Boolean Operators

- "not"-Operator
`!`

- "and"-Operator
`&&`

- "or"-Operator
`||`

`!`

We use `!`

to negate/switch a boolean value

```
!true # false
!false # true
```

```
payment_received = false
if !payment_received
send_payment_reminder_email
end
```

`&&`

We use `&&`

to combine two or more boolean values with the "and" rule (aka *conjuction*)

```
true && true # true
true && false # false
false && true # false
false && false # false
```

(See also https://en.wikipedia.org/wiki/Logical_conjunction)

```
weather = "sunny"
temperature = 27 # celsius
if weather == "sunny" && temperature > 20
puts "You may wear sandals! π‘"
end
```

We can combine as many booleans as we want.

```
if condition_1 && condition_2 && condition_3 # ...
puts "This happens only if all conditions were true"
end
```

Remember: Only if **all** booleans are ** true**, the final result is

`true`

`||`

We use `||`

to combine two boolean values with the "or" rule (aka *disjunction*)

```
true || true # true
true || false # true
false || true # true
false || false # false
```

(See also https://en.wikipedia.org/wiki/Logical_disjunction)

```
hour_of_day = 15 # valid: 0 - 23
if hour_of_day < 6 || hour_of_day > 22
puts "You really should go to sleep! ποΈ"
else
puts "Enjoy your day! π"
end
```

Again, we can combine as many booleans as we want.

```
if condition_1 || condition_2 || condition_3 # ...
puts "This happens only if 1 or more conditions were true"
end
```

Remember: If **at least one** boolean is ** true**, the final result is

`true`

Again, we can combine as many booleans as we want.

```
if condition_1 || condition_2 || condition_3 # ...
puts "This happens only if 1 or more conditions were true"
end
```

Remember: If **at least one** boolean is ** true**, the final result is

`true`

We use parentheses `()`

to group boolean results.

```
travel_mode = 'bicycle' # walking πΆββοΈ or bicycle π΄ββοΈ
distance = 1500 # meters
if (distance > 5000) || (distance > 1000 && travel_mode == 'walking')
puts "You better take something to drink π§ with you".
end
```

What **questions** do you have?