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-- (decrement) operator

The left-associative, unary -- operators decrement their operand; they differ in whether the result is assigned before or after the decrement.

Usage

Postfix -- has the operator after the operand:

variable Integer num = 1;
num--;

Prefix -- puts the operator before the operand:

variable Integer num = 1;
--num;

Description

Both operators decrement their operand by one. The difference is that the prefix operator updates its operand and evaluates to the updated value. The postfix operator, in contrast, decrements its operand but evaluates to the value of the operand before the decrement.

Definition

The prefix -- is defined as:

rhs = rhs.predecessor

The postfix -- is defined as:

let (x = lhs, _ = lhs = lhs.predecessor) x

See the language specification for more details.

Polymorphism

The -- operator is polymorphic. The meaning of -- depends on the Ordinal interface.

Type

The result type of the -- operator is the same as the Ordinal type of its operand.

See also