CHAPTER 1 PSEUDOCODE & FLOWCHARTS 1 st Semester 1433-1434 H King Saud University College Of Applied Studies and Community Services CSC 1101 Computer Programming-1.

CHAPTER 1PSEUDOCODE & FLOWCHARTS

1st Semester 1433-1434 H

King Saud University College Of Applied Studies and Community Services CSC 1101Computer Programming-1Done By: Asmal AlosaimiEdited By: Noor Alhareqi & Alaa Altheneyan

Levels of Program Development

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1. Define the problem. Human thought

2. Plan the problem solution. writing the algorithm [pseudo-natural language (English, Arabic) or drawing the flowchart diagram).

3. Code the program. High Level Programming Language (C, C++, Java, …)

4. Compile the program. Machine Code

5. Run the program.6. Test and debug the program.

From Lec1 we learn that

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When planning for a problem solution, algorithms are used to outline the solution steps using English like statements, called pseudocode.

or A flowchart , which is a graphical

representation of an algorithm.

Pseudocode

Pseudocode is a detailed description of what a computer program must do, expressed in an English like language rather than in a programming language.

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Pseudocode Example

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Write a Program to Print the Sum of two integer Numbers

1. Start the program2. Read the first number and save in the variable

( N1 )3. Read the second number and save in the

variable ( N2 )4. Sum the both numbers and save the result in

the variable ( Sum ) Sum = N1 + N2 5. Print the variable ( Sum ) 6. End the program

Flowchart

A flowchart is a type of diagram that represents an algorithm , showing the steps as boxes of various kinds [ex: rectangles, diamonds, ovals], and their order by connecting these with arrows. 

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Flowcharts Symbols

7Start/End

Read/Print

Arithmetic Operations

Decision , can be used with loops

Start

Read n1

N2 = 5

End

Print n1

N2 = n1+3

n1 > 3

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Draw a flowchart for a program that calculates

and print the area and the perimeter of a rectangle. Input

Length width

Processing Area = length*width Perimeter = 2*( length + width)

Output Area Perimeter

start

Read L, W

perimeter = 2 (L+W)

Print area

End

area = L * W

Print perimeter

Solution

Example 2

Draw the flow chart for a program that calculates the total salary for an employee using this equation:

Total_Sal = Salary +Overtime

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start

Read Salary

Print Total_Sal

End

Total_Sal = Salary +Overtime

Solution

Input Salary Overtime

Processing Total_Sal = Salary +Overtime

Output Total_Sal

Read Overtime

Example 3

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Draw a flowchart for a program that calculates and prints the sum of the even integers from 2 to 30.

Input No input.

Processing Sum = 2+4+6+8+……+28+30.

Output sum

Solution

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Pesudocode: Start the program Create a variable to hold a counter from 2 to 30. Initialize the counter to 2. Create a variable to hold the sum. Initialize the sum to zero. Loop While the counter is less-than-or-equal to 30

add the counter to the sum add two to the counter.

repeat until the counter reach 30 Print the sum. End of program

Solution

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StartStart

EndEnd

Counter=2, Sum=0 Counter=2, Sum=0

Counter≤30Counter≤30

Sum= Sum + CounterSum= Sum + Counter

Counter=Counter+2Counter=Counter+2

Print SumPrint Sum

yesyesnono

yesyes

Example 4

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Draw a flowchart for a program that determine if the temperature degree is above or below freezing.

Input Temp.

Processing Check if Temp is below the 32 below freezing. Check if Temp is above the 32 above freezing.

Output

Print “below freezing” or “above freezing”

Solution

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Example 5

Draw a flowchart for a program that accepts a person’s initial bank balance followed by a sequence of numbers representing transactions. A positive number represents a credit entry in the account and a negative number represents a debit entry. The input is terminated by a zero entry. The program should print the new balance.

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Solution

Input bank balance. transactions

Processing balance = balance + transaction.

Output balance

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Solution

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StartStart

EndEnd

Transaction !=0Transaction !=0

Print balance Print balance

yesyesnono

Read balanceRead balance

balance =balance + transactionbalance =balance + transaction

Read transactionRead transaction

Example 6

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Draw a flowchart for a program that calculates the Zakat, where the user enter the amount of money then the program show the zakat.

Zakat =(2.5/100) * amount. Zakat is not calculated if the amount is less

than 1000 S.R

Solution

Input amount.

Processing Check if amount is below 1000 Zakat =0. Check if amount is above 1000 Zakat

=(2.5/100) * amount Output

Zakat

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Solution

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StartStart

EndEnd

Amount > 1000Amount > 1000

Zakat =0.Zakat =0.

Print ZakatPrint Zakat

yesyesnono

Read amountRead amount

Zakat =(2.5/100)*amountZakat =(2.5/100)*amount