The basic assignment operator is "=". Your first
inclination might be to think of this as "equal to". Don't.
It really means that the the left operand gets set to the
value of the expression on the rights (that is, "gets set
to").
The value of an assignment expression is the value
assigned. That is, the value of "$a = 3" is 3. This allows
you to do some tricky things:
In addition to the basic assignment operator, there are
"combined operators" for all of the binary arithmetic and
string operators that allow you to use a value in an
expression and then set its value to the result of that
expression. For example:
$a = 3; $a += 5; // sets $a to 8, as if we had said: $a = $a + 5; $b = "Hello "; $b .= "There!"; // sets $b to "Hello There!", just like $b = $b . "There!"; |
Note that the assignment copies the original variable to
the new one (assignment by value), so changes to one will not
affect the other. This may also have relevance if you need to
copy something like a large array inside a tight loop. PHP 4
supports assignment by reference, using the $var = $othervar; syntax, but this
is not possible in PHP 3. 'Assignment by reference' means
that both variables end up pointing at the same data, and
nothing is copied anywhere. To learn more about references,
please read References
explained.