Specifications

Combination Assignment Operators

In addition to the simple assignment, there is a set of combined assignment operators. Each of

these is a shorthand way of doing another operation on a variable and assigning the result back

to that variable. For example

$a += 5;

This is equivalent to writing

$a = $a + 5;

Combined assignment operators exist for each of the arithmetic operators and for the string

concatenation operator.

A summary of all the combined assignment operators and their effects is shown in Table 1.2.

TABLE 1.2 PHP’s Combined Assignment Operators

Operator Use Equivalent to

+= $a += $b $a = $a + $b

-= $a -= $b $a = $a - $b

*= $a *= $b $a = $a * $b

/= $a /= $b $a = $a / $b

%= $a %= $b $a = $a % $b

.= $a .= $b $a = $a . $b

Pre- and Post-Increment and Decrement

The pre- and post- increment (++) and decrement (--) operators are similar to the += and -=

operators, but with a couple of twists.

All the increment operators have two effects—they increment and assign a value. Consider the

following:

$a=4;

echo ++$a;

The second line uses the pre-increment operator, so called because the ++ appears before the

$a. This has the effect of first, incrementing $a by 1, and second, returning the incremented

value. In this case, $a is incremented to 5 and then the value 5 is returned and printed. The

value of this whole expression is 5. (Notice that the actual value stored in $a is changed: We

are not just returning $a + 1.)

Using PHP

ART I

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