Loops Control Structure - WordPress.com€¦ · Loops Control Structure Rab Nawaz Jadoon Assistant Professor COMSATS IIT, Abbottabad ... Loops The programs that we have developed

Department of Computer Science

DCS

COMSATS Institute of Information Technology

Loops Control Structure

Rab Nawaz JadoonAssistant Professor

COMSATS IIT, Abbottabad

Pakistan

Introduction to Computer Programming (ICP)


Loops

The programs that we have developed so far used either a sequential or a decision control instruction.

In the first one, the calculations were carried out in a fixed order.

While in the second, an appropriate set of instructions were executed depending upon the outcome of the condition being tested (or a logical decision being taken).

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Department of Computer Science 3


Loops

The versatility of the computer lies in its ability to perform a set of instructions repeatedly.

This repetition operation is done through loop structure.

There are three structure through which we can repeat the part of a program.

While loop

For loop

Do while loop

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The while loop

The while loop continues to loop while some condition is true.

When the condition becomes false, the looping is discontinued.

The general from of while loop is,

initialize loop counter ;

while(test loop counter using a condition)

{

do this;

and this;

increment loop counter ;

}

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Flow chart of while loop

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Important points

In place of the condition there can be any other valid expression.

So long as the expression evaluates to a non-zero value the statements within the loop would get executed.

The condition being tested may use relational or logical operators as shown in the following examples:

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The while loop

The statements with in the loop may be one or multiple. Braces are optional, for example,

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The while loop

As a rule the while must test a condition that will eventually become false, otherwise the loop would be executed forever, indefinitely.

This is an indefinite loop since i=1 remains forever.

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The while loop

The correct form would be as under,

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The while loop

Instead of incrementing, we can decrement the counter as well, for example,

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The while loop

It is not necessary that a loop counter must only be an int. it can be even float.

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More operators

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Problem statement 1

A class of ten students took a quiz. The grades (integers in the range 0 to 100) for this quiz are available to you. Determine the class average on the quiz.

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?5min


Solution

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Problem statement 2

Find out the factorial of a given number using while loop???

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?5min


Solution

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Output !!!

Enter a number. 5Factorial= 120


Problem statement 3

Find the sum of all the digits from 1 to given number???

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?5min


Solution

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Output !!!

Enter a number. 5Sum = 15


Problem statement 4

Write a program that find the even upto a given number and add all the those even numbers?

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?5min


Solution

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Output !!!

Enter a number. 100246810

Sum of all the even from 1 to 10 is 30


Problem statement 5

Generate the following output using while loop? (table of 2)

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Output !!!

Enter a number. 161 x 2 = 22 x 2 = 43 x 2 = 64 x 2 = 85 x 2 = 106 x 2 = 127 x 2 = 148 x 2 = 169 x 2 = 1810 x 2 = 2011 x 2 = 2212 x 2 = 2413 x 2 = 2614 x 2 = 2815 x 2 = 3016 x 2 = 32

?2min


Solution

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Problem statement 6

Write a program that print ASCII 8 table against the (letters, number, symbols etc) using while loop???

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?2min


Solution

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Analyze the output???

Department of Computer Science 26

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Loops Control Structure - WordPress.com€¦ · Loops Control Structure Rab Nawaz Jadoon Assistant Professor COMSATS IIT, Abbottabad ... Loops The programs that we have developed