TRUE represents the
NULL, which can be thought of as “nothing”
and is output as the empty string.
The simplest forms of expressions are literals (such as numbers and strings) and variables, which simply evaluate to themselves.
The difference between unary, binary, and ternary operators is the number of operands each requires (one, two, and three, respectively).
The best way to force your own operator precedence is to place parentheses around subexpressions to which you wish to give high precedence.
Operator associativity refers to the direction of processing (left to right or right to left).
You use the identity operator when you wish to bypass PHP’s automatic operand type changing (also called type casting).
The three conditional statement types are
switch, and the
To skip the current iteration of a loop and move on to the next
one, use a
are more powerful than
because they support two additional parameters to control the loop
Most conditional expressions in
while statements are literal (or Boolean)
and therefore trigger execution when they evaluate to
TRUE. Numeric expressions trigger execution
when they evaluate to a nonzero value. String expressions trigger
execution when they evaluate to a nonempty string. A
NULL value is evaluated as false and
therefore does not trigger execution.