Boolean Basics
Every decision your program makes—whether to show a message, repeat a step, or validate input—boils down to a Boolean: True or False. This chapter introduces Booleans and how ordinary Python values behave in conditions.
What is a Boolean?
A Boolean is a value that represents truth: True or False (note the capitalization). You'll often get Booleans from comparisons—age >= 18 yields True when the condition holds—and you'll use them directly in control flow, e.g. if is_adult:.
Truthiness in practice
In if/while conditions, Python treats many objects as "truthy" or "falsey". Empty or zero-like values are considered false; everything else is true. This lets you write natural checks such as if items: or if name: without extra comparisons.
Common falsey values
False;None;0,0.0;""(empty string);- Empty containers:
[],(),{},set().
Non-empty strings are truthy—even "0" or "False".
12345678910is_ready = True name = "" count = 0 if is_ready: print("Go!") # runs, because True print(bool(name)) # False → empty string print(bool(count)) # False → zero print(bool("0")) # True → non-empty string
1. Which value is falsey in Python?
2. What value will this code output?
3. Which if will not execute its body?
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Can you explain more about truthy and falsey values in Python?
What are some common mistakes when using Booleans in conditions?
Can you give more examples of how Booleans are used in control flow?
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Sveip for å vise menyen
Every decision your program makes—whether to show a message, repeat a step, or validate input—boils down to a Boolean: True or False. This chapter introduces Booleans and how ordinary Python values behave in conditions.
What is a Boolean?
A Boolean is a value that represents truth: True or False (note the capitalization). You'll often get Booleans from comparisons—age >= 18 yields True when the condition holds—and you'll use them directly in control flow, e.g. if is_adult:.
Truthiness in practice
In if/while conditions, Python treats many objects as "truthy" or "falsey". Empty or zero-like values are considered false; everything else is true. This lets you write natural checks such as if items: or if name: without extra comparisons.
Common falsey values
False;None;0,0.0;""(empty string);- Empty containers:
[],(),{},set().
Non-empty strings are truthy—even "0" or "False".
12345678910is_ready = True name = "" count = 0 if is_ready: print("Go!") # runs, because True print(bool(name)) # False → empty string print(bool(count)) # False → zero print(bool("0")) # True → non-empty string
1. Which value is falsey in Python?
2. What value will this code output?
3. Which if will not execute its body?
Takk for tilbakemeldingene dine!
