PHP uses func_get_args and func_num_args functions to implement function overloading examples, funcnumargs_PHP tutorial

PHP uses func_get_args and func_num_args functions to implement function overloading examples, funcnumargs

The example in this article describes how PHP uses the func_get_args and func_num_args functions to implement function overloading. Share it with everyone for your reference. The specific method analysis is as follows:

Friends who study PHP all know that PHP itself does not have function overloading, let alone how to use it like Java and C. But if we take a deeper look, we will find that we can use func_get_args() and func_num_args in PHP. The () function implements function overloading. Here are two examples of function overloading. These two functions implement function overloading.

1. Default parameters. If this is not a required parameter in a function, and the corresponding default value is added, the corresponding function can be completed. The code is as follows:

Copy code The code is as follows:

function overloadFun($param1, $param2 = '1',$param3 = true)
{
// do something
}

Using functions func_get_args() and call_user_func_array(), the PHP code is as follows:

Copy code The code is as follows:

function rewrite() { 
$args = func_get_args();
if(func_num_args() == 1) { 
func1($args[0]);
} else if(func_num_args() == 2) { 
func2($args[0], $args[1]);
} 
} 
 
function func1($arg) {
echo $arg;
} 
 
function func2($arg1, $arg2) {
echo $arg1, ' ', $arg2;
} 
 
rewrite('PHP'); //Call func1
rewrite('PHP','China'); //Call func2

2. Use the default value to get the results you want based on the input. The code is as follows:

Copy code The code is as follows:

function test($name="Xiao Li",$age="23"){ 
echo $name." ".$age;
} 
test();
echo "
";
test("a");
echo "
";
test("a","b");

3. Use the __call($name, $arg) function for processing. The code is as follows:

Copy code The code is as follows:

class OverLoad{
function __call($name, $args)
{
if($name=='overloadFun')
{
switch(count($args))
{
case 0: $this->overloadFun0();break;
Case 1: $this->overloadFun1($args[0]); break;
case 2: $this->overloadFun2($args[0], $args[1]); break;
default: //do something
Break;
}  
}
}
     
function overloadFun0()
{
echo 0;
}

function overloadFun1($var1)
{
echo $var1;
}

function overloadFun2($var1,$var2)
{
 
echo $var1 $var2;
}  
} 
$test=new OverLoad();
$test->overloadFun()."
".
$test->overloadFun(1)."
".
$test->overloadFun(1,2)."
";
?>

With such methods, we can use them to implement simple function overloading, but one thing to note is that PHP, as a weakly typed language, cannot directly implement overloading like strongly typed languages ​​such as Java and C. Download, at least not now, we don’t know if it will be available in future versions.

I hope this article will be helpful to everyone’s PHP programming design.

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