This is my array
$sub = array("English"=>"12","Hindi"=>"12","History"=>"12","Geography"=>"12","Mathematics"=>"12","Physics"=>"12","Chemistry"=>"12","Biology"=>"12");
Want to pass this entire array as the parameter of a function & want to sum up the marks(array values) using the function
function sum_marks($sub){--Function body--
}
I don't know if this is the proper syntax for passing an array to a function, help!!
Is this you are looking for?
$mySum = array_sum($sub);
Yes, it is the appropriate syntax for passing an array as an argument to a function.
However, you might consider adding a type declaration for the $sub argument:
function sum_marks(array $sub)
{
return array_sum($sub);
}
Type declarations allow functions to require that parameters are of a certain type at call time. If the given value is of the incorrect type, then an error is generated: in PHP 5, this will be a recoverable fatal error, while PHP 7 will throw a TypeError exception.
However, you really probably just want to use array_sum() directly.
For reference, see:
http://php.net/manual/en/functions.arguments.php#functions.arguments.type-declaration
http://php.net/manual/en/function.array-sum.php
Try this. It will create a function that has a reference to your array. When you change the array you can call the product of the function, and it will recalculate the sum.
$array = ['English' => '12', 'Swedish' => '12'];
function arraySumCb(&$subject) {
return function () use (&$subject) {
return array_sum($subject);
};
}
$sum = arraySumCb($array);
echo $sum(); // 24
$array['Swedish'] = '15';
echo $sum(); // 27
$array['Swedish'] = '10';
echo $sum(); // 22
Edit: This is how I would do it.
$array = ['English' => '12', 'Swedish' => '12'];
class SumMarks {
private $_subject;
public function __construct(array &$subject = []) {
$this->_subject = &$subject;
}
public function __toString() {
return "" . array_sum($this->_subject);
}
}
$sum = new SumMarks($array);
echo $sum; // 24
$array['Swedish'] = '10';
echo $sum; // 22
Edit: Proper use of PHP anonymous functions
I dont understand your question, please ask with specific question. .
But maybe this what are you want :
function sum_marks($sub){
$result = array_sum($sub);
retrun $result;
}
Related
I need to realize function "calc" that works like that:
$sum = function($a, $b) { return $a + $b; };
calc(5)(3)(2)($sum); // 10
calc(1)(2)($sum); // 3
calc(2)(3)('pow'); // 8
I can write something like this:
function calc(){;
print_r(func_get_args());
return __FUNCTION__;
}
calc(3)(5)(2)('sum');
and it print Array ( [0] => 3 ) Array ( [0] => 5 ) Array ( [0] => 2 ) Array ( [0] => sum ).
So, when I get 'sum' in my function, i should have an array with all previous arguments.
But i have no idea, how can i pass current argument in next function call to manipulate all of them on last iteration. Or is there some sort of recursive solution?
What you're talking about is called Currying. The following code will require PHP 7, since it involves invoking a function returned from another one, which wasn't possible until PHP's Abstract Syntax Tree was implemented in that version.
First things first, you'll need a new sum() function that can operate on an arbitrary number of variables:
$sum = function(...$args) { return array_sum($args); };
Secondly, the important part. A function that returns a new anonymous function, accumulating the arguments as it goes. When you finally pass it something callable (either your $sum function, or a built-in function name like pow), it'll execute it, unpacking the arguments that it's built up.
function calc($x)
{
return function($y = null) use ($x)
{
if (is_callable($y)) {
return $y(...$x);
} else {
$args = (array) $x;
$args[] = $y;
return calc($args);
}
};
}
echo calc(5)(3)(2)($sum); // 10
echo calc(1)(2)($sum); // 3
echo calc(2)(3)('pow'); // 8
See https://3v4l.org/r0emm
(Note that internal functions will be limited to operating on the number of arguments they are defined to take - calc(2)(3)(4)('pow') will raise an error.)
This isn't a particularly common pattern to use (which is probably why you've found it hard to track down), so please for everyone who reads it's sake, think carefully about where you use it.
Credit to the curryAdd answer in this question for the starting blocks.
Edit: I stand corrected, you don't require globals it seems! Definitely use the #iainn's answer over this one.
So to achieve this you're going to have to use globals if you're not doing it within a class to maintain current state. You can see a working example of the below code here (note that it only works for PHP version 7 and above)
<?php
$sum = function(...$args) {
return array_sum($args);
};
function calc(...$args) {
global $globalArguments;
if (is_callable($args[0])) {
$callback = $args[0];
$arguments = array_map(function ($arg) {
return $arg[0];
}, $globalArguments);
return $callback(...$arguments);
}
$globalArguments[] = $args;
return __FUNCTION__;
}
echo calc(3)(2)($sum); // 5
I don't know why you want to do this, but I don't suggest it in production, globals aren't something that should really be used if you can avoid it.
function calc(int $value, Callable $function = null)
{
return function ($v) use ($value, $function) {
$f = function ($call) use ($value, $function) {
return (is_callable($call) && is_callable($function)) ? $call($function($call), $value) : $value;
};
return is_callable($v) ? $f($v) : calc($v, $f);
};
}
I have the following codes.
<?php
class Reg {
private $pros = array();
public function __set($key,$val) {
$this->pros($key)= $val;
}
public function __get($key) {
return $this->pros($key);
}
}
$reg= new Reg;
$reg->tst="tst";
echo $reg->tst;
?>
But when executing this script I got the error following.
Fatal error : can't use method return value in write context in line 5
I believe that to add an element to array is possible like the above.
$array = array();
$array('key')='value';
Please make clear that I was wrong.
Thanks
The is because of you are trying to set a functions return value. $this->pros($key) means calling pros($key) function. Not setting a value to $pros array.
The syntax is wrong. Setting values to array be -
$array['index'] = 'value';
Change
$this->pros($key)= $val; -> $this->pros[$key]= $val;
and
return $this->pros[$key];
Working code
$this->pros[$key] = $value;
OR
$keys = array($key);
$this->pros = array_fill_keys($keys,$value);
The array_fill_keys() function fills an array with values, specifying keys.
Syntax:
array_fill_keys(keys,value);
First look at my php script:
<?php
class user{
public function check_array($option['myname']=FALSE){
if($option['myname']==False){
echo $option['yourname'];
}else{
echo $option['myname'];
}
}
$user = new user();
$option['yourname']='Mr. X';
$option['myname']='Mamun';
$user->check_array();
?>
Objective is my script is to pass argument/parameter in class method call. If the parameter is an array and if I want to declare an array element as False (by default), the how to declare it in proper way.
The above code is not working. It is showing following error:
Parse error: syntax error, unexpected '[', expecting ')' ..........
How can I declare the above array element in right way?
function check_array(array $option) {
$option += array('myname' => false, 'yourname' => null);
if ($option['myname'] !== false) {
echo $option['myname'];
} else {
echo $option['yourname'];
}
}
$option = array(
'yourname' => 'Mr. X',
'myname' => 'Mamun'
);
check_array($option);
You cannot declare the array structure and its default content as part of the function signature, it's simply not possible and arguably makes little sense. You can simply amend the array with default values programmatically inside the function with + though. You can also require the argument to be an array through type hinting, which I've done above.
I've also taken the liberty to remove anything related to class, since it's unnecessary for this example.
You can't declare default values to keys of function arguments.
You can achieve your goal in several ways, e.g.:
public function check_array($option) {
if (is_array($option) && !isset($option['myname'])) {
$option['myname'] = false;
}
// do something else
}
I've a function which returns an array. To return the value of that array I do something like this:
$obj->methodname()[keyvalue];
This works in php 5.4 only. I want to make this code work in lower php versions.
My code:
class ObjectTest {
public $ar;
function __construct() {
$this->ar = array(
1 => 'beeldscherm',
2 => 'geluidsbox',
3 => 'toetsenbord',);
}
public function arr(){
return $this->ar;
}
}
$obj = new ObjectTest();
//by calling the method and putting square brackets and the key of the element
var_dump($obj->arr()[2]);
I've rewritten the code for lower versions like this:
public function arr($arg = null){
if(is_null($arg)){
return $this->ar;
}
return $this->ar[$arg];
}
I'm doubting if this solution is an elegant one. What would you say? Any better solutions?
You can do like, store array in a variable and than access particular array index.
$arrList = var_dump($obj->arr());
echo $arrList[2];
how can I get a object from an array when this array is returned by a function?
class Item {
private $contents = array('id' => 1);
public function getContents() {
return $contents;
}
}
$i = new Item();
$id = $i->getContents()['id']; // This is not valid?
//I know this is possible, but I was looking for a 1 line method..
$contents = $i->getContents();
$id = $contents['id'];
You should use the 2-line version. Unless you have a compelling reason to squash your code down, there's no reason not to have this intermediate value.
However, you could try something like
$id = array_pop($i->getContents())
Keep it at two lines - if you have to access the array again, you'll have it there. Otherwise you'll be calling your function again, which will end up being uglier anyway.
I know this is an old question, but my one line soulution for this would be:
PHP >= 5.4
Your soulution should work with PHP >= 5.4
$id = $i->getContents()['id'];
PHP < 5.4:
class Item
{
private $arrContents = array('id' => 1);
public function getContents()
{
return $this->arrContents;
}
public function getContent($strKey)
{
if (false === array_key_exists($strKey, $this->arrContents)) {
return null; // maybe throw an exception?
}
return $this->arrContents[$strKey];
}
}
$objItem = new Item();
$intId = $objItem->getContent('id');
Just write a method to get the value by key.
Best regards.