Using Loops in Programming Flowcharts and Pseudocode

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Using Loops in ProgrammingFlowcharts and
Pseudocode

• Please use speaker notes for additional
  information!

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condition
processing
Y
N
DO WHILE LOOP The while loop shown here tests a
condition to see if the processing should be
done. If the answer to the condition is YES,
the processing box shown is executed. If the
answer to the condition is NO, the processing box
shown is not executed.
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DO UNTIL LOOP The while loop shown here executes
the processing once and then tests a condition to
see if the processing should be done. This
means that the loop will always be executed once
since it is executed before checking is
done. Once the processing has been done once,
further processing is determined by the answer to
the condition. If the condition gets a YES, then
the processing is executed again. If the
condition gets a NO, then the processing is not
executed again.
processing
condition
Y
N
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DO WHILE LOOP
taxCt 1
taxCt lt 5
Y
Print tax bill
Add 1 to taxCt
Set up tax bill
N

• The looping structure where I want to use the
  while loop to do something a certain number of
  times, requires the following
• initialize the counter outside the loop
• test the counter to determine whether or not to
  enter the loop
• increment the counter inside the loop

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taxCt 1
taxCt lt 5
Y
Print tax bill
Add 1 to taxCt
Set up tax bill
N
Pseudocode
taxCt 1 while taxCt lt 5 set up tax bil
(move information to bill) print tax bill
add 1 to taxCt end-loop
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The loop shown here is executed until there are
no more records on the file.
Start
Process
Housekeeping
Read a record
Process
Not EOF
Loop
Y
Terminate
End-Process
The loop is shown on the next slide.
Stop
Terminate
Housekeeping
Setup data
Close files
Open files
End-Terminate
End-Housekeeping
DO WHILE LOOP
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DO WHILE LOOP
Loop
Set up tax bill information
taxCt 1
taxCt lt 5
Y
Print tax bill
Add 1 to taxCt
Set up tax bill
N
Read a record
The loop shown on this page prints 4 tax bills
for each property owner.
End-Loop
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Pseudocode
Process() read a record while not end of
file loop() end-loop
return end-process
Mainline housekeeping() process()
terminate() stop end-mainline
Loop() set up tax bill information taxCt
1 while taxCt lt 5 set up tax bill
with additional data if needed
print tax bill add 1 to taxCt
end-loop read a record return end-loop

Housekeeping() set up data open files
return end-housekeeping
Terminate() close files
return end-terminate
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Start
Housekeeping
Wrapup
Housekeeping
Setup variables
May not have paid last bill- check
Enter money you have to pay bills
Process
Wrapup
Cannot pay any more bills - moneyAvail
Accept amountAvail
Stop
End-Wrapup
End-Housekeeping
Process is on the next page,
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Process
Because I want to keep this processing simple,
the user must enter the smallest bill first and
move to the largest. So when a bill cannot be
paid, processing is done.
Enter amountBill payTo
Accept amountBill payTo
Note that the only way out of this loop is to
have a bill you cannot afford to pay. This means
if you have no more bills to pay, entering a
large number - more than moneyAvail will cause an
exit.
amountBill lt moneyAvail
Loop
Y
N
End-Process
DO WHILE LOOP
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Loop
Because I want to keep this processing simple,
the user must enter the smallest bill first and
move to the largest. So when a bill cannot be
paid, processing is done.
Set up information to pay bill
Pay bill
Subtract amountBill from moneyAvail
Ask for amountBill payTo
This is where I take in more data. I will then
go back to process where I do the loop if I have
the money to pay the bill.
Accept amountBill payTo
End-Loop
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Mainline housekeeping() process()
wrapup() stop end-mainline
Process() enter amountBill enter payTo
accept amountBill toPay While amountBill lt
moneyAvail loop end-loop
return end-process
Housekeeping() set up data enter money
you have to pay bills accept
amountAvail return end-housekeeping
Loop() set up information to pay bill
print paid bill subtract amountBill from
money Avail enter amountBill enter
payTo accept amountBill payTo
return end-loop
Wrapup() print msg about last bill print
msg about moneyAvail return end-wrapup
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IDENTIFICATION DIVISION.
PROGRAM-ID. C17LOOP. ENVIRONMENT
DIVISION. DATA DIVISION.
WORKING-STORAGE SECTION. 01
INPUT-VARIABLES. 05 AMOUNT-AVAIL
PIC 9(5)V99. 05 AMOUNT-BILL
PIC 9(5)V99. 05 PAY-TO
PIC X(20). 01 OUTPUT-VARIABLES.
05 AMOUNT-BILL-TO-SCR PIC ,.99.
05 AMOUNT-AVAIL-TO-SCR PIC ,.99.

The numbers are input as pure numbers. The V
remembers where the decimal point is if the user
inputs decimal points.
The output wants to include decimal points and
commas if needed. I setup these pictures to show
the edited data I will display on the screen.
Housekeeping
Setup variables
On this slide, I have shown the beginning of the
COBOL program. The PROCEDURE DIVISION where the
actual processing is done is shown on the next
slide. This would correspond to setting up
variables.
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PROCEDURE DIVISION. MAINLINE.
PERFORM A-100-HOUSEKEEPING.
PERFORM B-100-PROCESS. PERFORM
C-100-WRAPUP. STOP RUN.
A-100-HOUSEKEEPING. DISPLAY " " WITH
BLANK SCREEN. DISPLAY " ".
DISPLAY "ENTER THE AMOUNT OF MONEY AVAILABLE".
ACCEPT AMOUNT-AVAIL.
B-100-PROCESS. DISPLAY "ENTER THE
AMOUNT OF THE FIRST BILL". ACCEPT
AMOUNT-BILL. DISPLAY "ENTER WHO TO PAY
THE BILL TO" ACCEPT PAY-TO.
PERFORM B-200-LOOP UNTIL
AMOUNT-BILL gt AMOUNT-AVAIL. B-200-LOOP.
DISPLAY "YOU HAVE PAID THE BILL TO "
PAY-TO. MOVE AMOUNT-BILL TO
AMOUNT-BILL-TO-SCR. DISPLAY "PAID THIS
AMOUNT "AMOUNT-BILL-TO-SCR. SUBTRACT
AMOUNT-BILL FROM AMOUNT-AVAIL. DISPLAY
" ". DISPLAY "ENTER THE AMOUNT OF THE
NEXT BILL". DISPLAY "ENTER THE
SMALLEST BILL LEFT TO PAY" ACCEPT
AMOUNT-BILL. DISPLAY "ENTER WHO TO PAY
THE BILL TO". ACCEPT PAY-TO.
C-100-WRAPUP. DISPLAY "YOU MAY NOT
HAVE PAID THE LAST BILL". DISPLAY
"CHECK THE LISTINGS ON THE SCREEN".
DISPLAY "CANNOT PAY ANY MORE BILLS".
MOVE AMOUNT-AVAIL TO AMOUNT-AVAIL-TO-SCR
DISPLAY "THIS IS WHAT YOU HAVE LEFT "
AMOUNT-AVAIL-TO-SCR.
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PROCEDURE DIVISION. MAINLINE.
PERFORM A-100-HOUSEKEEPING.
PERFORM B-100-PROCESS. PERFORM
C-100-WRAPUP. STOP RUN.
A-100-HOUSEKEEPING. DISPLAY " " WITH
BLANK SCREEN. DISPLAY " ".
DISPLAY "ENTER THE AMOUNT OF MONEY AVAILABLE".
ACCEPT AMOUNT-AVAIL.
Housekeeping
Start
Setup variables
Housekeeping
Enter money you have to pay bills
Process
Accept amountAvail
Wrapup
Stop
End-Housekeeping
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B-100-PROCESS. DISPLAY "ENTER
THE AMOUNT OF THE FIRST BILL". ACCEPT
AMOUNT-BILL. DISPLAY "ENTER WHO TO PAY
THE BILL TO" ACCEPT PAY-TO.
PERFORM B-200-LOOP UNTIL
AMOUNT-BILL gt AMOUNT-AVAIL.
Process
Enter amountBill payTo
Note that in the flowchart I said if amountBill
is lt moneyAvail execute the loop. In the code it
is expressed differently, here I say do the loop
until the amountBill is greater than the
amountAvail. Essentially, I am saying the same
thing but the language of COBOL led me to express
it differently.
Accept amountBill payTo
amountBill lt moneyAvail
Loop
Y
N
End-Process
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B-200-LOOP. DISPLAY "YOU HAVE
PAID THE BILL TO " PAY-TO. MOVE
AMOUNT-BILL TO AMOUNT-BILL-TO-SCR.
DISPLAY "PAID THIS AMOUNT "AMOUNT-BILL-TO-SCR.
SUBTRACT AMOUNT-BILL FROM AMOUNT-AVAIL.
DISPLAY " ". DISPLAY "ENTER
THE AMOUNT OF THE NEXT BILL". DISPLAY
"ENTER THE SMALLEST BILL LEFT TO PAY"
ACCEPT AMOUNT-BILL. DISPLAY "ENTER WHO
TO PAY THE BILL TO". ACCEPT PAY-TO.
Loop
Set up information to pay bill
Pay bill
Subtract amountBill from moneyAvail
Ask for amountBill payTo
Accept amountBill payTo
End-Loop
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C-100-WRAPUP. DISPLAY "YOU MAY
NOT HAVE PAID THE LAST BILL". DISPLAY
"CHECK THE LISTINGS ON THE SCREEN".
DISPLAY "CANNOT PAY ANY MORE BILLS".
MOVE AMOUNT-AVAIL TO AMOUNT-AVAIL-TO-SCR.
DISPLAY "THIS IS WHAT YOU HAVE LEFT "
AMOUNT-AVAIL-TO-SCR.
Wrapup
May not have paid last bill - check
Cannot pay any more bills - moneyAvail
End-Wrapup
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I entered that the amount of money available was
10000
Then I entered the amount of the first bill for
1275.25 and that it was to be paid to JM
Builders. The pament was confirmed.
Now I am being prompted to enter the next bill.
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Now I have paid my second bill for 3000.
This shows the next payment to Heights Roofers.
I then attempted to pay HJ Builders 6000 but I
did not have that amount left and the bill was
not paid. I know this because I received no
confirmation of payment and the message that the
last bill may not have been paid. I also show the
amount of money left.
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The loop shown here is executed until there are
no more records on the file.
Start
Process
Housekeeping
Read a record
Process
Not EOF
Loop
Y
Wrapup
End-Process
The loop is shown on the next slide.
Stop
Wrapup
Set up total line
Housekeeping
Note that I am writing a total line when I Wrapup
this program. I a set up and then I write.
Setup data
Write total line
Open files
Close files
End-Housekeeping
End-Wrapup
DO WHILE LOOP
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Loop
JBCDS
Y
N
Add SAL to TOTAL-SAL
Set up the screen line
Write to the screen
Read a record
End-Loop
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Process() read a record while not end of
file loop() end-loop
return end-process
Mainline housekeeping() process()
terminate() stop end-mainline
Housekeeping() set up data open files
return end-housekeeping
Loop() if JBCD equals S add sal to
total-sal set up the screen line
write the screen line end-if read a record
return end-loop
Terminate() set up total line write total
line close files return end-terminate
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IDENTIFICATION DIVISION. PROGRAM-ID.
CIS17lab. ENVIRONMENT DIVISION.
INPUT-OUTPUT SECTION. FILE-CONTROL.
SELECT EMPLOYEE-FILE ASSIGN TO
"A\EMPLOYEE.DAT". DATA DIVISION.
FILE SECTION. FD EMPLOYEE-FILE
DATA RECORD IS EMPLOYEE-RECORD. 01
EMPLOYEE-RECORD. 05 IDNO PIC
XXXXX. 05 EMPNAME PIC X(20).
05 YRBTH PIC 9(4). 05 GEN
PIC X. 05 MARSTAT PIC
X. 05 NUMDEP PIC 99.
05 ED PIC XXX. 05 JBCD
PIC X. 05 PAYHR PIC 999V99.
05 SAL PIC 9(6)V99.
05 BONUS PIC 9(5). 05 DEPT
PIC 99. 05 STATE PIC XX.
WORKING-STORAGE SECTION. 01
PROG-INDICATORS. 05 END-OF-FILE-IND
PIC XXX VALUE "NO ". 01 WORK-AREAS.
05 TOTAL-SAL PIC 9(8)V99 VALUE
0. 01 OUTPUT-TO-SCR. 05
SAL-FOR-SCR PIC ,.99. 05
TOTAL-SAL-FOR-SCR PIC ,,.99.
Housekeeping
Setup data
Layout of the input file I am reading.
Area to accumulate totals.
Area to layout fields that will appear on the
screen.
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PROCEDURE DIVISION. MAINLINE.
PERFORM A-100-HOUSEKEEPING.
PERFORM B-100-PROCESS. PERFORM
C-100-WRAPUP. STOP RUN.
A-100-HOUSEKEEPING. OPEN INPUT
EMPLOYEE-FILE. DISPLAY " " WITH BLANK
SCREEN. DISPLAY " ".
B-100-PROCESS. READ EMPLOYEE-FILE
AT END MOVE "YES" TO
END-OF-FILE-IND. PERFORM B-200-LOOP
UNTIL END-OF-FILE-IND "YES".
B-200-LOOP. IF JBCD "S"
ADD SAL TO TOTAL-SAL MOVE SAL TO
SAL-FOR-SCR DISPLAY EMPNAME " "
JBCD " " SAL-FOR-SCR END-IF
READ EMPLOYEE-FILE AT END
MOVE "YES" TO END-OF-FILE-IND.
C-100-WRAPUP. DISPLAY " ".
MOVE TOTAL-SAL TO TOTAL-SAL-FOR-SCR.
DISPLAY "TOTAL SALARY FOR SALARIED EMPLOYEES "
TOTAL-SAL-FOR-SCR.
CLOSE EMPLOYEE-FILE.
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PROCEDURE DIVISION. MAINLINE.
PERFORM A-100-HOUSEKEEPING.
PERFORM B-100-PROCESS. PERFORM
C-100-WRAPUP. STOP RUN.
A-100-HOUSEKEEPING. OPEN INPUT
EMPLOYEE-FILE. DISPLAY " " WITH BLANK
SCREEN. DISPLAY " ".
Start
Housekeeping
Process
Wrapup
Housekeeping
Stop
Setup data
Open files
End-Housekeeping
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B-100-PROCESS. READ
EMPLOYEE-FILE AT END
MOVE "YES" TO END-OF-FILE-IND.
PERFORM B-200-LOOP UNTIL
END-OF-FILE-IND YES.
Process
Read a record
Not EOF
Loop
Y
End-Process
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B-200-LOOP. IF JBCD "S" ADD SAL TO
TOTAL-SAL MOVE SAL TO SAL-FOR-SCR
DISPLAY EMPNAME " " JBCD " " SAL-FOR-SCR
END-IF READ EMPLOYEE-FILE AT END
MOVE "YES" TO END-OF-FILE-IND.
Loop
JBCDS
Y
N
Add SAL to TOTAL-SAL
Set up the screen line
Write to the screen
Read a record
End-Loop
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C-100-WRAPUP. DISPLAY " ".
MOVE TOTAL-SAL TO TOTAL-SAL-FOR-SCR.
DISPLAY "TOTAL SALARY FOR SALARIED EMPLOYEES
" TOTAL-SAL-FOR-SCR.
CLOSE EMPLOYEE-FILE.
Wrapup
Write total line
Close files
End-Wrapup
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