Any PHP script is built out of a series of statements. A
statement can be an assignment, a function call, a loop, a
conditional statement of even a statement that does nothing
(an empty statement). Statements usually end with a
semicolon. In addition, statements can be grouped into a
statement-group by encapsulating a group of statements with
curly braces. A statement-group is a statement by itself as
well. The various statement types are described in this
chapter.
The if construct is one of
the most important features of many languages, PHP
included. It allows for conditional execution of code
fragments. PHP features an if
structure that is similar to that of C:
As described in
the section about expressions,
expr is evaluated to its Boolean value. If expr evaluates to TRUE, PHP will execute statement, and if it
evaluates to FALSE - it'll
ignore it. More information about what values evaluate to
FALSE can be found in the
'Converting to boolean' section.
The following example would display a is bigger than b if $a is bigger than $b:
Often you'd want to have more than one statement to be
executed conditionally. Of course, there's no need to wrap
each statement with an if clause.
Instead, you can group several statements into a statement
group. For example, this code would display a is bigger than b if $a is bigger than $b, and would then assign the
value of $a into $b:
If statements can be nested
indefinitely within other if
statements, which provides you with complete flexibility
for conditional execution of the various parts of your
program.