$counter = $counter + 1;This code adds 1 to the value currently stored in the
$counter variable and then saves the result back in the $counter variable. PHP provides a handy shortcut method for doing this:
$counter += 1;This code accomplishes the exact same thing, but in a shorter form. You can use the same shortcut with any type of arithmetic operator:
$total *= 1.10;This example multiplies the value stored in the
$total variable by 1.10 and stores the result back in the $total variable. You can also use variables on the right side of the assignment operation:
$total *= $taxrate;This is the same as typing the following:
$total = $total * $taxrate;That can really save some typing for you!
Two other types of arithmetic shortcuts are the incrementor and decrementor operators. The incrementor operator adds 1 to a variable's value:
$counter++;The decrementor operator subtracts 1 from the variable’s value:
$counter--;Now that’s really saving some typing!
The arithmetic shortcut operators assume there’s already a value stored in the variable before the operation. If there isn’t, PHP will generate a warning message, telling you that it assumes the initial value is 0. It’s always a good idea to initialize a variable to a known value before trying to use it in any arithmetic operations.