Free preview
100 lessons
Python Done Right
Free preview
Python Done Right · 100 lessons
No surprise gaps
Actually remember it
Skip what you know
One subscription. All learning paths included.
Our content is best on a larger screen
The if statement
The if statement runs code only when a condition is True:
if condition:
# indented code runs if condition is True
The indented block (the "body") only executes when the condition evaluates to True. Unindented code runs regardless:
x = 10
if x > 5:
print("x is greater than 5") # runs because 10 > 5 is True
if not
Use if not to check when a condition is False:
has_finished_course = False
if not has_finished_course:
print("Keep going!") # runs because False becomes True with not
Note: Inside a function, we need double indentation:
def my_function(age):
if age > 21:
print("You're over 21!")
Practice questions
4 questions
In the Python Editor, complete the function logic by writing an if statement that assigns the string "C" (for "Credit") to the variable balance_status when the float variable balance is non-negative.
Running the code executes it against a set of test accounts to verify your code and produce a token - what is the token?
Select the correct answer:
+ 3 more questions
Indentation in conditional logic
Indentation defines which code belongs to an if statement:
is_active = True
if is_active:
print("The system is active.") # indented = part of if block
Be careful - unindented code runs regardless of the condition:
is_birthday = True
if is_birthday:
print("Happy Birthday!")
print("Let's celebrate!") # BUG: always runs (not indented)
The second print runs whether is_birthday is True or False.
Practice questions
4 questions
Look at the code in the Python Editor. Which line numbers belong to the if code block and will print when learning_to_program is true?
Select the correct answer:
+ 3 more questions
The else clause
The else clause runs when the if condition is False:
if condition:
# runs when True
else:
# runs when False
Example:
age = 20
citizen = True
if age >= 18 and citizen:
print("You are eligible to vote.")
else:
print("You are not eligible to vote.")
Since both conditions are True, the if block runs. If either were False, the else block would run instead.
Note: The else must be at the same indentation level as its if.
Practice questions
4 questions
In the Python Editor, complete the function body by writing an if-else statement to define a new variable, eligible, such that:
eligible is true when the integer age is greater than or equal to 18 and the integer income is less than 30000;eligible is false otherwise.Running the code generates a token the local council can use to validate your logic - what is this token?
Select the correct answer:
+ 3 more questions