what does the the -= operator do

June 7, 2009
Posted by Clinton Montague

what does the the -= operator do

The -= operator is a simplified way of writing I want to decrease the variable by a certain value. It’s called the subtraction-assignment operator.

Examples

$i = 10;
$i-=1;
echo $i; // outputs 9;
 
$i = 10;
$i-=5;
echo $i; // outputs 5
 
$i=10;
$i-= -10;
echo $i; // output 20 (since 10 - (-10) is the same as 10+10;
 
$i=10;
$i-=$i;
echo $i; // output 0;