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PHP gettype 获取变量的类型

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()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()is_string()


PHP gettype note #1

I did some benchmarking and your method here is alot slower then using the actual gettype(); (Using php 5.3.4)

PHP gettype note #2

This function returns string representation of type. This is generalization of get_class(). I try to order is_* tests by density of occurence, but is bad idea to use result of this call in conditions for performance reasons, usefull and better than gettype for debugging messages.
Note, that last line should not be never executed.
Also has no sense to make input parameter optional.

<?php
function get_type($var)
{
    if(
is_object($var))
        return
get_class($var);
    if(
is_null($var))
        return
'null';
    if(
is_string($var))
        return
'string';
    if(
is_array($var))
        return
'array';
    if(
is_int($var))
        return
'integer';
    if(
is_bool($var))
        return
'boolean';
    if(
is_float($var))
        return
'float';
    if(
is_resource($var))
        return
'resource';
   
//throw new NotImplementedException();
   
return 'unknown';
}
?>

PHP gettype note #3

I wanted to compare the type of 2 vars.
1st method: Use this Funktion (gettype) and compare with ==
2nd method: Compare every type per is_[type]
Here a little Benchmark:
(I had to break line twice..)

<?php
$var1
= "Hallo";
$var2 = "Käsekuchen";
$var3 = 3.141526;
$Start = microtime(true);
for(
$i=0;$i<10000;$i++)
{
if(
is_bool($var1)&&is_bool($var2)||is_int($var1)&&
is_int($var2)||is_string($var1)&&is_string($var2)||
is_object($var1)&&is_object($var2)||is_array($var1)
&&
is_array($var2))
    {
       
//same
   
}
    if(
is_bool($var3)&&is_bool($var2)||is_int($var3)&&
is_int($var2)||is_string($var3)&&is_string($var2)||
is_object($var3)&&is_object($var2)||is_array($var3)
&&
is_array($var2))
    {
       
//same
   
}
}
$time = microtime(true)-$Start;
echo
"Zeit fuer if abfrage:  ".$time."<br>";

$Start = microtime(true);
for(
$i=0;$i<10000;$i++)
{
    if(
gettype($var1)==gettype($var2))
    {
       
//same
   
}
    if(
gettype($var3)==gettype($var2))
    {
       
//same
   
}
}
$time = microtime(true)-$Start;
echo
"Zeit fuer funktion  :  ".$time;
?>

Output:
Zeit fuer if abfrage: 0.0257611274719
Zeit fuer funktion : 0.0139331817627

So the function isnt so slow...

Lukas

PHP gettype note #4

After some testing I found a bug in my function "myGetType":
The check for "is_callable" was done before "is_string", so that something like <?php echo myGetType("max"); ?> would output: "function reference" instead of "string"

"is_callable" and "is_string" can't be checked together in this method, so I've removed the check for is_callable because it's a very rare usage case and if it's a valid string the check for is_callable never executes because is_string would be reached first (or vice-versa).

So here is the new function without "is_callable"-Check:
<?php
   
/**
     * Returns the type of the var passed.
     *
     * @param mixed $var Variable
     * @return string Type of variable
     */
   
function myGetType($var)
    {
        if (
is_array($var)) return "array";
        if (
is_bool($var)) return "boolean";
        if (
is_float($var)) return "float";
        if (
is_int($var)) return "integer";
        if (
is_null($var)) return "NULL";
        if (
is_numeric($var)) return "numeric";
        if (
is_object($var)) return "object";
        if (
is_resource($var)) return "resource";
        if (
is_string($var)) return "string";
        return
"unknown type";
    }
?>

PHP gettype note #5

This is my work around for the gettype warning. Hope some find it useful.

<?php
   
/**
     * Returns the type of the passed var
     * - PHP warns against using gettype(), this is my workaround
     *
     * @param mixed $var
     * @return string
     */
   
function myGetType($var)
    {
        if (
is_array($var)) return "array";
        if (
is_bool($var)) return "boolean";
        if (
is_callable($var)) return "function reference";
        if (
is_float($var)) return "float";
        if (
is_int($var)) return "integer";
        if (
is_null($var)) return "NULL";
        if (
is_numeric($var)) return "numeric";
        if (
is_object($var)) return "object";
        if (
is_resource($var)) return "resource";
        if (
is_string($var)) return "string";
        return
"unknown type";
    }
?>

[EDITOR thiago NOTE: Code has been updated by PPKu-N0-SPAM-schy at mediasoft-berlin dot de]

PHP gettype note #6

In some rare cases a class instance object returns false when an object but gettype() returns "object".

<?php
$x
= new classvar();

$save = serialize($x);

// ......

$obj = unserialize($save);
// here sometimes is_object() returns FALSE
if (is_object($x) || gettype($x) === "object")
{
  
// ... do something
}
?>

PHP gettype note #7

The function returns "unicode" for Unicode strings in PHP6.

PHP gettype note #8

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
?>

PHP gettype note #9

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 est.php on line 2 PHP Warning: Division by zero in C: est.php on line 5

PHP gettype note #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.

<?php
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