15.1 Arithmetic Operators

As in most computer languages, multiplication and division take precedence over addition and subtraction (in the absence of parentheses). So, for example:

3 + 4 * 2 -- 11
3 * 4 + 2 -- 14

An operand that is a list consisting of one number will be coerced to a number. An operand that is a string, or a list consisting of one string, will be coerced to a number if possible.

Syntax

Description

The addition operator is not overloaded to perform string concatenation; see on the ampersand operator (&) later in this chapter. A date plus an integer yields date increased by integer seconds.

The result is an integer if the first operand is an integer and if the second operand can be coerced to an integer without loss of information. Otherwise, the result is a real.

Syntax

Description

A date minus an integer yields date decreased by integer seconds. A date minus a date yields an integer, the number of seconds between them. For two numbers, see on addition (+).

Unary negation has very high precedence.

Example

-3 ^ 2 -- 9

Syntax

Description

For the class of the result, see on addition (+).

Syntax

Description

Both numbers are treated as reals, and the result is a real.

Syntax

Description

Both numbers are treated as reals; the first is divided by the second, and the result is coerced to an integer by throwing away its fractional part. Notice that this is not the same as AppleScript's normal real-to-integer coercion behavior.

Example

4 div 5 -- 0
(4 / 5) as integer -- 1

Syntax

Description

The first operand is divided by the absolute value of the second and the remainder is returned. For the class of the result, see on addition (+).

Syntax

Description

Raises the first number to the power of the second. The result is a real.

Do not blame AppleScript for the phenomena inherent in doing floating-point arithmetic in any language on any computer. It is the nature of computer numerics that most values can only be approximated. Modern processors are extraordinarily clever about compensating, but rounding operations can easily expose the truth:

2.32 * 100.0 div 1 -- 231

Similarly, there may be situations where instead of comparing two values for absolute equality you will do better to test whether the difference between them lies within some acceptable small epsilon.