Fourth Quarter
Involves loops or cycles
◦Loops: means that a process may berepeated as long as certain conditionremains true or remains false.
◦Means “multiple processing”
Provides means of repeating apart of instruction withoutrewriting the part again and again.
Body of the Loop : Set ofstatements which isrepeated.
Loop Exit Condition:condition to be testedbefore each repetition.
Start : the starting or thebeginning point of theloop.
One may start with firstor the last record in thefile.
Step : the manner onhow the records are tobe processed in thegiven file.
Proper sequencing isneeded (ascending ordescending).
Stop : the ending point .It is normallyrepresented in a form ofa conditional expression,thus, a decision symbolis used in the flowchart
Is a variable that defines thestarting, ending point and step ofa looping statement.
It should be a variable that willuniquely identify all the records inthe file.
It is a representation of a field inthe record. The shorter the value,the better is the field
Draw a flowchart that will read the grades in PT,CS and QS of student. Compute the average ofthe student. Print the name and the computedaverage.
Input :
Process:
Output:
Will there be multiple processing? How many times theinputting, processing and outputting will be performed?WHY?
Draw a flowchart that will read the grades in PT,CS and QS of all the students in the class of II -____. Compute the average of all the students.Print the names and the computed averages.
Input :
Process:
Output:
Will there be multiple processing? How many times theinputting, processing and outputting will be performed?WHY?
Are used to literally count the number oftimes a portion of the flowchart is traced.
Need to be initialized / prepared prior to itsuse or application.
The operation involved is “addition”
The increment value is a constant
Example: C = C + 1
Increment Value
Current Value
New Value
A numerical value that collects the result of arepeated mathematical operation.
Used to keep a running total of an item / theoperation involved is “addition”.
Need to be initialized / prepared prior to itsuse or application.
The incremental value is a “variable”(subjected to change)
Example: S = S + N
Increment Value
Current Value
New Value
Executes a group of instructionsrepeatedly
Has 3 Structures:
◦For ……. Next
◦Do …….. Loop : has three types:
Do While …. Loop
Do Until …. Loop
Do …… Loop while
◦While ….. Wend
Executes a section of the code aspecified number of times.
Begins with the “for” statement andends with the “next” statement.
Can only be used if the programmerknows the number of times the loopmust be performed prior to itsexecution.
For <counter > = <Start> to<Stop> Step <Step>
<Statements>
Next <counter>
Dim UserName as string
Dim times as integer
Username = “Paul”
Lbloutput.text = “ ”
For times = 1 to 10 step 1
Lbloutput.text =lbloutput.text & chr(13) &Username
Next times
Dim UserName as string
Dim times as integer
Username = “Paul”
Lbloutput.text = “ ”
For times = 1 to 10
Lbloutput.text =lbloutput.text & chr(13)& Username
Next
For <counter > = <Start> to<Stop> Step <Step>
<Statements>
Next <counter>
Dim counter as integer
Lbloutput.text = “”
For counter = 10 to 1 step -1
lbloutput.text =lbloutput.text & chr(13) &counter
Next
Dim counter as integer
Lbloutput.text = “”
For counter = 9 to 1 step -2
lbloutput.text =lbloutput.text & chr(13) &counter
Next
Most common statement among thedo ..loop statements
Test condition appears at the TOP ofthe loop
◦As long as the test condition is TRUE, theblock of code in the body of the loop willbe continuously executed
◦When the test condition becomes FALSE,the loop terminates.
Condition before iteration
Do while <condition>
<statement>
<statement>
Loop
Private Sub Command1_Click( )
Dim N As Integer
N = 0
Do While N < 10
N = N + 1
Print N
Loop
End Sub
Private Sub Command1_Click( )
Dim N As Integer
N = 0
Do While N < 10
N = N + 1
Print N
Loop
End Sub
Loop Statement
The test condition appearsat the bottom of the loop.
When the test conditionstays TRUE, the loop stillexecutes until it becomesfalse
Condition after iteration
Do
< statement >
< statement >
< statement >
Loop while < condition >
Private Sub Command1_Click( )
Dim N As Integer
N = 0
Do
N = N + 1
Print N
Loop While N < 10
End Sub
Test condition also appearsat the TOP of the LOOP.
Executes the block ofstatements as long as thetest condition is FALSE
Do until < condition >
< statement >
< statement >
Loop
Private Sub Command1_Click( )
Dim N As Integer
N = 0
Do Until N >= 10
N = N + 1
Print N
Loop
End Sub
DO WHILE / DO UNTILDO WHILE / DO UNTIL
Display numbers fromDisplay numbers from
1 to 101 to 10
Do While N < 10Do While N < 10
N = N + 1N = N + 1
Print NPrint N
Body of Loop will be executedas long as the condition isTRUE.Body of Loop will be executedas long as the condition isTRUE.
Display numbers fromDisplay numbers from
1 to 101 to 10
Do Until N >= 10Do Until N >= 10
N = N + 1N = N + 1
Print NPrint N
Body of Loop will be executedas long as the condition isFALSE.Body of Loop will be executedas long as the condition isFALSE.
Hands – On Session
a.Make a program that will displaythis output on the form:
b.Make a program that will display“Patience is a Virtue” 5 times.
Filenames:
◦Activity No.1
4Act12CN
◦Activity No.2
4Act22CN