Python while loop

A while loop is used when

• You know how many times you are going to loop

• You want to loop for an unknown number of times, and possibly forever

• You only want to run the code in the loop once

• You see the word while in the problem description

For the code shown, what will happen?

• It will print all the numbers from 0 to 11

• It will print all the numbers from 0 to 11 in increments of 3

• Infinite loop

• It will not run (Syntax error)

For the code shown, what will happen?

• It will print all the numbers from 0 to 11

• It will print all the numbers from 0 to 11 in increments of 3

• Infinite loop

• It will not run (Syntax error)

Why is iteration important?

• It determines the order in which instructions are carried out

• It allows code to be simplified by removing duplicated steps into a block that can be executed many times

• It allows multiple paths through a program

• It ensures the code works correctly

What is the final value of the variable 'number'?

What is the output?

• 5

  4

  3

  2

  1

• 5 4 3 2 1

• 4

  3

  2

  1

  0

• 4 3 2 1 0

What is the output?

• 12 9 6 3 0

• 0 3 6 9 12

• 0 3 6 9

• 9 6 3 0

A counter is (check ALL that apply)

• A variable used in a loop to count the number of times something happened

• usually initialised to zero

• usually incremented inside the loop

• a person with a pen and paper

• used only outside of the loop

What is the output?

• 0 5 10

• 5 10

• 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120 125 130 135 140......etc

• 12 7 2

What is the output?

• 12 17 22

• 12

• 5

• 5 10