While loops

Intermediate Julia

Anthony Markham

Quantitative Developer

While loops - syntax

Less common than the for loop, but still useful in some cases.
Repeat the expression while the condition is true.
Often used to repeat an action until a certain condition is met.

while condition
    expression
end

While loops - example

Repeat a set of actions until a condition is true

counter = 10
while counter != 0
    print(counter, " ")
    counter = counter - 1
end

10 9 8 7 6 5 4 3 2 1

While loops - example first iteration

# First iteration
counter = 10
while counter != 0  # counter = 10 here, so this is true
    print(counter, " ")  # print counter, equal to 10
    counter = counter - 1  # decrease the value of counter by 1
end

While loops - example second iteration

# Second iteration
counter = 10
while counter != 0  # counter now = 9 here, so this is true
    print(counter, " ")  # print counter, equal to 9
    counter = counter - 1  # decrease the value of counter by 1
end

10 9

While loops - example third iteration

# Third iteration
counter = 10
while counter != 0  # counter now = 8 here, so this is true
    print(counter, " ")  # print counter, equal to 8
    counter = counter - 1  # decrease the value of counter by 1
end

10 9 8

While loops - infinite loop

What will happen if we forget to decrement the counter variable?

# Second iteration
counter = 10
while counter != 0  # counter now = 9 here, so this is true
    print(counter, " ")  # print counter, equal to 9
end

10 10 10 10 10 10 10 10 10

While loops - termination

In the DataCamp environment, an infinite loop will cause the session to disconnect
On your local machine, terminate the Julia program using Ctrl + C

Let's practice!

Intermediate Julia