Detailed explanation of PHP custom functions call_user_func and call_user_func_array_PHP tutorial

The call_user_func function is similar to a special method of calling a function. The method of use is as follows:

Copy code The code is as follows:

function a($b,$c)
{
echo $b;
echo $c;
}
call_user_func('a', "111","222");
call_user_func('a', "333","444");
//Display 111 222 333 444
?>

It is strange to call the method inside the class, actually Array is used. I don’t know what the developers thought about it. Of course, new is omitted, which is also full of novelty:

Copy code The code is as follows:

class a {
function b($c)
{
echo $c;
}
}
call_user_func(array("a", "b"),"111");
//Display 111
?>

The call_user_func_array function is very similar to call_user_func, except that the parameters are passed in a different way , making the structure of the parameters clearer:

Copy code The code is as follows:

function a($b, $c)
{
echo $b;
echo $c;
}
call_user_func_array('a', array("111", "222"));
//Display 111 222
?>

The call_user_func_array function can also call methods inside the class

Copy code The code is as follows:

Class ClassA
{
function bc($b, $c) {
$bc = $b + $c;
echo $bc;
}
}
call_user_func_array(array('ClassA','bc'), array("111", "222"));
//Display 333
?>

Both the call_user_func function and the call_user_func_array function support references, which makes them more functionally consistent with ordinary function calls:

Copy code The code is as follows:

function a(&$b)
{
$b++;
}
$c = 0;
call_user_func('a', &$c) ;
echo $c;//Display 1
call_user_func_array('a', array(&$c));
echo $c;//Display 2

php The simple usage of call_user_func_array
Today in the group, a person named Lewis asked about the usage of call_user_func_array. Since I have never used it before, I couldn’t say anything, so I looked at the manual and found that it is written like this:
call_user_func_array
(PHP 4 >= 4.0.4, PHP 5)
call_user_func_array -- Call a user function given with an array of parametersDescription
mixed call_user_func_array ( callback function, array param_arr )
Call a user defined function given by function, with the parameters in param_arr.
Then there is another example:

Copy code The code is as follows:

function foobar($arg, $arg2) {
echo __FUNCTION__, " got $arg and $arg2n";
}
class foo {
function bar($arg, $arg2) {
echo __METHOD__, " got $arg and $arg2n";
}
}
// Call the foobar() function with 2 arguments
call_user_func_array ("foobar", array("one", "two"));
// Call the $foo->bar() method with 2 arguments
$foo = new foo;
call_user_func_array( array($foo, "bar"), array("three", "four"));
?>

The output of the above routine is similar to:
foobar got one and two
foo::bar got three and four
Example #2 call_user_func_array() using namespace name

Copy code The code is as follows:

namespace Foobar;
class Foo {
static public function test($name) {
print "Hello {$name}!n";
}
}
// As of PHP 5.3.0
call_user_func_array(__NAMESPACE__ .'Foo::test', array('Hannes'));
// As of PHP 5.3 .0
call_user_func_array(array(__NAMESPACE__ .'Foo', 'test'), array('Philip'));
?>

The output of the above routine is similar to :
Hello Hannes!
Hello Philip!
Example #3 Using lambda function

Copy code The code is as follows:

$func = function($arg1, $arg2) {
return $arg1 * $arg2;
};
var_dump(call_user_func_array($func, array( 2, 4))); /* As of PHP 5.3.0 */
?>

The above routine will output:
int(8)
I believe you should understand a little after reading the example, right?
This is how I understand this function. If it is wrong, I hope you experts will not laugh at it:
The real usage of this function is somewhat similar to function overloading, because its first parameter is character type , which is the name of the function. The second parameter is an array. We can regard it as each parameter of the function. In fact, this is how it is used. If you have read my previous article: Pseudo-overloading of PHP, maybe You can understand that it is precisely because of the existence of this function that I found that function overloading can also be used like this:

Copy code The code is as follows:

/**
* After I finished writing the example, I thought it was done, but I met someone asking about call_user_func_array() and read the manual
* It turns out that the test function I above can be simplified into the following example,
*/
function otest1 ($a)
{
echo( 'a parameter' );
}
function otest2 ( $a, $ b)
{
echo( 'Two parameters' );
}
function otest3 ( $a ,$b,$c)
{
echo( 'Three ' );
}
function otest ()
{
$args = func_get_args();
$num = func_num_args();
call_user_func_array( 'otest'.$num, $args );
}
otest(1,2);

See? My initial writing method is mentioned in the article Pseudo-overloading in PHP, for reference only. . . .

http://www.bkjia.com/PHPjc/323837.htmlwww.bkjia.comtruehttp: //www.bkjia.com/PHPjc/323837.htmlTechArticleThe call_user_func function is similar to a special method of calling a function. The method of use is as follows: Copy the code The code is as follows: function a ($b,$c) { echo $b; echo $c; } call_user_func('a', "111...