Quick Fix (3)-PHP: function basis, function parameters, function return value, variable function, anonymous function, closure function, callback function

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Quick Fix (3)-PHP: function basis, function parameters, function return value, variable function, anonymous function, closure function, callback function

Webabcd


Introduced
Quick and fast PHP

• Function basics
• function parameters
• function return value
• Variable functions
• anonymous functions
• Closure function
• callback function

Example
1, the function of the relevant Knowledge point 1 (Basic)
function/function1.php

<?PHP/** * Function Related Knowledge point 1 (Basic)*///The function can be called before the associated function declaration statementF1 ();functionF1 () {Echo"F1"; Echo"<br/>";}//here call F2 () on the wrong//F2 ();$b=true;if($b){    functionF2 ()//This function is declared when the condition is established    {        Echo"F2"; Echo"<br/>"; }}f2 ();//It is wrong to call F4 () here (because F4 's declaration is inside the F3, so call F3 before calling F4)//F4 ();f3 (); F4 ();functionF3 () {Echo"F3"; Echo"<br/>"; functionf4 () {Echo"F4"; Echo"<br/>"; }}

2, the function of the relevant Knowledge point 2 (function parameters)
function/function2.php

<?PHP/** * Function Related Knowledge point 2 (function parameter)*///functions with ParametersF1 ("WEBABCD");functionF1 ($name){    Echo"Hello".$name;//Output:hello WEBABCD    Echo"<br/>";}//function with parameters (argument is reference type)$name= "WEBABCD"; F2 ($name);functionF2 (&$n)//parameter is a reference type{    Echo"Hello".$n;//Output:hello WEBABCD    Echo"<br/>"; $n= "Wanglei";//$n is a reference type, which is the same as a global variable $name point}Echo"Hello".$name;//Output:hello WangleiEcho"<br/>";//functions with parameters (parameters can specify default values)F3 ("Hello");//Output:hello WEBABCDF3 ("Hello", "Wanglei");//Output:hello WangleifunctionF3 ($p 1,$p 2= "WEBABCD")//the default value of a parameter can only be a constant, not an expression{    Echo $p 1.$p 2; Echo"<br/>";}

3, the function of the relevant Knowledge point 3 (function return value)
function/function3.php

<?PHP/** * Function Related Knowledge point 3 (function return value)*///function with return value$result 1= F1 ("WEBABCD");Echo $result 1;Echo"<br/>";functionF1 ($name){    return"Hello".$name;//Output:hello WEBABCD}//return from function with a reference (both the Declaration and the invocation of the function are added &)$result 2= &F2 ();Echo $result 2;//output:1Echo"<br/>";$result 2= 100;//$result 2 is a reference that points to what the $i points to, so the value $i after this sentence is$result 3= &F2 ();Echo $result 3;//output:101Echo"<br/>";function&AMP;F2 ()//This function returns a reference (both the Declaration and the invocation of the function are added &){    Static $i= 0; $i++; return $i;}

4, the function of the relevant knowledge point 4 (variable function, anonymous function, closure function)
function/function4.php

<?PHP/** * Function Related knowledge point 4 (variable function, anonymous function, closure function)*///variable function (variable), the value of the variable as the function namefunctionF1 () {Echo"F1";//output:f1    Echo"<br/>";}functionF2 () {Echo"F2";//Output:f2    Echo"<br/>";}$func= ' F1 ';$func();$func= ' F2 ';$func();//Anonymous FunctionsEcho Preg_replace_callback //Output:username(    ' ~-([A-z]) ~ ',function($match)//Anonymous Functions    {        return Strtoupper($match[1]); }, ' User-name ');//closure Function//$f 3 ("WEBABCD");//This is wrong, for a closure function, the call is made after the declaration statement$f 3=function($name){    Echo"Hello".$name;//Output:hello WEBABCD    Echo"<br/>";}; //don't forget the ";" of the closure function .$f 3("WEBABCD");

5, the function of the relevant Knowledge point 5 (callback function)
function/function5.php

<?PHP/** * Function Related Knowledge point 5 (callback function)*///used to demonstrate how to callback (callback) functionsfunctionmycallbackfunction () {return' Mycallbackfunction ';}classmyclass1{//used to demonstrate how to callback (callback) instance methods     Public functionmyMethod1 () {Echo' MyClass1 myMethod1 '; Echo' <br/> '; }    //used to demonstrate how to callback (callback) class methods     Public Static functionmyMethod2 () {Echo' MyClass1 myMethod2 '; Echo' <br/> '; }}//calling the specified function via Call_user_funcEcho Call_user_func(' Mycallbackfunction ');Echo' <br/> ';$obj 1=NewMyClass1 ();//to invoke the specified method of the specified object via Call_user_funcCall_user_func(Array($obj 1, ' MyMethod1 '));//to invoke the class method of a class by means of Call_user_funcCall_user_func(Array(' MyClass1 ', ' myMethod2 '));//to invoke the class method of a class by Call_user_func (PHP 5.2.3 or above)Call_user_func(' myclass1::mymethod2 ');

Ok
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Quick Fix (3)-PHP: function basis, function parameters, function return value, variable function, anonymous function, closure function, callback function