Types
This example provides a great opportunity to emphasize the newline issue as it relates to HTML rendering.
<?php
$a_bool = TRUE; // a boolean
$a_str = "foo"; // a string
$a_str2 = 'foo'; // a string
$an_int = 12; // an integer
echo 'a_bool is a ';
echo gettype($a_bool);
echo '<br>';
echo 'a_str is a ';
echo gettype($a_str); // prints out: string
echo '<br>';
echo 'an_int is a ';
echo gettype($an_int); // prints out: string
echo '<br>';
// If this is an integer, increment it by four
if (is_int($an_int)) {
$an_int += 4;
echo "<br>integer: $an_int";
}
// If $bool is a string, print it out
// (does not print out anything)
if (is_string($a_bool)) {
echo "String: $a_bool";
}
?>
Introduction
PHP supports eight primitive types.
Four scalar types:
Two compound types:
And finally two special types:
This manual also introduces some pseudo-types for readability reasons:
And the pseudo-variable $... .
Some references to the type "double" may remain in the manual. Consider double the same as float; the two names exist only for historic reasons.
The type of a variable is not usually set by the programmer; rather, it is decided at runtime by PHP depending on the context in which that variable is used.
Note: To check the type and value of an expression, use the var_dump() function. To get a human-readable representation of a type for debugging, use the gettype() function. To check for a certain type, do not use gettype(), but rather the is_type functions. Some examples:
<?php
$a_bool = TRUE; // a boolean
$a_str = "foo"; // a string
$a_str2 = 'foo'; // a string
$an_int = 12; // an integer
echo gettype($a_bool); // prints out: boolean
echo gettype($a_str); // prints out: string
// If this is an integer, increment it by four
if (is_int($an_int)) {
$an_int += 4;
}
// If $bool is a string, print it out
// (does not print out anything)
if (is_string($a_bool)) {
echo "String: $a_bool";
}
?>
To forcibly convert a variable to a certain type, either cast the variable or use the settype() function on it.
Note that a variable may be evaluated with different values in certain situations, depending on what type it is at the time. For more information, see the section on Type Juggling. The type comparison tables may also be useful, as they show examples of various type-related comparisons.
add a note
User Contributed NotesIntroduction
Anonymous
29-Mar-2009 06:21
29-Mar-2009 06:21