PHP functions and functions that are unknown

The real power of PHP comes from its functions, but some PHP functions are not fully utilized, and not everyone will read the manual and function reference page by page from start to end, here we will introduce you to these practical functions and functions. 51CTO recommended topic: PHP development basics the real power of PHP comes from its functions, but some PHP functions are not fully utilized, not everyone will read the manual and function reference page by page from start to end. here we will introduce you to these useful functions and functions.

1. functions with any number of parameters

You may already know that PHP allows defining functions with optional parameters. However, there are methods that fully allow any number of function parameters. The following is an example of an optional parameter:

 
 

  
  
Reference content is as follows:
  
  
 
  
  
// Functionwith2optionalarguments
  
  
Functionfoo ($ arg1 = ", $ arg2 = "){
  
  
 
  
  
Echo "arg1: $ arg1 \ n ";
  
  
Echo "arg2: $ arg2 \ n ";
  
  
 
  
  
}
  
  
 
  
  
Foo ('hello', 'World ');
  
  
/* Prints:
  
  
Arg1: hello
  
  
Arg2: world
  
  
*/
  
  
 
  
  
Foo ();
  
  
/* Prints:
  
  
Arg1:
  
  
Arg2:
  
  
*/
 
 

Now let's see how to create a function that can accept any number of parameters. This time, you need to use the func_get_args () function:

1. Reference content is as follows:
3. // Yes, theargumentlistcanbeempty
4. Functionfoo (){
6. // Returnsanarrayofallpassedarguments
7. $ Args = func_get_args ();
9. Foreach ($ argsas $ k =>$ V ){
10. Echo "arg". ($ k + 1). ": $ v \ n ";
11. }
13. }
15. Foo ();
16. /* Printsnothing */
18. Foo ('Hello ');
19. /* Prints
20. Arg1: hello
21. */
23. Foo ('hello', 'World', 'Again ');
24. /* Prints
25. Arg1: hello
26. Arg2: world
27. Arg3: again
28. */