Chapter 3 IFTHENELSE Control Structure © 2008 Pearson Education Inc., Upper Saddle River, NJ. All rights reserved. Marilyn Bohl/Maria Rynn Tools for Structured and Object-Oriented Design, 7e

Introduction In a SIMPLE SEQUENCE the steps are carried out in a sequential manner.  It may be desirable to vary the sequence of processing steps carried out within a solution algorithm.

Billing Problem (Flowchart)‏

Billing Example Decision symbol  The diamond-shaped symbol.  A choice between two alternative paths, or sequences of instructions, is made.

Pseudocode  Similar to some high-level programming languages, but it does not require that we follow strict rules as we would if actually writing a program.

Pseudocode—Introduction

IFTHENELSE Control Structure IFTHENELSE control structure  A small, circular symbol, called a connector symbol, is used to represent the decision-making logic within the IFTHENELSE pattern

IFTHENELSE--Generic

Time Card Problem

Time Card Example No-function condition—null ELSE  The no-function condition is represented by enclosing the key-word ELSE in parentheses.

Sample Problem 3.1 Payroll Problem  Compute the pay for an employee.  Regular pay will be computed as hours (through 40) times rate.  Overtime pay (1.5 times hours times rate) for all hours worked over 40.

Payroll Problem (Flowchart)‏

Payroll Problem (Flowchart) cont.

Payroll Problem (Pseudocode)‏

Finding the Smallest Number (Flowchart)‏

Finding the Smallest Number (Pseudocode)‏

Sample Problem 3.3 Bank Problem  Compute the new balance in a customer's bank account. A deposit (code of 1) or withdrawal (code of 2)‏

Bank Problem (Flowchart)‏

Bank Problem (Flowchart) cont.

Bank Problem (Pseudocode)‏

Character-String Constant The following information would be output as a result of 3 being input and the WRITE statement:  Designate character-string by enclosing it in single or double quotation marks, distinguishing it from a variable name.  If we included the variable name CODE within the quotation marks:

Character-String Constant  Assign the value of a character-string constant to a variable by means of a statement.  Use a character-string constant in a decision statement.  Compared to the letter D.  Compared to the value of the variable D.

Sample Problem 3.4 Sales Problem  The commission rate is based on two factors, the amount of sales and the class to which the sales person belongs.

Sample Problem 3.4

Sales Problem (Flowchart)‏

Sales Problem (Pseudocode)‏

Sales Problem (Pseudocode) cont.

Sales Problem (Visual Basic— Screen 2)‏

Sales Problem (Visual Basic— Screen 3)‏

Enrichment If the user clicked the Compute Commission a message box will display information to the user.

Sales Problem (Visual Basic— Screen 4)‏

Sales Problem (Visual Basic— btnCompute_Click)‏

Sales Problem (Visual Basic— btnCompute_Click) cont.

Sales Problem (Visual Basic— btnEnd_Click)‏