The if statement

Learn condition checks with if.

The if statement

An if statement runs a block when a condition is true. The condition goes after if, before a colon:

age = 18
if age >= 18:
    print("Adult")

When the condition is True it runs the indented block; when False it skips it. Indentation defines the block; four spaces is standard. This structure is the basis of decisions.

The boundary of the if block

Indentation shows where the if block ends. Indented lines are part of the block; when indentation stops, the block ends.

if True:
    print("Inside the block")
    print("Still inside")
print("Outside the block")

Inconsistent indentation raises IndentationError. All lines in a block must share the same indent.

Exercise Print a decision with if

Assign score = 85. Inside an if score >= 50: block, print print("Passed").

Show example solution

score = 85
if score >= 50:
    print("Passed")

Test yourself

If age is 20, what does if age >= 18: print("Adult") do?
- Nothing
- Raises an error
- Prints Adult
- Runs else
Show answer

Prints Adult — 20 >= 18 is True, so print runs.

Complete the if condition

age = 18
if age ____ 18:
    print("Adult")

Show answer

age = 18
if age >= 18:
    print("Adult")

Match the if concepts

if

Condition
:

Opening a block
indent

Defining the block
True

Condition is true

Next lesson: elif and else

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