-
-
Notifications
You must be signed in to change notification settings - Fork 1.5k
Concept Conditionals Add Files #2430
New issue
Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.
By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.
Already on GitHub? Sign in to your account
Merged
BethanyG
merged 9 commits into
exercism:main
from
BethanyG:concept-conditionals-cleanup
May 30, 2021
Merged
Changes from all commits
Commits
Show all changes
9 commits
Select commit
Hold shift + click to select a range
9dc6f6e
Created about, introduction and links files.
BethanyG f543999
Added authors and blurb info for conditionals concept.
BethanyG 629f893
Created about, introduction and links files.
BethanyG 84ef304
Added authors and blurb info for conditionals concept.
BethanyG a2757be
Merge branch 'concept-conditionals-cleanup' of https://github.com/Bet…
BethanyG ef0c1b7
Apply suggestions from code review
BethanyG 8f009d9
Apply suggestions from code review
BethanyG 570e60b
Attempted to remove hidden CLRF chars in code example. May have failed.
BethanyG 90c4725
Resolved merge conflicts from upstream code review edits, attempted t…
BethanyG File filter
Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
There are no files selected for viewing
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -1,5 +1,5 @@ | ||
| { | ||
| "blurb": "TODO: add blurb for this concept", | ||
| "authors": ["bethanyg", "cmccandless"], | ||
| "blurb": "The conditionals 'if', 'elif' ('else + if'), and 'else' are used to control the flow of execution and make decisions in a program. Python doesn't have a formal case-switch statement ,and uses multiple 'elif's to serve a similar purpose. Conditionals pair with expressions and objects that must resolve to 'True' or 'False'.", | ||
| "authors": ["bethanyg", "sachsom95"], | ||
| "contributors": [] | ||
| } |
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -1,2 +1,158 @@ | ||
| #TODO: Add about for this concept. | ||
| # About | ||
|
|
||
| In Python, [`if`][if statement], `elif` (_a contraction of 'else and if'_) and `else` statements are used in Python to [control the flow][control flow tools] of execution and make decisions in a program. | ||
| Unlike many other programming languages, Python versions 3.9 and below do not offer a formal case-switch statement, instead using multiple `elif` statements to serve a similar purpose. | ||
|
|
||
| Python 3.10 introduces a variant case-switch statement called `pattern matching`, which will be covered separately in another concept. | ||
|
|
||
| Conditional statements use expressions that must resolve to `True` or `False` -- either by returning a `bool` directly, or by evaluating ["truthy" or "falsy"][truth value testing]. | ||
|
|
||
|
|
||
|
|
||
| ```python | ||
| x = 10 | ||
| y = 5 | ||
|
|
||
| # The comparison '>' returns the bool 'True', | ||
| # so the statement is printed. | ||
| if x > y: | ||
| print("x is greater than y") | ||
| ... | ||
| >>> x is greater than y | ||
| ``` | ||
|
|
||
| When paired with `if`, an optional `else` code block will execute when the original `if` condition evaluates to `False`: | ||
|
|
||
| ```python | ||
| x = 5 | ||
| y = 10 | ||
|
|
||
| # The comparison '>' here returns the bool False, | ||
| # so the 'else' block is executed instead of the 'if' block. | ||
| if x > y: | ||
| print("x is greater than y") | ||
| else: | ||
| print("y is greater than x") | ||
| ... | ||
| >>> y is greater than x | ||
| ``` | ||
|
|
||
| `elif` allows for multiple evaluations/branches. | ||
|
|
||
| ```python | ||
| x = 5 | ||
| y = 10 | ||
| z = 20 | ||
|
|
||
| # The elif statement allows for the checking of more conditions. | ||
| if x > y: | ||
| print("x is greater than y and z") | ||
| elif y > z: | ||
| print("y is greater than x and z") | ||
| else: | ||
| print("z is great than x and y") | ||
| ... | ||
| >>> z is great than x and y | ||
| ``` | ||
|
|
||
| [Boolen operations][boolean operations] and [comparisons][comparisons] can be combined with conditionals for more complex testing: | ||
|
|
||
| ```python | ||
|
|
||
| >>> def classic_fizzbuzz(number): | ||
| if number % 3 == 0 and number % 5 == 0: | ||
| return 'FizzBuzz!' | ||
| elif number % 5 == 0: | ||
| return 'Buzz!' | ||
| elif number % 3 == 0: | ||
| return 'Fizz!' | ||
| else: | ||
| return str(number) | ||
|
|
||
| >>> classic_fizzbuzz(15) | ||
| 'FizzBuzz!' | ||
|
|
||
| >>> classic_fizzbuzz(13) | ||
| '13' | ||
| ``` | ||
|
|
||
| Conditionals can also be nested. | ||
|
|
||
| ```python | ||
| >>> def driving_status(driver_age, test_score): | ||
| if test_score >= 80: | ||
| if 18 > driver_age >= 16: | ||
| return "Student driver, needs supervision." | ||
| elif driver_age == 18: | ||
| return "Permitted driver, on probation." | ||
| elif driver_age > 18: | ||
| return "Fully licensed driver." | ||
| else: | ||
| return "Unlicensed!" | ||
|
|
||
|
|
||
| >>> driving_status(63, 78) | ||
| 'Unlicsensed!' | ||
|
|
||
| >>> driving_status(16, 81) | ||
| 'Student driver, needs supervision.' | ||
|
|
||
| >>> driving_status(23, 80) | ||
| 'Fully licsensed driver.' | ||
| ``` | ||
|
|
||
| ## Conditional expressions or "ternary operators" | ||
|
|
||
| While Python has no specific `?` ternary operator, it is possible to write single-line `conditional expressions`. | ||
| These take the form of `<value if True>` if `<conditional test>` else `<value if False>`. | ||
| Since these expressions can become hard to read, it's recommended to use this single-line form only if it shortens code and helps readability. | ||
|
|
||
|
|
||
| ```python | ||
| def just_the_buzz(number): | ||
| return 'Buzz!' if number % 5 == 0 else str(number) | ||
|
|
||
| >>> just_the_buzz(15) | ||
| 'Buzz!' | ||
|
|
||
| >>> just_the_buzz(10) | ||
| '10' | ||
| ``` | ||
|
|
||
| ## Truthy and Falsy | ||
|
|
||
| In Python, any object can be tested for [truth value][truth value testing], and can therefore be used with a conditional, comparison, or boolean operation. | ||
| Objects that are evaluated in this fashion are considered "truthy" or "falsy", and used in a `boolean context`. | ||
|
|
||
| ```python | ||
| >>> def truthy_test(thing): | ||
| if thing: | ||
| print('This is Truthy.') | ||
| else: | ||
| print("Nope. It's Falsey.") | ||
|
|
||
|
|
||
| # Empty container objects are considered Falsey. | ||
| >>> truthy_test([]) | ||
| Nope. It's Falsey. | ||
|
|
||
| >>> truthy_test(['bear', 'pig', 'giraffe']) | ||
| This is Truthy. | ||
|
|
||
| # Empty strings are considered Falsey. | ||
| >>> truthy_test('') | ||
| Nope. It's Falsey. | ||
neenjaw marked this conversation as resolved.
Show resolved
Hide resolved
|
||
|
|
||
| >>> truthy_test('yes') | ||
| This is Truthy. | ||
|
|
||
| # 0 is also considered Falsey. | ||
| >>> truthy_test(0) | ||
| Nope. It's Falsey. | ||
neenjaw marked this conversation as resolved.
Show resolved
Hide resolved
|
||
| ``` | ||
|
|
||
| [if statement]: https://docs.python.org/3/reference/compound_stmts.html#the-if-statement | ||
| [control flow tools]: https://docs.python.org/3/tutorial/controlflow.html#more-control-flow-tools | ||
| [truth value testing]: https://docs.python.org/3/library/stdtypes.html#truth-value-testing | ||
| [boolean operations]: https://docs.python.org/3/library/stdtypes.html#boolean-operations-and-or-not | ||
| [comparisons]: https://docs.python.org/3/library/stdtypes.html#comparisons | ||
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -1,2 +1,82 @@ | ||
| #TODO: Add introduction for this concept. | ||
| # Introduction | ||
|
|
||
| In Python, [`if`][if statement], `elif` (_a contraction of 'else and if'_) and `else` statements are used in Python to [control the flow][control flow tools] of execution and make decisions in a program. | ||
| Unlike many other programming languages, Python versions 3.9 and below do not offer a formal case-switch statement, instead using multiple `elif` statements to serve a similar purpose. | ||
|
|
||
| Python 3.10 introduces a variant case-switch statement called `pattern matching`, which will be covered separately in another concept. | ||
|
|
||
| Conditional statements use expressions that must resolve to `True` or `False` -- either by returning a `bool` directly, or by evaluating ["truthy" or "falsy"][truth value testing]. | ||
|
|
||
|
|
||
| ```python | ||
| x = 10 | ||
| y = 5 | ||
|
|
||
| # The comparison '>' returns the bool 'True', | ||
| # so the statement is printed. | ||
| if x > y: | ||
| print("x is greater than y") | ||
| ... | ||
| >>> x is greater than y | ||
| ``` | ||
|
|
||
| When paired with `if`, an optional `else` code block will execute when the original `if` condition evaluates to `False`: | ||
|
|
||
| ```python | ||
| x = 5 | ||
| y = 10 | ||
|
|
||
| # The comparison '>' here returns the bool False, | ||
| # so the 'else' block is executed instead of the 'if' block. | ||
| if x > y: | ||
| print("x is greater than y") | ||
| else: | ||
| print("y is greater than x") | ||
| ... | ||
| >>> y is greater than x | ||
| ``` | ||
|
|
||
| `elif` allows for multiple evaluations/branches. | ||
|
|
||
| ```python | ||
| x = 5 | ||
| y = 10 | ||
| z = 20 | ||
|
|
||
| # The elif statement allows for the checking of more conditions. | ||
| if x > y: | ||
| print("x is greater than y and z") | ||
| elif y > z: | ||
| print("y is greater than x and z") | ||
| else: | ||
| print("z is great than x and y") | ||
| ... | ||
| >>> z is great than x and y | ||
| ``` | ||
|
|
||
| [Boolen operations][boolean operations] and [comparisons][comparisons] can be combined with conditionals for more complex testing: | ||
|
|
||
| ```python | ||
|
|
||
| >>> def classic_fizzbuzz(number): | ||
| if number % 3 == 0 and number % 5 == 0: | ||
| return 'FizzBuzz!' | ||
| elif number % 5 == 0: | ||
| return 'Buzz!' | ||
| elif number % 3 == 0: | ||
| return 'Fizz!' | ||
| else: | ||
| return str(number) | ||
|
|
||
| >>> classic_fizzbuzz(15) | ||
| 'FizzBuzz!' | ||
|
|
||
| >>> classic_fizzbuzz(13) | ||
| '13' | ||
| ``` | ||
|
|
||
| [if statement]: https://docs.python.org/3/reference/compound_stmts.html#the-if-statement | ||
| [control flow tools]: https://docs.python.org/3/tutorial/controlflow.html#more-control-flow-tools | ||
| [truth value testing]: https://docs.python.org/3/library/stdtypes.html#truth-value-testing | ||
| [boolean operations]: https://docs.python.org/3/library/stdtypes.html#boolean-operations-and-or-not | ||
| [comparisons]: https://docs.python.org/3/library/stdtypes.html#comparisons |
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -1,18 +1,22 @@ | ||
| [ | ||
| { | ||
| "url": "http://example.com/", | ||
| "description": "TODO: add new link (above) and write a short description here of the resource." | ||
| "url": "https://docs.python.org/3/tutorial/controlflow.html#more-control-flow-tools", | ||
| "description": "Python Docs: Control flow tools." | ||
| }, | ||
| { | ||
| "url": "http://example.com/", | ||
| "description": "TODO: add new link (above) and write a short description here of the resource." | ||
| "url": "https://docs.python.org/3/library/stdtypes.html#truth-value-testing", | ||
| "description": "Python Docs: Truth value testing." | ||
| }, | ||
| { | ||
| "url": "http://example.com/", | ||
| "description": "TODO: add new link (above) and write a short description here of the resource." | ||
| "url": "https://docs.python.org/3/library/stdtypes.html#boolean-operations-and-or-not", | ||
| "description": "Python Docs: Standard Types - boolean operations." | ||
| }, | ||
| { | ||
| "url": "http://example.com/", | ||
| "description": "TODO: add new link (above) and write a short description here of the resource." | ||
| "url": "https://docs.python.org/3/library/stdtypes.html#comparisons", | ||
| "description": "Python Docs: Comparisons." | ||
| }, | ||
| { | ||
| "url": "https://realpython.com/python-conditional-statements/", | ||
| "description": "Real Python: Conditional statements in Python." | ||
| } | ||
| ] |
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
Uh oh!
There was an error while loading. Please reload this page.