09 - While Loops

Note: The following video provdies a beginner's overview to While loops. Do watch it if possible.

  lops

  loops

  lossy compression

  lexical analysis

For, While, Repeat..Until, Print, Def

  Repeat…Until

  Print and Def are not types of loops

  There is no such thing as a 'for' loop

  All of the items on the list are valid loops

  subtract / final

  function / starting

  repeat / stopping

  define / variable

Note: Repeat …Until loops exist in languages like VB.Net but are not called this in Python. 

  All the options listed here apply

  A while loop has its stopping condition at the start

  A while loop has no stopping condition

  A while loop has its stopping condition at the end

  FALSE

  TRUE

def main():
    i=0
    while i<10:
        print(i)

main()

  An infinite loops of 0s (zeros)

  0

  1,2,3,4,5,6,7,8,9,10

  0,1,2,3

def main():
    i=0 #this is the value of i to start with (initial value)
    while i<10: #this is the condition of the loop
        #i will be printed because the condition is true
        print(i)#i is still 0, and it will be printed forever!
        #What can we add here to make it print 0,1,2,3,4,5,6,7,8,9?
main()

  replace the last comment with i+0 (this will add 0 to the value of i)

  simple replace the last comment with i=i+1 (this will increase the value of i until it reaches 10)

  None of the above

  replace the last comment with i+9 (this will add 9 to the value of i)

def main():
    i=2
    while i<10:
        print(i)
        i=i+2

main()

  Change the stopping condition to: while i>12:

  Change the stopping condition to: while < 12 MOD 3

  Change the stopping condition to: while i<12:

  Change the stopping condition to: while i=12

#Option 1
==========
def main():
    i=1
    while i<11:
        print(i)
        i=i+1
main()


#Option 2
==========
def main():
    i=10
    while i>0:
        print(i)
        i=i-1
main()



#Option 3
==========
def main():
    i=1
    while i>10:
        print(i)
        i=10-1
main()

  Option 2

  Option 1

  Option 3

  None of the above

def main():
    password_correct=False
    while password_correct==False:
        password=input("Please enter your password:")
        if password=="open123":
            password_correct=False


    print("Password correct - exit the loop")
    
main()

  Because the condition to exit the loop is never met (change password_correct=False on line 6 to True)

  None of the above

  Because open123 is not the set password (numbers are not permitted)

  Because the IF statement inside the while loop has been set up incorrectly (it shoud have a single equals sign)

def gameplay():
    score=8
    while score<11:
        print(score)
        score=score+1
    print("Exit Game")
    
gameplay()

  Thes score starts at 8 and inside the loop the output is 8,9,10,11 before there is an error

  The score starts at 8, the loop outputs 8,9,10 and then exits the loop to print "Exit game"

  None of the above

  The score starts at 0, as always, the loop outputs 0 to 10, and then exits the game

x=5
while x<4:
    print(x)
    x=x+1

  Change line 2 to: while x =5:

  Both changing line 2 to: while x==5 and changing line 2 to: while x<6: will work to produce an output of 5

  Change line 2 to: while x<6:

  Change line 2 to: while x==5:

  unless the condition is met, the code inside the loop may not run at all

  even if the condition isn't met, the code in the loop will run at least once

  None of the above

  when the condition is met, the while loop will delete itself

  While the health of a character is greater than 0, then continue gameplay

  A while loop could be used to replace a function, as while loops are functions

  A while loop could be used to import and generate random numbers

  A while loop could be used to print output directly to the printer

  In a for loop the condition to stop the loop is at the end

  In a for loop, the number of iterations are known and declared in advanced (e.g. from 0 to 10)

  All of the above apply

  In a for loop the stopping condition is always sandwiched in the middle