The **auto-increment** and **auto-decrement** operators in Perl allow us to *increment* or  *decrement* the value of an integer by `1`.

These are **unary** operators and take just one operand.

The following are the operator representations:

- Auto-increment : `++`
- Auto-decrement : `--`

There are two variations of each of these operators: pre-increment/post-increment and pre-decrement/post-decrement.


## Pre-increment and pre-decrement

If we append the auto-increment or auto-decrement operators *before* the variable, the operation is termed as **pre-increment** or **pre-decrement** depending on the operator used.

```perl
++$x # pre-increment
--$x # pre-decrement
```

In these operations, the value is updated instantly. Let's look at an example:





# taking a variable
$x = 10;
$test = ++$x;

print "The value of test (pre-inc) is: $test\n";
print "The value of x is: $x\n";

$y = 10;
$test2 = --$y;

print "The value of test (pre-dec) is: $test2\n";
print "The value of y is: $y\n";


In the above example, we define the variables `x` and `y`. The variables are pre-incremented and pre-decremented, respectively, and then associated with a `test` variable.

The variables are incremented/decremented at the time of association with the `test` variable, i.e., instantly.

This is why the `test` variables, `x`, and `y` all contain the same values.

## Post-increment and post-decrement

If we append the auto-increment or auto-decrement operators *after* the variable, the operation is termed as **post-increment** or **post-decrement** depending on the operator used.

```perl
$x++ # post increment
$x-- # post decrement
```
In these operations, the value is stored in a temporary variable and updated after the execution of the current statement. Let's look at an example:


# taking a variable
$x = 10;
$test = $x++;

print "The value of test (post-inc) is: $test\n";
print "The value of x is: $x\n";

$y = 10;
$test2 = $y--;

print "The value of test (post-dec) is: $test2\n";
print "The value of y is: $y\n";


In the above example, we use the post-increment and post-decrement operators. As a result, the values of `x` and `y` are updated after the execution of the assignment statements.

Therefore, the `test` variables contain the previous values of `x` and `y`, while the variables themselves are updated.

What are auto-increment and auto-decrement operators in Perl?

Pre-increment and pre-decrement

Post-increment and post-decrement