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harlowe:boolean [2017/06/19 02:17]
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harlowe:boolean [2017/10/09 20:39]
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-Computers can perform more than just mathematical tasks - they are also virtuosos in classical logic. Much as how 
-arithmetic involves manipulating [[harlowe:​number|number]] with addition, multiplication and such, logic involves manipulating the 
-values ''​%%true%%''​ and ''​%%false%%''​ using its own operators. Those are not text [[harlowe:​string|string]] - they are values as fundamental as 
-the natural numbers. In computer science, they are both called //​Booleans//,​ after the 19th century mathematician 
-George Boole. 
  
-''​%%is%%''​ is a logical operator. Just as + adds the two numbers on each side of it, ''​%%is%%''​ compares two values on each 
-side and evaluates to ''​%%true%%''​ or ''​%%false%%''​ depending on whether they'​re identical. It works equally well with strings, 
-numbers, [[harlowe:​Array|Array]],​ and anything else, but beware - the string ''​%%"​2"​%%''​ is not equal to the number 2. 
- 
-There are several other logical operators available. 
-^Operator ​       ^ Purpose ^ Example ^ 
-| ''​%%is%%''​ | Evaluates to ''​%%true%%''​ if both sides are equal, otherwise ''​%%false%%''​. | ''​%%$bullets is 5%%''​ 
-| ''​%%is not%%''​ | Evaluates to ''​%%true%%''​ if both sides are not equal. | ''​%%$friends is not $enemies%%''​ 
-| ''​%%contains%%''​ | Evaluates to ''​%%true%%''​ if the left side contains the right side. | ''​%%"​Fear"​ contains "​ear"​%%''​ 
-| ''​%%is in%%''​ | Evaluates to ''​%%true%%''​ if the right side contains the left side. | ''​%%"​ugh"​ is in "​Through"​%%''​ 
-| ''​%%>​%%''​ | Evaluates to ''​%%true%%''​ if the left side is greater than the right side. | ''​%%$money > 3.75%%''​ 
-| ''​%%>​=%%''​ | Evaluates to ''​%%true%%''​ if the left side is greater than or equal to the right side. | ''​%%$apples >= $carrots + 5%%''​ 
-| ''​%%<​%%''​ | Evaluates to ''​%%true%%''​ if the left side is less than the right side. | ''​%%$shoes < $people * 2%%''​ 
-| ''​%%<​=%%''​ | Evaluates to ''​%%true%%''​ if the left side is less than or equal to the right side. | ''​%%65 <= $age%%''​ 
-| ''​%%and%%''​ | Evaluates to ''​%%true%%''​ if both sides evaluates to ''​%%true%%''​. | ''​%%$hasFriends and $hasFamily%%''​ 
-| ''​%%or%%''​ | Evaluates to ''​%%true%%''​ if either side is ''​%%true%%''​. | ''​%%$fruit or $vegetable%%''​ 
-| ''​%%not%%''​ | Flips a ''​%%true%%''​ value to a ''​%%false%%''​ value, and vice versa. | ''​%%not $stabbed%%''​ 
- 
- 
-Conditions can quickly become complicated. The best way to keep things straight is to use parentheses to 
-group things. 
harlowe/boolean.txt ยท Last modified: 2017/10/09 20:39 (external edit)