The Assignment Operator in Php

You have met the assignment operator each time we have initialized a variable. It
consists of the single character =. The assignment operator takes the value of its
right-hand operand and assigns it to its left-hand operand:
$name ="matt";
The variable $name now contains the string "matt". Interestingly, this construct is
an expression. It might look at first glance that the assignment operator simply
changes the variable $name without producing a value, but in fact, a statement that
uses the assignment operator always resolves to a copy of the value of the right
operand. Thus
print ( $name = "matt" );
prints the string "matt" to the browser in addition to assigning "matt" to $name.
Arithmetic Operators