Input, Process, Output
Chapter 1
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A Guide to Working with Visual Logic
Introduction
—  A computer program is a solution to a
problem
—  Most useful computer programs do at least 3
things:
Input
— input data
— process data
Process
— output resulting information
Output
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A Guide to Working with Visual Logic
Internet Shopping Cart System
INPUT
Customer ID
Mailing
address
Credit card
number
Product I
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A Guide to Working with Visual Logic
PROCESS
Connect to
Database
Determine
product cost
Calculate
sales tax
Bill
customer
OUTPUT
Print customer
receipt
Generate
shipping label
Generate
report for sales
dept.
Logic and Syntax
—  An algorithm is the blueprint for a computer program/
software
—  Tools for representing algorithms
—  Flowcharts
—  Pseudocode
—  Visual Logic is a visual tool combining graphics of flowcharts
and pseudocode-like syntax
—  Visual Logic animates or executes the algorithm
—  Visual Logic IS NOT a computer programming language
—  Once an algorithm is developed it must be coded in a
programming language to be used as a computer program
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A Guide to Working with Visual Logic
Simple Programming Formats
—  An output statement displays information (in a window/
console/file)
—  An input statement accepts data from the user and stores
that data into a variable
—  A variable is a storage location in computer memory that
can be accessed and changed in the program
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A Guide to Working with Visual Logic
Simple Programming Formats (contd)
—  A variable has a name (which does not change) and an
associate data value (which may change during the
execution) e.g. NAME is the name of a variable and its
data value is the string “Dave”
• The name of a variable is also called an
identifier. An identifier cannot have any
spaces in it, only letters, numbers and
underscore (_)
• Legal identifiers: NAME, num1,
interestRate, Num_1, Num_2
• Visual Logic is case insensitive
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A Guide to Working with Visual Logic
Hello Name Program
The input string value
MUST be entered
inside quotes (“ “)
But the output string is not
displayed with quotes (“ “)
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A Guide to Working with Visual Logic
Input Statement Summary
—  Input statements are used to get data into variables
—  In Visual Logic, the input flowchart element is a
parallelogram with the keyword Input following by the
variable name (e.g. Input: NAME)
—  When the input statement is executed the user is prompted
to enter a value using the keyboard. The value typed is then
stored in the variable for later use.
—  String input must be placed inside quotes
—  Numeric input must contain only digits and possibly one
decimal point. Percent symbols (%), dollar signs ($) and
commas (,) or any other symbols are not allowed.
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A Guide to Working with Visual Logic
Partial weekly paycheck solution
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A Guide to Working with Visual Logic
What’s this?
Assignment Statement
—  Assignment statements are used to perform calculations and
store the result
—  An assignment statement is a processing step, so its flowchart
shape is a rectangle
—  An assignment statement contains a variable on the left-hand
side (LHS), an expression on the right-hand side (RHS) and an
equal sign (=) in the middle
—  When an assignment statement is executed, the RHS
expression is evaluated first. This value is stored in the
variable (e.g. The result of the RHS becomes the data value of
the variable on the LHS)
—  Variables hold values and have a name—variables are named
memory locations
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A Guide to Working with Visual Logic
Weekly paycheck (partial solution)
Pay will have the value: ??
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A Guide to Working with Visual Logic
2030
Do you see the output?
Weekly paycheck (no formatting)
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A Guide to Working with Visual Logic
Weekly Paycheck (complete solution)
FormatCurrency is an intrinsic function
that formats the variable within the
parentheses with a $, a decimal point
and 2 places after the decimal
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A Guide to Working with Visual Logic
Note: the shape of
Output is different than
Input in Visual Logic
Weekly paycheck (no formatting)
What would you
see if you used
FormatCurrency?
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A Guide to Working with Visual Logic
Weekly paycheck (formatting)
FormatCurrency – rounds off to 2 decimal places
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A Guide to Working with Visual Logic
Arithmetic Expressions
—
—
—
—
—
4–5+2
1 + 3*7
52+2*8
12/4*2
12/5+3
Order of Operations:
PEMDAS
—  Parentheses
—  Exponents
—  Multiplication (*) &Division (/) (from left to right)
—  Addition (+) & Subtraction (-) (from left to right)
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A Guide to Working with Visual Logic
Operators in Visual Logic
OPERATOR
1.  Exponentiation
2.  Multiplication and Division
3.  Integer Division
4.  Integer Remainder
5.  Addition and Subtraction
SYMBOL
EXAMPLE
^
2^3 = 8
* , /
2*3=6, 5/2=2.5
\
5\2 = 2, 38\10= 3
Mod
5 Mod 2 = 1
+ , 2+15=17
Examples: New Operators only with Integers (whole numbers)
Integer Division: 12\4 à 3 , 17 \3 à 5
Integer Remainder: 12 Mod 4 à 0 , 17 Mod 3 à 2
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A Guide to Working with Visual Logic
Quick Check 1-1, 1-B Pg 12
1-A: A=3, B=5
1.  A+B*5 = 40 or 28?
2.  (2*3)^2 =
3.  11\ A =
4.  2*3^2 =
5.  11 / A =
6.  11 Mod A =
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A Guide to Working with Visual Logic
1-B:
1.  (Exam 1 + Exam 2 + Exam 3)/3
2.  1 + 1 /2 + 1/4
3.  (4*A^2*B)/C
(do you need the parentheses in 3.)
Example: Average
—  Demo in Visual Logic
—  Step Into
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A Guide to Working with Visual Logic
Examples – Odd or Even?
Problem: Given a whole number, N, determine if it
is ODD or EVEN?
Algorithm:
If N Mod 2 equals 0 è N is even
Otherwise è N is odd
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A Guide to Working with Visual Logic
Examples – Coins Change
Problem:
Given a whole number, N < 100, determine how
many quarters, dimes, nickels, pennies make up N
cents with the least # of coins.
Example: N = 92
# of Quarters = 3
# of Dimes = 1
# of Nickels = 1
# of Pennies = 2
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92 / 25 = 3.68
92\25 = 3 ç # of Q
92 Mod 25 = 17 ç remainder or left over
(92 – 3*25 = 92 – 75 = 17 == 92 Mod 25
17 \10 = 1 ç # of D
17 Mod 10 = 7 ç left over
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A Guide to Working with Visual Logic
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A Guide to Working with Visual Logic
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A Guide to Working with Visual Logic
Example
Intrinsic
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Functions inResult
VL
FormatCurrency(12345)
FormatCurrency(.02)
FormatPercent(0.0625)
FormatPercent(0.75)
Abs(-3.3)
Abs(5.67)
Int(3.8)
Int(7.1)
Round(3.8)
Round(7.1)
Random(5)
$12, 345.00
$0.02
6.25%
75.00%
3.3
5.67
3
7
4
7
A random integer between 0 and 4
Random (6) + 1
A random integer between 1 and 6
A Guide to Working with Visual Logic
Table 1-1: Correct Programming Formats
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Value
Written
Format
Programming
Format
Comment
String
Hello World
“Hello World”
Use quotes to
delimit strings
Percent
15%
0.15
Use decimal
format
Dollars
$300
300
Dollar signs not
allowed
Large
Numbers
12,345,678
12345678
Commas not
allowed
A Guide to Working with Visual Logic
Output Statement Summary
—  Output statements are used to display information
—  In Visual Logic, the output flowchart element is a parallelogram
with the keyword Output followed by an output expression
—  When executed, string literals (e.g. “ Dave” or “Quarters “) are
displayed exactly as typed inside the containing quotes
—  When executed, expressions are evaluated and the result is
displayed
—  The ampersand (&) operator maybe used to concatenate a series
of string literals, variables and expressions into one large expression
—  Carriage returns in the output expression appear as carriage returns
in the displayed output
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A Guide to Working with Visual Logic