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Lecture 11

# ISYS2157 Lecture Notes - Lecture 11: Infinite Loop, Checkbox, Carriage ReturnPremium

3 pages20 viewsFall 2016

Department
Information Systems
Course Code
ISYS2157
Professor
James Gips
Lecture
11

Page:
of 3
Introduction to Programming
Lecture #11
9.21.16
Event handlers
oButton pressers
oText change
Speeding example
oCheckbox for construction
oInput speed limit
oButton press – event
Declarations
Inputs
Check inputs for error
Try catch and if statements – check and see if number is
reasonable
Calculations
Display results
Combine
oCheckbox – make false
Then check it in your program
Boolean
Textbox
oWord wrap – true
oMultiline – true
oNo need for vertical scroll bars
Not all variable need to be declared at the top of the program
&
oConcatenation – joins two strings together
o+ Also does the same thing for concatenation
Dim S as String
S = “Boston” & “College”
S = S & “Eagles”
Boston College Eagles
Control structures
oHow control of a program/statement is dictated
Event handler
Sequencing
Try catch
IF, THEN, ELSE
Loops
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Loops
oAllow you to do the same sequence of statements over and over again
ovbCRLF
Visual basic carriage return line feed
Same thing as enter
For Loop
oFor N = F to T
N – next
N = index variable
F = beginning value
T = ending value
Each line is produced by one time through the loop
Lecture #12
9.28.16
Do While Conditions
Statements
Loop
If true then go through the loop
Ex.
X = 2
DO while x<7
X=x+1
B = 2*x
Loop
2<7
X = 2 + 1
B = 2*3
Do the loop again until x<7 is false and not true
The loop must at some point be false otherwise it’ll be an infinite loop since it is
always true
Ex.
X = 2
Do while x<7
Y = 23
Loop
X<7; 2<7 will always be true so it continues through
Do Until Loop
Used to repeat a group of statement until it is true
LINES MATTER – go to new line for each one
Exit Statement
Allows you to exit a loop
oSome people really don’t like the exist statement
NPer Example
Have Amount, Rate, Goal
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See how long it takes for the Amount you invest to get to the Goal at a given rate
oAmount must be less than Goal otherwise it won’t take any time to get to
the Goal
Debug Mode
Looking for errors
Release – ready to release program since found all the errors
Debug – Windows – Local
oTells you all of the values of the variables right now
oHelps find logical errors
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