This is a collection of questions that come up now and then about syntax in PHP. This is also a Community Wiki, so everyone is invited to participate in maintaining this list.
This question shouldn't be used as a dupe target for closing questions. Use actual questions linked here as dupe targets instead.
It used to be hard to find questions about operators and other syntax tokens.¹
The main idea is to have links to existing questions on Stack Overflow, so it's easier for us to reference them, and not to copy over content from the PHP Manual.
Note: Since January 2013, Stack Overflow does support special characters. Just surround the search terms by quotes, e.g. [php] "==" vs "==="
If you have been pointed here by someone because you have asked such a question, please find the particular syntax below. The linked pages to the PHP manual along with the linked questions will likely answer your question then. If so, you are encouraged to upvote the answer. This list is not meant as a substitute for the help others provide.
If your particular token is not listed below, you might find it in the List of Parser Tokens.
& Bitwise Operators or References
=& References
Double question mark
?? Null Coalesce Operator (since PHP 7)
A question mark followed by a type declaration
?string
?int
?array
?bool
?float Nullable type declaration (since PHP 7.1)
?-> question mark followed by object operator is a NullSafe Operator (since PHP 8.0)
: Alternative syntax for control structures, Ternary Operator, Return Type Declaration
=> Arrays
<=> Comparison Operators (since PHP 7.0)
+ Arithmetic Operators, Array Operators
+= and -= Assignment Operators
++ and -- Incrementing/Decrementing Operators
<?= Short Open Tags
[] Arrays (short syntax since PHP 5.4)
$var = [] empty array.. Double-dot character range
... Argument unpacking (since PHP 5.6)
** Exponentiation (since PHP 5.6)
# One-line shell-style comment
#[] Attributes (since PHP 8)
Incrementing / Decrementing Operators
++ increment operator
-- decrement operator
Example Name Effect
---------------------------------------------------------------------
++$a Pre-increment Increments $a by one, then returns $a.
$a++ Post-increment Returns $a, then increments $a by one.
--$a Pre-decrement Decrements $a by one, then returns $a.
$a-- Post-decrement Returns $a, then decrements $a by one.
These can go before or after the variable.
If put before the variable, the increment/decrement operation is done to the variable first then the result is returned. If put after the variable, the variable is first returned, then the increment/decrement operation is done.
For example:
$apples = 10;
for ($i = 0; $i < 10; ++$i) {
echo 'I have ' . $apples-- . " apples. I just ate one.\n";
}
In the case above ++$i is used, since it is faster. $i++ would have the same results.
Pre-increment is a little bit faster because it really increments the variable and after that 'returns' the result. Post-increment creates a special variable, copies there the value of the first variable and only after the first variable is used, replaces its value with second's.
However, you must use $apples--, since first, you want to display the current number of apples, and then you want to subtract one from it.
You can also increment letters in PHP:
$i = "a";
while ($i < "c") {
echo $i++;
}
Once z is reached aa is next, and so on.
Note that character variables can be incremented but not decremented and even so only plain ASCII characters (a-z and A-Z) are supported.
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