B.4 Assignment

Scalar variables are assigned scalar values with an assignment statement. For instance:

$thousand = 1000;

assigns the integer 1,000, a scalar value, to the scalar variable $thousand.

The assignment statement looks like an equal sign from elementary mathematics, but its meaning is different. The assignment statement is an instruction, not an assertion. It doesn't mean "$thousand equals 1,000." It means "store the scalar value 1,000 into the scalar variable $thousand". However, after the statement, the value of the scalar variable $thousand is, indeed, equal to 1000.

You can assign values to several scalar variables by surrounding variables and values in parentheses and separating them by commas, thus making lists:

($one, $two, $three) = ( 1, 2, 3);

There are several assignment operators besides = that are shorthand for longer expressions. For instance, $a += $b is equivalent to $a = $a + $b. Table B-1 is a complete list (it includes several operators that aren't covered in this book).

Table B-1. Assignment operator shorthands

Example of operator	Equivalent
$a += $b	$a = $a + $b (addition)
$a -= $b	$a = $a - $b (subtraction)
$a *= $b	$a = $a * $b (multiplication)
$a /= $b	$a = $a / $b (division)
$a **= $b	$a = $a ** $b (exponentiation)
$a %= $b	$a = $a % $b (remainder of $a / $b)
$a x= $b	$a = $a x $b (string $a repeated $b times)
$a &= $b	$a = $a & $b (bitwise AND)
$a |= $b	$a = $a | $b (bitwise OR)
$a ^= $b	$a = $a ^ $b (bitwise XOR)
$a >>= $b	$a = $a >> $b ($a shift $b bits)
$a <<= $b	$a = $a >> $b ($a shift $b bits to left)
$a &&= $b	$a = $a && $b (logical AND)
$a ||= $b	$a = $a || $b (logical OR)
$a .= $b	$a = $a . $b (append string $b to $a)