Logical Operators

When working with comparative operators, it is incredibly useful to be able to quickly and concisely check the comparisons meet certain conditions.

Execution Order

Logical operators like and and or are evaluated after all other comparisons or expressions on either side of the operator are evaluated. This means that, in an expression such as 10 == 10 and true, the comparison 10 == 10 is evaluated first, returning true. Then, the logical and operation is performed.

AND

A logical and statement will evaluate both of its operands, and if they are both true, then it will return true, otherwise it will return false. The way you write an and operator in osl is simply a lowercase and.

You can see the truth table below

A	B	A and B
true	true	true
true	false	false
false	true	false
false	false	false

log true and true
// this returns true

log 10 == 10 and true
// this returns true
// 10 == 10 is true
// true is true
// therefore both sides are true and the overall operator returns true

OR

A logical or statement will evaluate both of its operands, and if either or both of them are true, then it will return true, otherwise it will return false. The way you write an or operator in osl is simply a lowercase or.

You can see the truth table below

A	B	A or B
true	true	true
true	false	true
false	true	true
false	false	false

log true or false
// this returns true

NOR

A logical nor statement will evaluate both of its operands, and if neither of them are true, then it will return true, otherwise it will return false. The way you write a nor operator in osl is simply a lowercase nor.

You can see the truth table below

A	B	A nor B
true	true	false
true	false	false
false	true	false
false	false	true

log true nor false
// this returns false

XOR

A logical xor statement will evaluate both of its operands, and if both are true or both are false, then it will return false, otherwise it will return true. The way you write a xor operator in osl is simply a lowercase xor.

You can see the truth table below

A	B	A xor B
true	true	false
true	false	true
false	true	true
false	false	false

log true xor false
// this returns true

XNOR

A logical xnor statement will evaluate both of its operands, and if both of them are true or both of them are false, then it will return true, otherwise it will return false. The way you write a xnor operator in osl is simply a lowercase xnor.

You can see the truth table below

A	B	A xnor B
true	true	true
true	false	false
false	true	false
false	false	true

log true xnor false
// this returns false

NAND

A logical nand statement will evaluate both of its operands, and if both of them aren't true, then it will return true, otherwise it will return false. The way you write a nand operator in osl is simply a lowercase nand.

You can see the truth table below

A	B	A nand B
true	true	false
true	false	true
false	true	true
false	false	true

log true nand false
// this returns true
// nand is literally "not and" so it will return the opposite of an and statement

NOT

The NOT statement negates the truth value of its operand. In the context of osl, you can apply it using an exclamation mark (!) before a value or group of values. Here's how it works:

• !true evaluates to false.

• !false evaluates to true.

In osl, you can also use the ! operator in conjunction with logical operators to achieve similar effects. For instance, !(false and true) evaluates to true since the AND operation between false and true is false, and the NOT operation negates it.

log !true
// false

log !(true and true)
// false