive instructions is done through a Loop control instruction.

� This involves repeating some portion of the program either a

specified number of times or until a particular condition is being

satisfied.

� There are three methods by way of which we can repeat a part of a

program. They are:

(a) Using a while statement

(b) Using a do-while statement

(c) Using a for statement

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while Loop - Flowchart

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while Loop – general form

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while Loop – forms of conditions

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while Loop – C Program

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While Loop – Program 1

//Program to demonstrate simple while loop

#include<stdio.h>

#include<conio.h>

void main()

{

int i=1;

clrscr();

while (i<=10)

{

printf("%d\n",i);

i=i+1;

}

getch();

}

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Output

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While Loop – Program 2

//Program to demonstrate simple while loop with decrement operator

#include<stdio.h>

#include<conio.h>

void main()

{

int i=5;

clrscr();

while (i>=1)

{

printf("%d\n",i);

i=i-1;

}

getch();

}

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Output

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While Loop – Program 3

/* Program to demonstrate simple while loop taking incremental value

as float */

#include<stdio.h>

#include<conio.h>

void main()

{

float i=10.0;

clrscr();

while (i<=10.5)

{

printf("\nCivil Engineering at Thapar");

i=i+.1;

}

getch();

}

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Output

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While Loop – Program 4

//Demonstrating simple while loop with integer value out of range

#include<stdio.h>

#include<conio.h>

void main()

{

int i=1;

clrscr();

while (i<=32767)

{

printf("%d\n",i);

i=i+1;

}

getch();

}

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Output – Infinite Loop

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While Loop – Program 5

//Program to demonstrate simple while loop

#include<stdio.h>

#include<conio.h>

void main()

{

int i=1;

clrscr();

while (i<=10);

{

printf("%d\n",i);

i=i+1;

}

getch();

}

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Output

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While Loop – Program 6

//Program to demonstrate post increment operator in while loop

#include<stdio.h>

#include<conio.h>

void main()

{

int i=1;

clrscr();

while (i<=10)

{

printf("%d\n",i);

i=i++;

}

getch();

}

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Output

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While Loop – Program 7

//Program to demonstrate compound assignment operator within while loop

#include<stdio.h>

#include<conio.h>

void main()

{

int i=1;

clrscr();

while (i<=5)

{

printf("%d\n",i);

i+=1;

}

getch();

}

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Output

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While Loop – Program 8

//Program to demonstrate post increment operator with while loop

#include<stdio.h>

#include<conio.h>

void main()

{

int i=0;

clrscr();

while (i++ < 5)

{

printf("%d\n",i);

}

getch();

}

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Output

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While Loop – Program 9

//Program to find out even numbers between 1-10

#include<stdio.h>

#include<conio.h>

void main()

{

int i=1;

clrscr();

while (i<=10)

{

if (i%2==0)

printf("%d\n",i);

i=i+1;

}

getch();

}

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Output

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Do-while Loop

WhileWhile

Do while

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Do-while Loop – Program 10

//Program to demonstrate DO-WHILE loop

#include<stdio.h>

#include<conio.h>

void main()

{

int i=1;

clrscr();

/*

while(i<1)

{

printf("hello i am at Thapar");

}

*/

do

{printf("hello i am at Thapar");

}

while(i<1);

getch();

}

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Output

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Program Transformation

Unary Post Increment

Operator

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Program Transformation

Compound

Assignment Operator

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For Loop

� The for allows us to specify three things about a loop in a single line:

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For Loop (Program-1)

//Program to demonstrate simple For loop

#include<stdio.h>

#include<conio.h>

void main()

{

int i;

clrscr();

for (i=1; i<=10; i=i+1)

printf("%d\n",i);

getch();

}

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For Loop (Program-1 Output)

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For Loop (Program-2)

//Program to demonstrate simple For loop

#include<stdio.h>

#include<conio.h>

void main()

{

int i;

clrscr();

for (i=1; i<=10;)

{

printf("%d\n",i);

i=i+1;

}

getch();

}

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For Loop (Program-2 Output)

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For Loop (Program-3)

//Program to demonstrate simple For loop

//Print numbers from 1 to 5

#include<stdio.h>

#include<conio.h>

void main()

{

int i=1;

clrscr();

for (;i<=5;i=i+1)

{

printf("%d\n",i);

}

getch();

}

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For Loop (Program-3 Output)

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For Loop (Program-4)

//Program to demonstrate simple For loop

#include<stdio.h>

#include<conio.h>

void main()

{

int i=1;

clrscr();

for (;i<=5;)

{

printf("%d\n",i);

i=i+1;

}

getch();

}

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For Loop (Program-4 Output)

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For Loop (Program-5)

//Program to demonstrate simple For loop

#include<stdio.h>

#include<conio.h>

void main()

{

int i;

clrscr();

for (i=0;i++<5;)

{

printf("%d\n",i);

}

getch();

}

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For Loop (Program-5 Output)

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For Loop (Program-6)

//Program to demonstrate simple For loop

#include<stdio.h>

#include<conio.h>

void main()

{

int i;

clrscr();

for (i=0;++i<5;)

{

printf("%d\n",i);

}

getch();

}

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For Loop (Program-6 Output)

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For Loop (Program-7)

//Program to demonstrate NESTED For loop#include<stdio.h>

#include<conio.h>

void main(){int i,j;

clrscr();

for (i=1;i<=5;i=i+1){printf("\n");

for (j=1;j<=i;j=j+1){printf(" *");}

}

getch();}

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For Loop (Program-7 Output)

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Thnx…