Php длина массива length

Php длина массива length

// Before php 5.4
$array = array(1,2,3);

// since php 5.4 , short syntax
$array = [1,2,3];

// I recommend using the short syntax if you have php version >= 5.4

Used to creating arrays like this in Perl?

Looks like we need the range() function in PHP:

$array = array_merge (array( ‘All’ ), range ( ‘A’ , ‘Z’ ));
?>

You don’t need to array_merge if it’s just one range:

There is another kind of array (php>= 5.3.0) produced by

$array = new SplFixedArray(5);

Standard arrays, as documented here, are marvellously flexible and, due to the underlying hashtable, extremely fast for certain kinds of lookup operation.

Supposing a large string-keyed array

$arr=[‘string1’=>$data1, ‘string2’=>$data2 etc. ]

when getting the keyed data with

php does *not* have to search through the array comparing each key string to the given key (‘string1’) one by one, which could take a long time with a large array. Instead the hashtable means that php takes the given key string and computes from it the memory location of the keyed data, and then instantly retrieves the data. Marvellous! And so quick. And no need to know anything about hashtables as it’s all hidden away.

However, there is a lot of overhead in that. It uses lots of memory, as hashtables tend to (also nearly doubling on a 64bit server), and should be significantly slower for integer keyed arrays than old-fashioned (non-hashtable) integer-keyed arrays. For that see more on SplFixedArray :

Unlike a standard php (hashtabled) array, if you lookup by integer then the integer itself denotes the memory location of the data, no hashtable computation on the integer key needed. This is much quicker. It’s also quicker to build the array compared to the complex operations needed for hashtables. And it uses a lot less memory as there is no hashtable data structure. This is really an optimisation decision, but in some cases of large integer keyed arrays it may significantly reduce server memory and increase performance (including the avoiding of expensive memory deallocation of hashtable arrays at the exiting of the script).

When creating arrays , if we have an element with the same value as another element from the same array, we would expect PHP instead of creating new zval container to increase the refcount and point the duplicate symbol to the same zval. This is true except for value type integer.
Example:

$arr = [‘bebe’ => ‘Bob’, ‘age’ => 23, ‘too’ => 23 ];
xdebug_debug_zval( ‘arr’ );

(refcount=2, is_ref=0)
array (size=3)
‘bebe’ => (refcount=1, is_ref=0)string ‘Bob’ (length=3)
‘age’ => (refcount=0, is_ref=0)int 23
‘too’ => (refcount=0, is_ref=0)int 23

but :
$arr = [‘bebe’ => ‘Bob’, ‘age’ => 23, ‘too’ => ’23’ ];
xdebug_debug_zval( ‘arr’ );

(refcount=2, is_ref=0)
array (size=3)
‘bebe’ => (refcount=1, is_ref=0)string ‘Bob’ (length=3)
‘age’ => (refcount=0, is_ref=0)int 23
‘too’ => (refcount=1, is_ref=0)string ’23’ (length=2)
or :

$arr = [‘bebe’ => ‘Bob’, ‘age’ => [1,2], ‘too’ => [1,2] ];
xdebug_debug_zval( ‘arr’ );

(refcount=2, is_ref=0)
array (size=3)
‘bebe’ => (refcount=1, is_ref=0)string ‘Bob’ (length=3)
‘age’ => (refcount=2, is_ref=0)
array (size=2)
0 => (refcount=0, is_ref=0)int 1
1 => (refcount=0, is_ref=0)int 2
‘too’ => (refcount=2, is_ref=0)
array (size=2)
0 => (refcount=0, is_ref=0)int 1
1 => (refcount=0, is_ref=0)int 2

This function makes (assoc.) array creation much easier:

function arr (. $array )< return $array ; >
?>

It allows for short syntax like:

$arr = arr ( x : 1 , y : 2 , z : 3 );
?>

Instead of:

$arr = [ «x» => 1 , «y» => 2 , «z» => 3 ];
// or
$arr2 = array( «x» => 1 , «y» => 2 , «z» => 3 );
?>

Sadly PHP 8.2 doesn’t support this named arguments in the «array» function/language construct.

Источник

PHP Array Length: How to Find Array Length in PHP [With Examples]

Below is the example we can consider as key and value pair:

Note: we categorize Arrays as “indexed array” and “associative array” based on the key stipulation. The Indexed array has a default index that starts with ‘0’.The associative array includes the user-defined key index. We can use the keys for strings and natural numbers.

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How to create an Array in PHP?

$animals = array(“Bear”, “Leopard”, “Tiger”);

$animals = array(“Leopard”=>”Wild”, “Cow”=>”Domestic”, “Lion”=>”Wild”);

// loop through associative array and get key-value pairs

foreach($animals as $key => $value)

echo “Key=” . $key . “, Value=” . $value;

//two-dimensional array definition declaration

// two-dimensional array iteration declaration

Below is the image as a perfect example for the three-dimensional array:

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PHP | sizeof() Function

The sizeof() function is a built-in function in PHP, and we can use it to count the number of elements present in an array countable object.

Parameter: As per the above syntax example, this function accepts two parameters.

• array: This parameter defines the array which contains elements which we need to count.
• mode: This is an optional parameter, and here we specify the mode of the function. It can take two types of values as per the below:
  • 0: It is default, does not count all elements of multidimensional arrays
  • 1: It Counts the array recursively (It counts all the elements with multidimensional arrays)

  How to Check if a Value Exists in an Array in PHP

  Check if the value exists in an array in PHP

  Step 1 – Use the PHP in_array() function to test if a value exists in an array or not.

  Step 2 – Define the in_array() function

  As per the below code snippet Example:

  $zoo = array(“Leopard”, “Tiger”, “Elephant”, “Zebra”, “Rhino”, “Dear”);

  echo “The elephant was found in the zoo.”;

  echo “The tiger was found in the zoo.”;

  In-Demand Software Development Skills

  How to Count all Elements or Values in an Array in PHP

  We can use the PHP count() or sizeof() function to get the particular number of elements or values in an array.

  • The count() and sizeof() function returns 0 for a variable that we can initialize with an empty array.
  • If we do not set the value for a variable, it returns 0.

  Below is the code snippet:

  $days = array(“Sun”, “Mon”, “Tue”, “Wed”, “Thu”, “Fri”, “Sat”);

  How to Print or Echo all the Values of an Array in PHP

  • For printing the array values here we have different ways
  • The easiest method we have foreach loop

  As per the below example, we are repeating the $colors array and print all its elements using the echo or print statement.

  Below is the code snippet:

  $colors = array(“Yellow”, “Purple”, “Red”, “Brown”, “Skyblue”);

  // Loop through colors array

  How to Display Array Structure and Values in PHP

  Use the PHP print_r() or var_dump() Statement

  • For checking the structure and values of an array.
  • You can either use the PHP print_r() or var_dump() statement to see or check the structure and values of an array with an easily readable format on the screen.
  • The var_dump() statement provides better information than print_r().

  Below is the code snippet example we can consider for this:

  $cities = array(“Canada”, “Australia”, “New Jersey”);

  How to Remove the Last Element From an Array in PHP

  Use the PHP array_pop() function

  • For removing the particular value or element from the end of an array.
  • The array_pop() function returns the last value of an array.
  • If the array is empty (without element value in an array list), the returned value will be NULL.

  Below is the code snippet Example to explain how this function runs:

  $sports = array(“Tennis”, “Cricket”, “BasketBall”, “Badminton”);

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  Conclusion

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  Software Engineering Manager @ upGrad. Passionate about building large scale web apps with delightful experiences. In pursuit of transforming engineers into leaders.

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  Frequently Asked Questions (FAQs)

  Arrays are useful data structures in PHP, which can be used to store multiple values under a single named variable, that too without any need of specifying the type of each individual value. Arrays are one of the fundamental data types in PHP. An array is a collection of elements which can be referenced by an index. You can add new elements, remove existing elements, or change the value stored in any element of an array.

  Finding the length of an array can be quite useful especially in cases where you want to loop through the array and fetch all or some elements inside it. If you want to find the length of an array in PHP, you can use the sizeof function and use the echo command along with it to print the length. The second method is using a function called: count(). This function differs in that it returns the number of elements in an array or object (not just their key values) and also counts the number of array levels in multidimensional arrays.

  PHP has a very rich set of core libraries. In PHP, we have an array of functions we can use to manipulate arrays in different ways without having to create a new function for specific cases. The most common array functions in PHP are: array_merge( $arrays ) — Combines two or more arrays, array_diff( $array1 , $array2 ) — Finds the difference between two arrays, array_map( $callback , $array ) — Creates an array by calling a user-defined function on every array element, array_filter( $array ) — Filters out all elements in an array that do not return true when passed to the callback function.

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