Lesson 5

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Algorithm Instructions Sequential Logic Structure Solution Development

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Terminal◦ Starts, Stops, Ends

Input/Output◦ Input data, Output information

Assign◦ Apply values to variables

Process◦ Execute instructions

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Terminal

Input/Output

Assign

Process

The oldest logic structure The most used logic structure The easiest structure to understand Is one statement after another statement,

after another statement, after another statement, etc.

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Enter Name Enter Address Enter City Enter State Enter Zip Enter Hours Enter Wage Pay = Hours * Wage

Print Name Print Address Print City Print State Print Zip Print Pay

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Elliott invests $5,000 in a savings account that yields 5% (.05) annual interest.

Assuming that all interest is left on deposit along with the original deposited amount◦ What will be the equation to calculate the

amount that will be in the account at the end of 10 years?

◦ How much will the interest be at the end of the 10 years?

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First: Research banking algorithms◦ We wind up with Two Equations:

First…the Tough one Amount = Principal * ((1 + Interest Rate) ^ Time)

Principal – amount to be invested Interest Rate – yearly percentage rate Time – investment period in years Amount – principal + interest earned

Next…the Easy one Interest = Amount – Principal

Interest – the actual amount of Interest

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Calculate Savings

Get input Calculate

PrintAmount

PrintInterest

CalculateInterest

CalculateAmount

Print

Get Principal Amount Get Yearly Interest Rate Get Time Intervals Calculate Amount of Principal + Interest

Amount = Principal * ((1 + Rate) ^ Time) Calculate Amount of Interest

Interest = Amount - Principal Print Amount of Ending Principal + Interest Print Amount of Interest

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In Visual Basic

Note: Up to this point it didn’t matter what language we use…

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Variable Name Data Type Module Defined Domain Scope

Principal Decimal GetInput

Calculate

0 < n < 1 million Global

InterestRate Double GetInput

Calculate

0 < n < 1 to 14+ digits

Global

Time Short GetInput

Calculate

0 < n < 32,767 Global

Amount Single Calculate

PrintResult

0 < n < 1 million Global

Interest Single Calculate

PrintResult

0 < n < 1 million Global

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' Input Values by UserDim Principal As DecimalDim InterestRate As DoubleDim Time As Short

' Output ValuesDim Amount As SingleDim Interest As Single

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Internal Documentation

taking the form of Comments

Private Sub cmdGetInput_Click()Principal = CDec(InputBox("In Dollar amount " & _

“ (5000)", "Please Enter Principal Amount"))

InterestRate = CDbl(InputBox(" Ex. 5% " & _ “ would be entered as .05", "Please " & _ “ Enter Annual Interest Rate"))

Time = CShort(InputBox("An Integer " & _ “ with no decimals", "Please Enter Length "

& _ “ of Time in Years"))

End Sub

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Private Sub cmdCalculate_Click()

' Calculates Principal + Interest over timeAmount = Principal * ((1 + InterestRate) ^ Time)

' Calculates amount of total Interest at end of' time period

Interest = Amount - Principal

End Sub

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Private Sub cmdPrintResult_Click() lstOutput.Items.Add(" The Amount of Principal + " & _

“Interest Paid on") lstOutput.Items.Add(" the Principal Amount of " & _ VB6.Format(Principal, "Currency") & " for ") lstOutput.Items.Add(Time & " years is") lstOutput.Items.Add(" " & _

VB6.Format(Amount, "Currency")) lstOutput.Items.Add(" and the Amount of Interest is") lstOutput.Items.Add(" " & _

VB6.Format(Interest, "Currency"))

End Sub

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1st step

2nd step

3rd step

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Internal Documentation◦ Takes the form of comments within the program◦ Helped by using Mnemonic terms

Creates self-documenting code External Documentation

◦ Takes the form of User Manuals Help Screens System Documentation

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Input Variables to be tested◦ Principal

any numeric value greater than 0

◦ InterestRate any numeric value greater than 0 and less than 1

◦ Time any integer greater than 0

Note: We didn’t do any Error checking in this problem.

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Output Variables◦ Would expect to see the Amount a positive

number greater than the Principal amount◦ Would expect to see the Interest greater than

zero.

Why are these statements important?

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Analyze the problem◦ Being able to restate the problem is one

indicator that you understand the problem Develop the structure chart Develop the algorithms Develop the data dictionary Develop the code Test the solution

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