1. Module 4
Loops and Repetition
4/4/2019
CSE 1321 Module 4

2. Ps Initial Problem int counter = 1 while (counter < 1000) {
PRINT (counter + “I will not…”)
counter++ }
counter Ps

3. Code counter = 1 while (counter <= 1000):
print (counter, " I will not...")
counter = counter + 1

4. Pseudocode – Input Validation Example
userGuess ← 0, secretNumber ← 5 PRINT “Enter a number between 1 and 10” READ userGuess WHILE (userGuess < 1 OR userGuess > 10) PRINT “That is not between 1 and 10. Try again.” READ userGuess ENDWHILE IF (userGuess == secretNum) THEN PRINT “That’s right! ”, userGuess, “ is the secret!” ELSE PRINT userGuess, “ is not the secret!” ENDIF Ps
4/4/2019
CSE 1321 Module 4

5. Python - Input Validation Example
secretNumber = 5 userGuess = int(input("Enter a number between 1 and 10: ")) while(userGuess < 1 or userGuess >10): userGuess = int(input("Not between 1 and 10! Try again!")) if(userGuess == secretNumber): print("That's right! ", userGuess, " is the secret number!") else: print(userGuess, " is not the secret number!")
4/4/2019
CSE 1321 Module 4

6. Pseudocode – do-while Loop Example
CREATE number ← 0, lastDigit ← 0, reverse ← 0
PRINT “Enter a positive number.”
READ number
DO lastDigit ← number % 10
reverse ← (reverse * 10) + lastDigit
number ← number / 10
WHILE (number > 0) ENDDO Ps
4/4/2019
CSE 1321 Module 4

7. Python – do-while Loop Example
number = 0
lastDigit = 0
reverse = 0
number = int(input("Enter a positive integer: "))
helperVariable = True
while (helperVariable == True):
lastDigit = number % 10
reverse = (reverse * 10) + lastDigit
number = (int)(number / 10)
print (number, ":", reverse)
if (number >= 1):
else:
helperVariable = False
print("The number reversed is: ", reverse)
Note: Python does not have an explicit do-while loop, However, one way is to use a helper
variable
4/4/2019
CSE 1321 Module 4

8. Pseudocode – for Loop Example
CREATE userChoice ← 0
PRINT “Choose a number to see the multiplication table.”
READ userChoice
FOR (multiplier ← 1, multiplier < 12, multiplier ← multiplier + 1) PRINT userChoice, “ * “, multiplier, “ = “, (multiplier * userChoice) ENDFOR Ps
4/4/2019
CSE 1321 Module 4

9. Python – for Loop Example
choice = int(input("Enter the number for the table: "))
for multiplier in range(1, 13): print(multiplier, " * ", choice, " = ", multiplier * choice)
We can add a parameter to define the incrementation, if it is other than 1. For instance, the code below will show the choice multiplied only by even numbers
for multiplier in range(2, 13, 2):
print(multiplier, " * ", choice, " = ", multiplier * choice)
4/4/2019
CSE 1321 Module 4

10. Pseudocode – Nested for Loop Example
CREATE maxRows ← 10, row, star
FOR (row ← 1, row < maxRows, row ← row + 1)
FOR (star ← 1, star <= row, star ← star + 1)
PRINT “*”
ENDinnerFOR
PRINTLINE () ENDouterFOR Ps
4/4/2019
CSE 1321 Module 4

11. Python – Nested for Loop Example
# Demonstrates the use of nested for loops to print stars
rows = 10
for row in range(1,11):
for star in range(1, row):
print("*", end = "")
print()
4/4/2019
CSE 1321 Module 4