Name: and

Type: operator

Syntax: <leftValue> and <rightValue>

Summary:

Allows the construction of compound <boolean> expressions, which <evaluate> to true

if both <operand|operands> are true, false otherwise.

Introduced: 1.0

OS: mac, windows, linux, ios, android, html5

Platforms: desktop, server, mobile

Example:

put (1 > 0) and (1 = 0)

-- evaluates to false

Example:

put (1 > 0) and (1 = 1) and (0 = 0)

-- evaluates to true

Example:

local myCount

if the shiftKey is down and myCount > 1 then exit mouseUp

Parameters:

leftValue (bool):

leftValue is true or false, or an expression that evaluates to

true or false.

rightValue (bool):

rightValue is true or false, or an expression that evaluates to

true or false.

Description:

Use the <and> <operator> to combine two or more <logical>

<value(glossary)|values> into a compound <boolean> <expression>.

If <leftValue> is false or <rightValue> is false, or if both <leftValue> and

<rightValue> are false, then the <and> <operation> <evaluate|evaluates> to

false. If <leftValue> and <rightValue> are both true, the <expression> `leftValue

and rightValue` <evaluate|evaluates> to true. In an <expression> with more

than two <operand|operands>, there is an implicit grouping of the first pair,

so that the first pair is <evaluate|evaluated> first, then subsequent values

are <evaluate|evaluated>. If any of the operands <evaluate|evaluates> to false,

the entire <expression> <evaluate|evaluates> to false. You can combine

the <logical> <operator|operators> <and>, <or>, and <not>

in an <expression>.

>*Note:* LiveCode uses what is known as "short-circuit evaluation" for

> <logical> <operator(glossary)|operators>. This means that <leftValue> is

> <evaluate|evaluated> first. If <leftValue> is false, the <expression>

> `leftValue and rightValue` is false regardless of what <rightValue> is (because the

> <expression> <evaluate|evaluates> to false unless both the values are

> true). In this case, LiveCode does not <evaluate> <rightValue>, since

> doing so is not necessary to determine the <value(function)> of <leftValue>

> or <rightValue>. For example, evaluating the <expression> `asin(2)` normally

> causes an <execution error> (because 2 is not a legal <argument> for the

> arc sine function), but <evaluate|evaluating> the <expression>

> `(1 = 0) and (asin(2) = 1)` does not cause an error: since `(1 = 0)` is

> always false, the whole statement is always false and LiveCode never tries

> to <evaluate> the <asin> <function>.

References: argument (glossary), asin (function), bitAnd (operator),

boolean (glossary), evaluate (glossary), execution error (glossary),

expression (glossary), false (constant), function (glossary),

logical (glossary), not (operator), operand (glossary),

operation (glossary), operator (glossary), or (operator),

true (constant), value (function), value (glossary)

Tags: math