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1) Get function arguments count

2) Get the first function argument

Variable Scope

PHP has three variable scopes: the global scope, function scope, and class scope.

Variable-length Argument Lists

You can create a function that accepts a variable number of arguments, depending on the circumstance. A typical example of this behaviour is exhibited by the printf() family of functions. <?php echo sprintf("%s %s is %d old", "John", "Smith", 10); // Output: John Smith is 10 old PHP provides three built-in functions to handle variable-length argument lists: func_num_args(), func_get_arg(), func_get_args() <?php function myArray() { $arr = array(); $i = 0; if (func_num_args() == 0) { $arr[] = "Hello World"; } if (func_num_args() > 0) { while($i < func_num_args()) $arr[] = "Hello " . func_get_arg($i++); } return $arr; } print_r(myArray()); // [Hello World] print_r(myArray("John", "Mary")); // [Hello John, Hello Mary] It is rather important to keep in mind that variable-length argument lists are full of potential pitfalls. While they are very powerful, they do tend to make your code confusing.