If–else execution flow in Python - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does an if statement do in Python?

It checks a condition and runs a block of code only if that condition is true.

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What is the purpose of the else block?

The else block runs code when the if condition is false.

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How does Python decide which block to run in an if–else structure?

Python checks the if condition first. If true, it runs the if block. If false, it runs the else block.

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What happens if the if condition is true and there is an else block?

Only the if block runs. The else block is skipped.

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Can you have an if statement without an else?

Yes. The else block is optional. If missing, nothing happens when the if condition is false.

What will this code print?<br>

if 5 > 3:
    print('Yes')
else:
    print('No')

A Yes

B No

C Nothing

D Error

5 is greater than 3, so the if condition is true and 'Yes' is printed.

If the if condition is false and there is no else, what happens?

A The program crashes

B Nothing happens

C The code inside <code>if</code> runs

D The program asks for input

If the condition is false and no else block exists, Python skips the if block and continues.

Which keyword starts the block that runs when the if condition is false?

A elif

B if

C else

D then

The else keyword starts the block that runs when the if condition is false.

What is the correct way to write an if–else statement in Python?

A if condition: do_something else: do_something_else

B if condition then do_something else do_something_else

C if (condition) { do_something } else { do_something_else }

D if condition do_something else do_something_else

Python uses colons and indentation to define blocks, as in option D.

What will this code print?<br>

if False:
    print('A')
else:
    print('B')

A Error

B A

C Nothing

D B

The condition is false, so the else block runs and prints 'B'.

Explain how Python decides which code to run in an if–else statement.

Think about the condition and the two possible paths.

Describe what happens if the if condition is false and there is no else block.

Consider what Python does when no alternative code is given.