|
func_num_args
Returns the number of arguments passed to the function
(PHP 4, PHP 5)
Gets the number of arguments passed to the function. This function may be used in conjunction with func_get_arg() and func_get_args() to allow user-defined functions to accept variable-length argument lists. ExamplesExample 760. func_num_args() example<?php Notes
Note:
Because this function depends on the current scope to determine parameter details, it cannot be used as a function parameter. If you must pass this value, assign the results to a variable, and pass the variable.
See Also
Code Examples / Notes » func_num_argsfriz
This function comes in extremely handy in OO Classes. My focus is currently PHP 4, but this technique probably works just as well in PHP 5. Class foo { // constructor, other methods, etc function somedata($somedata = '') { if (func_num_args() > 0) { $this->somedata = $somedata; } return $this->somedata; } } This allows for a default value to be set, while not requiring the parameter. (Yes, I'm aware that it only warns when you do, but I think this is a little cleaner) thalis
The idea of func_get_args() is to construct functions of variable number of parameters like function var_param_func(){ if(func_num_args()==0){ //do one thing } if(func_num_args()==1) //do another thing //get the args with func_get_args() } } neelam_ab2003
Just adding a note to JARED's Note. func_num_args() works if and only if called from within a function definition BECAUSE it calculates the number of arguments sent while function calling. That is why it gives '1' in helloWorld("HelloWorld!") and '2' in helloWorld("HelloWorld!", "HowdyWorld!") - There is nothing to do with DEFAULT args. If you call the same function as helloWorld(); "No args passed" It will give a warning for wrong function call ("Warning: Missing argument 1 for helloWorld()") and the result of func_num_args() will be '0'. jared
Just a note for anyone wondering. This function doesn't include params that have a default value, unless you pass one in to overwrite the default param value. Not sure if that makes sense, so here's an example: function helloWorld($ArgA, $ArgB="HelloWorld!") { return func_num_args(); } // The following will return 1 $Returns1 = helloWorld("HelloWorld!"); // The following will return 2 $Returns2 = helloWorld("HelloWorld!", "HowdyWorld!"); ashley
If you want to pass the parameters on intact to another function, use func_get_args and call_user_func_array (careful - this one is only available in recent PHP versions). For example: /* Print an HTML tag. This accepts a variable number of arguments: the first should be the name of the tag, followed by pairs of arguments that describe keys and values. The values are printed with surrounding double quote characters. */ function printTag() { $numArgs = func_num_args(); if ($numArgs < 1) die("printTag given no arguments"); echo "<" . func_get_arg(0); for ($i = 1; $i < $numArgs; $i+=2) { echo " " . func_get_arg($i); if ($i+1 < $numArgs) echo "=\"" . func_get_arg($i+1) . "\""; } echo ">"; } /* Print an HTML tag with a newline on the end */ function printTagNL() { $args = func_get_args(); call_user_func_array("printTag", $args); echo "\n"; } printTagNL("input", "type", "hidden", "name", "SORTORDER", "value", $columnNo); padron
func_num_args(), func_get_args() and func_get_arg() can be very useful to emulate overloading in PHP. Suppose you have a class to add a user in a system, and that you want to allow 2 ways of doing it. The first way would be passing an array with all the user info in it, and the second way would be passing each user attribute as a single argument. <?php class Test { function insertUser() { // gets the number of parameters $numArgs = func_num_args(); // make decisions based on the arguments number if ($numArgs == 1) { // if it's only one argument, we suppose that it is an array with user info // gets the first argument $user = func_get_arg(0); // checks if it really is an array if (is_array($user)) { // here you should check if the array contains all necessary fields // adds the user echo "User added.<br/>"; echo "ID: " . $user["id"] . "<br/>"; echo "NAME: " . $user["name"] . "<br/>"; echo "EMAIL: " . $user["email"] . "<br/>"; } else { // generates an error if argument is not an array echo "Argument is not an array: " . $user . ".<br/>"; } } else if ($numArgs == 3) { // if the function receives 3 arguments, we assume that they // are 'id', 'name' and 'email' respectively // inserts the user into the system echo "User added.<br/>"; echo "ID: " . func_get_arg(0) . "<br/>"; echo "NAME: " . func_get_arg(1) . "<br/>"; echo "EMAIL: " . func_get_arg(2) . "<br/>"; } else { // if the number of arguments is different from 1 and 3 // an error will be generated echo "Wrong argument number.<br/>"; echo "Arguments received: " . func_num_args(); } } } // creates an Test object $objTest = new Teste(); // inserts an user passing an array with all his info $objTest->insertUser(array("id" => 1, "name" => "George W. Bush", "email" => "jackass@whitehouse.gov")); echo "<br/>"; // inserts an user providing each attribute as a single argument $objTest->insertUser(2, "Vicente Fox", "iloveusa@disney.com"); echo "<br/>"; // this will generate an error, because only 2 arguments were passed $objTest->insertUser(3, "Tony Blair"); ?> andy
func_num_args() can be used in conjunction with named arguments, also. For example: function DebugShow( $label, $value ) { echo "# " . $label ; if ( func_num_args() > 1 ) echo " = " . $value ; echo " "; } |