Gamma: Version 4.0
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# Increment and Decrement Operators

Increment and decrement operators -- (`++`, `--`)

## Syntax

    ++symbol
    symbol++
    --symbol
    symbol__

## Arguments

`symbol`

  A symbol whose value is a number.

## Returns

The value of the symbol plus or minus one.

## Description

These operators perform auto-increments or decrements on numeric symbols. When the `++` is placed before a symbol, it performs a pre-increment, where the value is incremented and the result is the symbol's value + 1. When `++` is placed after a symbol, it performs a post-increment. Here the result of the operation is the value of the symbol prior to being incremented. The `--` operator works in the same way. These operators only take symbols as arguments. It is not possible to auto-increment or decrement an array element, list element, or instance variable.

## Examples

        Gamma> a = 5;
        5
        Gamma> ++ a;
        6
        Gamma> a;
        6
        Gamma> a ++;
        6
        Gamma> a;
        7
        Gamma> a = 5;
        5
        Gamma> -- a;
        4
        Gamma> a;
        4
        Gamma> a --;
        4
        Gamma> a;
        3
        Gamma>

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