Post on 05-Jan-2016
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