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[Refactor Concept]: conditionals (#1597)
* Refactor conditionals in Ruby concepts and add new links * Changes based on feedback
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‎concepts/conditionals/.meta/config.json

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{
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"blurb": "Ruby has several constructs to conditionally execute code: if statements, unless statements and case statements.",
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"authors": ["dvik1950"],
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"blurb": "Ruby has conditionals to control the flow of your program. You can use if, unless to control the flow of your program.",
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"authors": ["dvik1950", "meatball133"],
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"contributors": ["kotp", "iHiD"]
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}

‎concepts/conditionals/about.md

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# About
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# Conditionals
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An `if` statement can be used to conditionally execute code:
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Ruby has what is known as flow control expressions, these are used to control the way the program will run and they take a truthy or falsey value.
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There are operators that can be used to create truthy or falsey values, these are known as [comparison operators][comparison-operators].
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There are two main control expressions that are used to control which code will run and which will not.
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Also known as which given branch will run.
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Those two are: `if` and the `unless` expression.
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## Comparison operators
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[Comparison operators][comparison-operators] are used to compare values and return a `true` or `false` value.
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The following operators require two values to be compared of the same type.
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If the values are not of the same type then the compiler will throw an error.
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Here is a list of the operators and an example of when they give a `true` value:
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| Method | Description | Example |
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| ------ | --------------------- | ------- |
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| < | less than | 5 < 4 |
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| <= | less than or equal | 4 <= 4 |
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| > | greater than | 3 > 1 |
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| >= | greater than or equal | 2 >= 2 |
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The equal and not equal operators can be used to compare any type of value contrary to the operators already mentioned.
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The `==` operator is used to check if two values are equal, and that includes checking the type of the value.
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The `!=` works the same way but it will return `true` if the values are not equal and `false` if they are equal.
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Here is a list of the equal and not equal operators and an example of when they give a `true` value:
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| Method | Description | Example |
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| ------ | ------------ | ------- |
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| == | equal | 4 == 4 |
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| != | not equal | 5 != 4 |
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## Combined comparison operator
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The combined comparison operator (sometimes called spaceship operator) is a special comparison operator.
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It is special in the sense that it doesn't return a truthy or falsey value but it returns a number.
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It is written as `<=>` and it is used to compare 2 values.
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It will return `1` if the left value is greater than the right value, `-1` if the left value is less than the right value, and `0` if the values are equal.
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```ruby
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x = 5
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1 <=> 2 # => -1
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2 <=> 2 # => 0
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3 <=> 2 # => 1
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```
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if x == 5
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# Execute logic if x equals 5
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elsif x > 7
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# Execute logic if x greater than 7
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else
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# Execute logic in all other cases
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## If statement
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The [`if`][if] statement is used to check if a given condition is "truthy" or "falsey".
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If the condition is truthy then the code inside the if statement will run.
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An `if` statement ends with the `end` keyword.
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```ruby
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value = 1
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if value == 1
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"1 is equal to 1"
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end
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# => "1 is equal to 1"
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if value > 2
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"1 is greater than 2"
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end
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# => nil
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```
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Sometimes you want to execute a statement (or statements) if a condition is _not_ true, for situations like that, Ruby implements the `unless` keyword:
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## Unless statement
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The `unless`unless statement works very similarly to the `if` statement but it will run the code inside the `unless` statement if the condition is falsey.
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```ruby
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x = 4
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unless x == 5
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# Execute logic if x does not equal 5
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value = 1
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unless value == 1
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"1 is not equal to 1"
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end
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# => nil
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unless value > 2
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"1 is not greater than 2"
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end
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# => "1 is not greater than 2"
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```
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## Else statement
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The `else` statement can be used in conjunction with the `if` and `unless` statements.
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The `else` statement will be executed if the `if` branch or the `unless` branch is not executed.
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```ruby
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value = 1
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if value == 1
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"1 is equal to 1"
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else
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# Execute logic if x == 5
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"1 is not equal to 1"
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end
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# => "1 is equal to 1"
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unless value < 2
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"1 is not greater than 2"
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end
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# => "1 is greater than 2"
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```
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If you want to execute different code depending on the value of a variable, Ruby's `case` statement might come useful:
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## "Cascading-if" statements
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The `elsif` statement can be used in conjunction with the if statement.
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The `elsif` statement will be executed if the if branch is not executed and the condition of the elsif statement is truthy.
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Elsif statements can be chained together and the first truthy condition will be executed.
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There can also be an else statement at the end of the if statement which will run if non of the earlier statement has been true.
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```ruby
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y = 5
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case y
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when 3
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# Execute logic if y equals 3
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when 5
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# Execute logic if y equals 5
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value = 1
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if value != 1
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"1 is not equal to 1"
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elsif value > 2
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"1 is greater than 2"
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else
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# Execute logic in all other cases
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"1 is not equal to 1 and 1 is not greater than 2"
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end
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# => "1 is not equal to 1 and 1 is not greater than 2"
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```
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The same problem can sometimes be solved using different types of conditional statements, sometimes one might be more suited for the problem than the other. It's a good idea to stop for a moment and also consider the other two options when using any of the three conditional statements.
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## if and unless as suffix
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The if and unless statement can also be used as a [suffix][if-as-suffix], this is useful when you want to run a single line of code if a condition is true.
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It is done by putting the if or unless statement after the code that you want to run.
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```ruby
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value = 1
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"1 is equal to 1" if value == 1
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# => 1 is equal to 1
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"1 is not equal to 1" unless value == 1
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# => nil
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```
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[arithmetic-operators]: https://www.tutorialspoint.com/ruby/ruby_operators.htm
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[comparison-operators]: https://www.w3resource.com/ruby/ruby-comparison-operators.php
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[if-else-unless]: https://www.w3resource.com/ruby/ruby-if-else-unless.php
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[integer-ruby]: https://ruby-doc.org/core-2.7.1/Integer.html
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[float-ruby]: https://ruby-doc.org/core-2.7.1/Float.html
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[if]: https://www.rubyguides.com/ruby-tutorial/ruby-if-else/

‎concepts/conditionals/introduction.md

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@@ -1,40 +1,111 @@
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# Introduction
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# Conditionals
22

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An `if` statement can be used to conditionally execute code:
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Ruby has what is known as flow control expressions, these are used to control the way the program will run and they take a truthy or falsey value.
4+
There are operators that can be used to create truthy or falsey values, these are known as [comparison operators][comparison-operators].
5+
6+
There are two main control expressions that are used to control which code will run and which will not.
7+
Also known as which given branch will run.
8+
9+
Those two are: `if` and the `unless` expression.
10+
11+
## Comparison operators
12+
13+
[Comparison operators][comparison-operators] are used to compare values and return a `true` or `false` value.
14+
The following operators require two values to be compared of the same type.
15+
If the values are not of the same type then the compiler will throw an error.
16+
Here is a list of the operators and an example of when they give a `true` value:
17+
18+
| Method | Description | Example |
19+
| ------ | --------------------- | ------- |
20+
| < | less than | 5 < 4 |
21+
| <= | less than or equal | 4 <= 4 |
22+
| > | greater than | 3 > 1 |
23+
| >= | greater than or equal | 2 >= 2 |
24+
25+
The equal and not equal operators can be used to compare any type of value contrary to the operators already mentioned.
26+
The `==` operator is used to check if two values are equal, and that includes checking the type of the value.
27+
The `!=` works the same way but it will return `true` if the values are not equal and `false` if they are equal.
28+
Here is a list of the equal and not equal operators and an example of when they give a `true` value:
29+
30+
| Method | Description | Example |
31+
| ------ | ------------ | ------- |
32+
| == | equal | 4 == 4 |
33+
| != | not equal | 5 != 4 |
34+
35+
## If statement
36+
37+
The [`if`][if] statement is used to check if a given condition is "truthy" or "falsey".
38+
If the condition is truthy then the code inside the if statement will run.
39+
An `if` statement ends with the `end` keyword.
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```ruby
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x = 5
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value = 1
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if value == 1
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"1 is equal to 1"
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end
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# => "1 is equal to 1"
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if x == 5
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# Execute logic if x equals 5
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elsif x > 7
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# Execute logic if x greater than 7
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else
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# Execute logic in all other cases
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if value > 2
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"1 is greater than 2"
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end
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# => nil
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```
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## Unless statement
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The `unless`unless statement works very similarly to the `if` statement but it will run the code inside the `unless` statement if the condition is falsey.
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```ruby
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value = 1
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unless value == 1
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"1 is not equal to 1"
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end
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# => nil
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unless value > 2
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"1 is not greater than 2"
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end
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# => "1 is not greater than 2"
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```
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Sometimes you want to execute a statement (or statements) if a condition is _not_ true, for situations like that, Ruby implements the `unless` keyword:
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## Else statement
72+
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The `else` statement can be used in conjunction with the `if` and `unless` statements.
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The `else` statement will be executed if the `if` branch or the `unless` branch is not executed.
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```ruby
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x = 4
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unless x == 5
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# Execute logic if x does not equal 5
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value = 1
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if value == 1
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"1 is equal to 1"
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else
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# Execute logic if x == 5
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"1 is not equal to 1"
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end
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# => "1 is equal to 1"
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unless value < 2
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"1 is not greater than 2"
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end
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# => "1 is greater than 2"
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```
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If you want to execute different code depending on the value of a variable, Ruby's `case` statement might come useful:
91+
## "Cascading-if" statements
92+
93+
The `elsif` statement can be used in conjunction with the if statement.
94+
The `elsif` statement will be executed if the if branch is not executed and the condition of the elsif statement is truthy.
95+
Elsif statements can be chained together and the first truthy condition will be executed.
96+
There can also be an else statement at the end of the if statement which will run if non of the earlier statement has been true.
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```ruby
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y = 5
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case y
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when 3
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# Execute logic if y equals 3
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when 5
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# Execute logic if y equals 5
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value = 1
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if value != 1
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"1 is not equal to 1"
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elsif value > 2
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"1 is greater than 2"
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else
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# Execute logic in all other cases
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"1 is not equal to 1 and 1 is not greater than 2"
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end
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# => "1 is not equal to 1 and 1 is not greater than 2"
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```
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[comparison-operators]: https://www.w3resource.com/ruby/ruby-comparison-operators.php
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[if]: https://www.rubyguides.com/ruby-tutorial/ruby-if-else/

‎concepts/conditionals/links.json

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[
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{
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"url": "https://ruby-doc.org/core-2.7.1/Integer.html",
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"description": "integer-ruby"
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},
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{
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"url": "https://ruby-doc.org/core-2.7.1/Float.html",
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"description": "float-ruby"
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},
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{
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"url": "https://www.tutorialspoint.com/ruby/ruby_operators.htm",
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"description": "arithmetic-operators"
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},
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{
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"url": "https://www.w3resource.com/ruby/ruby-comparison-operators.php",
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"description": "comparison-operators"
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},
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{
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"url": "https://www.rubyguides.com/ruby-tutorial/ruby-if-else/",
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"description": "Ruby Guides: The Beginner's Guide to Ruby If & Else Statements"
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}
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]

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