📝 Introduction to while Loops

Structure

While loops are executed until the logical expression evaluates to false.

while logical_expression:
    # code_block is repeated until logical expression is false
    code_block

Which loop to use?

Therefore, while loops are appropriate when the number of times the code block needs to be executed is indefinite.

for loops are appropriate when the number of times the code block needs to be executed is definite or well understood.

When using while loops, ensure that the loop does not run infinitely, which it will if the logical expression never becomes false.

Which one(s) of these loops will run infinitely?

Try to evaluate it without executing the code.

# Option A
x = 1
while x >= 0:
    x /= 0.1

# Option B
x = 1
while x >= 0:
    x -= 0.1

# Option C
x = -4
while x < 0:
    if x % 2 == 0:
        x -= 1
    else: 
        x += 1

Interrupt infinite loops

If you accidentally execute an infinite loop, interrupt the execution by clicking the ◼️ beside the ▶ at the top of the JupyterLab screen.