Function as Array Value

Function as array value

You can "reference" any function. A function reference is not a reference in the sense of "address in memory" or something. It's merely the name of the function.

<?php

$functions = array(
  'regular' => 'strlen',
  'class_function' => array('ClassName', 'functionName'),
  'object_method' => array($object, 'methodName'),
  'closure' => function($foo) {
    return $foo;
  },
);

// while this works
$functions['regular']();
// this doesn't
$functions['class_function']();

// to make this work across the board, you'll need either
call_user_func($functions['object_method'], $arg1, $arg2, $arg3);
// or
call_user_func_array($functions['object_method'], array($arg1, $arg2, $arg3));

Javascript Array of Functions

var array_of_functions = [
    first_function,
    second_function,
    third_function,
    forth_function
]

and then when you want to execute a given function in the array:

array_of_functions[0]('a string');

Write a function that takes an array by calling another function to return a value and store it on a new array

You can simply push callback return into array and return that same array from your custom fucntion.

You can also modify original array using index.

const customMap = (arr, callback) => {
  const finalArr = []
  arr.forEach((item, index) => {
    const res = callback(item)
    finalArr.push(res)
    arr[index] = res // This will modify original array
  })

  return finalArr
}

const numbers = [1, 2, 3, 4, 5];

const newNumbers = customMap(numbers, (number) => {
  return number + 3;
});

console.log(newNumbers);
console.log(numbers);

Calling functions as dynamic function as array values in javascript

Use function names rather than using strings

function getId(arr) {  for (let i in arr) {    console.log("Function getId " + arr[i]);  }}
function getMarker(arr) {  for (let i in arr) {    console.log("Function getMarker " + arr[i]);  }}const PAGEAPP = {  processes: [getId, getMarker],  init: () => {    for (let foo of PAGEAPP.processes) {      foo([1, 2, 3]);
    }  },}
PAGEAPP.init()

Return array in a function

In this case, your array variable arr can actually also be treated as a pointer to the beginning of your array's block in memory, by an implicit conversion. This syntax that you're using:

int fillarr(int arr[])

Is kind of just syntactic sugar. You could really replace it with this and it would still work:

int fillarr(int* arr)

So in the same sense, what you want to return from your function is actually a pointer to the first element in the array:

int* fillarr(int arr[])

And you'll still be able to use it just like you would a normal array:

int main()
{
  int y[10];
  int *a = fillarr(y);
  cout << a[0] << endl;
}

Can you store a function in a PHP array?

The recommended way to do this is with an anonymous function:

$functions = [
  'function1' => function ($echo) {
        echo $echo;
   }
];

If you want to store a function that has already been declared then you can simply refer to it by name as a string:

function do_echo($echo) {
    echo $echo;
}

$functions = [
  'function1' => 'do_echo'
];

In ancient versions of PHP (<5.3) anonymous functions are not supported and you may need to resort to using create_function (deprecated since PHP 7.2):

$functions = array(
  'function1' => create_function('$echo', 'echo $echo;')
);

All of these methods are listed in the documentation under the callable pseudo-type.

Whichever you choose, the function can either be called directly (PHP ≥5.4) or with call_user_func/call_user_func_array:

$functions['function1']('Hello world!');

call_user_func($functions['function1'], 'Hello world!');

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