get_resource_type
Class instances evaluate to FALSE if they don't have members.
gettype
(PHP 4, PHP 5)
gettype — 获取变量的类型
描述
string gettype
( mixed $var
)
返回 PHP 变量的类型 var .
Warning
不要使用 gettype() 来测试某种类型，因为其返回的字符串在未来的版本中可能需要改变。此外，由于包含了字符串的比较，它的运行也是较慢的。
使用 is_* 函数代替。
返回的字符串的可能值为：
- “boolean”（从 PHP 4 起）
- “integer”
- “double”（由于历史原因，如果是 float 则返回“double”，而不是“float”）
- “string”
- “array”
- “object”
- “resource”（从 PHP 4 起）
- “NULL”（从 PHP 4 起）
- “user function”（只用于 PHP 3，现已停用）
- “unknown type”
对于 PHP 4，你应该使用 function_exists() 和 method_exists() 取代先前将 gettype() 作用于函数的用法。
参见 settype()、is_array()、is_bool()、is_float()、is_integer()、is_null()、is_numeric()、is_object()、is_resource()、is_scalar() 和 is_string()。
add a note
User Contributed Notesgettype
skatebiker at hotmail dot com
22-Feb-2008 09:51
22-Feb-2008 09:51
In some rare cases a class instance object returns false when an object but gettype() returns "object".
$x = new classvar();
$save = serialize($x);
......
$obj = unserialize($save);
// here sometimes is_object() returns FALSE
if (is_object($x) || gettype($x) === "object")
{
... do something
}
sneskid at hotmail dot com
06-Mar-2007 05:56
06-Mar-2007 05:56
I wrote my own gettype function by just using the default is_? functions, but it took twice as long as gettype... So I decided to use gettype with a twist.
Taking the warnings about gettype to heart, and depending on your custom needs, it's worthwhile to dynamically test the gettype result with a known variable, and link the result to a predefined result. Like so:
<?php
/*
dynamically create an array by using known variable types
link with a predefined value
*/
$R=array();
$R[gettype(.0)]='number';
$R[gettype(0)]='number';
$R[gettype(true)]='boolean';
$R[gettype('')]='string';
$R[gettype(null)]='null';
$R[gettype(array())]='array';
$R[gettype(new stdClass())]='object';
// what is
function wis_($v){
global $R;
return $R[gettype($v)];
}
echo wis_('hello') . '<br/>'; // "string"
echo wis_(24) . '<br/>'; // "number"
echo wis_(0.24) . '<br/>'; // "number"
echo wis_(null) . '<br/>'; // "null"
echo wis_($R) . '<br/>'; // "array"
?>
You won't need to worry about changes in gettype's return strings in future versions.
If the result evaluates to false then you know the variable tested is some "other" type.
I also find these useful
<?php
function is_num($v){return (is_int($v) || is_double($v));}
function is_box($v){return (is_array($v)||is_object($v));}
echo is_num(null) . '<br/>'; // false
echo is_num(false) . '<br/>'; // false
echo is_num('123') . '<br/>'; // false
echo is_num(123) . '<br/>'; // true
echo is_num(123.0) . '<br/>'; // true
?>
gilthansNOSPAM at gmail dot com
12-Sep-2005 04:18
12-Sep-2005 04:18
NaN and #IND will return double or float on gettype, while some inexistent values, like division by zero, will return as a boolean FALSE. 0 by the 0th potency returns 1, even though it is mathematically indetermined.
<?php
$number = 5/0;
$number2 = sqrt(-3);
$number3 = pow(0, 0);
$number4 = 0/0;
echo $number."<br />";
echo $number2."<br />";
echo $number3."<br />";
echo $number4."<br />";
echo "<br />";
echo gettype($number)."<br />";
echo gettype($number2)."<br />";
echo gettype($number3)."<br />";
echo gettype($number4);
?>
This will return:
-1.#IND
1
boolean
double
integer
boolean
0
1
1
0
PHP Warning: Division by zero in C\test.php on line 2 PHP Warning: Division by zero in C:\test.php on line 5
matt at appstate
17-Dec-2004 03:10
17-Dec-2004 03:10
Here is something that had me stumped with regards to gettype and is_object.
Gettype will report an incomplete object as such, whereas is_object will return FALSE.
if (!is_object($incomplete_obj)) {
echo 'This variable is not an object, it is a/an ' . gettype($incomplete_obj);
}
Will print:
This variable is not an object, it is a/an object
jose at vocis dot com
15-Sep-2000 12:22
15-Sep-2000 12:22
Also returns "NULL" for variables assigned the return of a function that returned no value via "return;".
<code>
function weird(){
return;
}
$a=weird();
</code>
isset($a) <> 1
empty($a) <> 1
gettype($a) == NULL
-Jose Batista
ojones at dotclick dot com
01-Sep-2000 01:19
01-Sep-2000 01:19
After calling OCIResult to retrieve a NULL result from an Oracle result-set, gettype returns the string 'NULL'.