Programming PHP

Bitwise-OR-equals (|=)
Performs a bitwise OR on the value of the lefthand operand and the righthand
operand, then assigns the result to the lefthand operand.
Concatenate-equals (.=)
Concatenates the righthand operand to the value of the lefthand operand, then
assigns the result to the lefthand operand.
Miscellaneous Operators
The remaining PHP operators are for error suppression, executing an external command,
and selecting values:
Error suppression (@)
Some operators or functions can generate error messages. The error suppression
operator, discussed in full in Chapter 13, is used to prevent these messages from
being created.
Execution (`...`)
The backtick operator executes the string contained between the backticks as a
shell command and returns the output. For example:
$listing = `ls –ls /tmp`;
echo $listing;
Conditional (?:)
The conditional operator is, depending on the code you look at, either the most
overused or most underused operator. It is the only ternary (three-operand)
operator and is therefore sometimes just called the ternary operator.
The conditional operator evaluates the expression before the ?. If the expression
is true, the operator returns the value of the expression between the ? and :;
otherwise, the operator returns the value of the expression after the :. For
instance: