Array info, execute, run and test online

In PHPhường, array is an implementation of an ordered Map. A map is an abstract data type of key value pairs. It is an interface, a contract.Quý khách hàng đang xem: Get length array php

A bản đồ can have sầu different implementations lượt thích a HashTable, HashMap, Dictionary, etc. In PHPhường, underlying implementation of an array actually points to lớn a HashTable.

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So if you are looking for a HashTable data type in PHP, look nowhere, it is the Array itself.

To know the internals, I recommend you to go through the PHPhường. source for Array và HashTable.

You can use the array to lớn store a group of data & refer them via a single variable name. Each array thành công is stored as a key and value pair.


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Arrays are classified as “indexed array” & “associative sầu array” based on the key specification. The Indexed array has mặc định index that starts with ‘0’. The associative array contains the user-defined key index.

Keys are not restricted to lớn natural numbers. You can use strings as well.

What is inside?

How lớn create an Array in PHP? How to find the kích cỡ of a PHP.. Array? How to convert an array to a string in PHP? How khổng lồ convert a string to lớn an array in PHP? Finding intersection, difference and union of arrays Creating variables from array keys Frequently used built-in Array functions

How to lớn create an Array in PHP?

An empty array

Single dimensional array

Associative array

"Wild", "Sheep"=>"Domestic", "Tiger"=>"Wild"); // loop through associative sầu array & get key value pairs foreach($animals as $key => $value) ?>

Two dimensional array

"; } ?>

Via loop

Three dimensional array


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How khổng lồ find the size of a PHP Array?

You can use count function to find the size of an array. sizeof is an alias of the function count.

You might think what is the big giảm giá khuyến mãi with count function. If you are a beginner, you will definitely learn something new, so read on và bởi not skip this. Also rethành viên to kiểm tra the example script.

count

The syntax of PHPhường count function is,

count(var array_variable, mode)

If the value of array_variable is not mix or having an empty array, then count will return 0. And, if it is not an array, then count will return 1. In PHPhường version 7 onwards, you will get a warning.

So whenever you need to kiểm tra if a PHP. array is empty, you need lớn use the count function. Ensure that you pass array khổng lồ the count function.

0) else ?>

The argument mode is optional và it specifies the mode of operation to be used in calculating array length. Possible options are,

COUNT_NORMAL – will return the length of an array in depth 0. This is the mặc định. COUNT_RECURSIVE – for recursive sầu count operation, till it reaches depth n. This recursive gọi will be continued infinitely, till it reaches depth n or the program execution time limit is elapsed. Example: PHPhường count() with mode option

Following script is an example for count function to lớn calculate a number of elements available to lớn a depth level. Let us use a two-dimensional array so that we can specify the mode depth.

$toys = array(array("name"=>"Mechanical Cars","category"=>"pull back"), array("name"=>"Jigsaw","category"=>"puzzles"), array("name"=>"HiTech Cars","category"=>"remote"), array("name"=>"Teddy Bears","category"=>"soft"), array("name"=>"Baby pillow","category"=>"soft"), array("name"=>"Chinese Checker","category"=>"puzzles"), array("name"=>"Jumbo Helicopter","category"=>"remote"));

Now, we can invoke count function by passing different possible mode options.

$array_length = count($toys,COUNT_NORMAL); //(OR) $array_length = count($toys); $array_length = count($toys,COUNT_RECURSIVE); print "

"; print_r($array_length); print ""; In the above PHP code, the count() is invoked with normal, default and recursive sầu mode. Returned values are stored into an array named, $array_length, by specifying the appropriate name indices.

Following is the output of this program.

Array ( => 7 => 7 => 21 )

sizeof

This function sizeof is an alias of PHPhường. count function. It accepts the same phối of arguments as lượt thích as count().

We can replace the count with sizeof in the above PHP. code to compare the results of both functions which will be same for both functions calls.

Alias functions in PHP are preserved for providing backward compatibility. If you are writing a new program it is better not khổng lồ go with the alias functions as there is a chance khổng lồ deprecate it in the future.

How to convert an array to lớn a string in PHP?

You can use the built-in function implode to convert an array to lớn a string.

PHP Implode

implode function accepts an array và a separator as parameters. It combines each of the array elements và separates them with the passed separator argument. For example,

$str_concát = "|"; $meaning_array = array("implode","join","concatenate"); $imploded_string = implode($str_conmèo,$meaning_array); emang đến $imploded_string; // implode|join|concatenate

If you use a comma (,) as separator, then you will be able khổng lồ covert the array as CSV. This will be a useful utility in many situations.

How to lớn convert a string lớn an array in PHP?

You can use the built-in function explode lớn convert a string lớn an array. split function is deprecated và so do not use it for creating an array based on a string.

PHP.. Explode

explode is to lớn split the string into lớn an array of elements based on a given separator. explode accepts separator và a string as its argument.

$input_string = "implode|join|concatenate"; $str_explode = "|"; $exploded_array = explode($str_explode,$input_string ); emang lại "

"; print_r($exploded_array); emang lại ""; This example code accepts the resultant string data of implode example we just saw above sầu. Explode splits string data based on the argument separator “|”. The output is,

Array ( => implode => join => concatenate ) Explode within Limit

PHPhường explode() accepts a third optional argument limit to set target length or boundary for performing explode operation. explode will take entire string as mặc định if limit is not specified.

$exploded_array = explode($str_explode,$input_string,2);

this will return,

Array ( => implode => join|concatenate )

Finding intersection, difference và union of arrays

PHPhường has wide array of in-built functions for handling arrays. Intersection, difference và union are performed quite regularly when using arrays. PHP has got good mix of functions in-built khổng lồ handle these operations.


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Array intersection

PHPhường. array_intersect function is used to lớn find intersection between arrays. This function can accept multiple arguments lớn compare. After comparison, this function returns an array of intersecting elements that are present in all the argument arrays.

Syntax:

array_intersect($input_array1,$input_array2,$input_array3...) Array intersection example "; print_r($arrayIntersect); print ""; ?>

This program prints resultant array containing values that are present in all the four input đầu vào arrays. The output is,

Array( => Baby Pillow => Teddy Bear ) Other Array intersection functions in PHP

PHP includes more variety of functions khổng lồ calculate intersection of elements among input đầu vào arrays.

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array_intersect_key – returns intersecting elements with respect lớn the keys. array_interset_assoc – returns intersecting elements with respect to lớn keys & values. array_intersect_ukey – returns intersecting elements on the basis of custom function by providing an algorithm for the intersection.

Array difference

By using PHPhường array difference functions, we can find differences between arrays with respect lớn their keys or values.

array_diff array_diff_key array_diff_assoc

Array differences can also be found, based on the index check by using the custom made functions. They are used as a callbaông chồng.

array_diff_ukey array_diff_uassoc

The các mục goes on. By comparing their entries with the use of user-defined callback functions.

array_udiff array_udiff_assoc array_udiff_uassoc array_diff

It accepts at least two arrays, but, maximum in any number of arrays, as its arguments, thereby, the elements from the first array will be compared with the rest of the array elements.

array_diff_key

This function is used as similar as array_diff, but for comparing array elements with respect to their key.

array_diff_assoc

This function is used khổng lồ compare the values between given arrays, by considering the key index associated with these values.

Array difference example "apple", "fruit2" => "grapes","friut3" =>"banana"); $array_against = array("fruit1" => "orange", "fruit2" => "grapes","friut4" => "banana"); $value_differences = array_diff($array_from, $array_against); $key_differences = array_diff_key($array_from, $array_against); $assoc_index_differences = array_diff_assoc($array_from, $array_against); print ""; print_r($value_differences); print_r($key_differences); print_r($assoc_index_differences); print ""; ?>

Array difference example’s output below:

Array ( => táo khuyết ) Array ( => banamãng cầu ) Array ( => táo bị cắn => banamãng cầu ) PHPhường Array difference with callback – closures

It is possible lớn define your own custom xúc tích và ngắn gọn to find difference between arrays. User-defined functions can be passed for callbaông chồng.

Passing functions as argument is a cool feature in PHP. They are called anonymous functions and implemented using closures.

array_diff_ukey , array_diff_uassoc for key and index based differences. array_udiff , array_udiff_assoc for value based array difference. array_udiff_uassoc used to persize both array value và key index comparison.

Creating variables from array keys

PHPhường. has a function named extract khổng lồ create variables using array keys. It creates PHPhường variables with the name of each array keys. It uses an associative sầu array as input đầu vào argument.

extract

This function accepts three arguments as listed below.

$input_array – Associative array from which the keys are converted into PHPhường variables. $extract_type – Defines options to lớn create a new variable or overwrite existing variables. EXTR_OVERWRITE, EXTR_SKIP., EXTR_IF_EXISTS, EXTR_REFS are the options. $variable_prefix – String to prefix with the variable name lớn be created. PHPhường extract example "Stories","partB" => "Rhymes", "partC" => "Concepts"); extract($input_array,EXTR_OVERWRITE); print "$partA=". $partA . ""; print "$partB=". $partB . ""; print "$partC=". $partC . ""; ?> Caution on using extract

You should not use extract on user đầu vào data. If you bởi vì so, it may cause security concerns. Do not use this function, unless otherwise you know what you are doing!

Frequently used built-in Array functions

Let us see some of the widely used PHP. array functions with PHP code snippet examples.

range

PHPhường range() function is used get the array of elements in the range between the start and end parameters. The range can be a numeric or alphabet. The following code shows how to get the array of alphabets that exists between “e” và “i”.

$character_array = range("e","i"); // returns array("e","f","g","h","i");

reset

The reset() function is used khổng lồ reset the position of the array pointer. It requires the array variable as its argument, lớn move the array pointer to its original position.

$character_array = range("e","i"); // returns array("e","f","g","h","i"); print next($character_array); // prints f print next($character_array); // prints g reset($character_array); print current($character_array); // prints the first element "e" after rephối

array_slice

It is used to get the sub-array from the given input array. It accepts the input array, starting position as offmix & the length of the sub array.

The length parameter is optional. If it is not specified, the length of the input array will be taken by mặc định. The fourth argument is to lớn preserve keys by avoiding the default index reordering behavior.

$color_array = array("Red","Blue","Green","Yellow","Brown"); sliced_array = array_slice($color_array,1,3);// now the sliced array will be array("Blue","Green","Yellow")

array_splice

This function is similar to array_slice & it can also replace the removed elements with the new phối of elements. The length of the removed mix and new array should be same.

$character_array = array("e","f","g","h","i"); $number_array = array("1","2","3"); $changed_array = array_splice($character_array,1,3,$number_array); // will hold the element like: array("e","1","2","3","i");

shuffle

This function has the array as an argument to change the position of its value in a random manner.

array_chunk

array_chunk() is used lớn break an array into lớn the specified length of chunks.

$character_array = array("e","f","g","h","i"); $chunks = array_chunk($character_array,2); //$chunks will be as follows /* Array ( => Array ( => e => f ) => Array ( => g => h ) => Array ( => i ) ) */

merge

merge function, is for joining one or more arrays into lớn a single array.

$color_array1 = array("Red","Blue","Green"); $color_array2 = array("Yellow","Brown"); // returns array("Red","Blue","Green","Yellow","Brown"); $color_array = array_merge($color_array1,$color_array2);

array_key_exists

This function is used to kiểm tra whether the given key exists in the array or not. This function takes a key element và the input đầu vào array as arguments.

array_keys, array_values

These two functions will return the keys and values of an input array, respectively. The following code shows the usage method of these functions & the resultant array of keys & values.

$student_array = array("name"=>"Martin","mark"=>"90","grade"=>"A"); $key_array = array_keys($student_array) // returns array("name","mark","grade") $value_array = array_values($student_array) // returns array("Martin","90","A")

array_push, array_pop, array_shift, array_unshift

array_push() is used to lớn push values inlớn an array. Using this function, a new element will be added lớn the kết thúc of a given đầu vào array.

The array_pop() is used khổng lồ get the last element of the array.

The array_shift() & the array_unshift() methods are as similar as array_push() & array_pop()But, the insert và retrieve sầu operations are performed at the starting position of the array.

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extract, compact

The example shows it as follows. The second & third argument of extract() is optional. It is used to add a prefix khổng lồ the variable name.

$student_array = array("name"=>"Martin","mark"=>"90","grade"=>"A"); extract($student_array,EXTR_PREFIX_ALL,"student"); eđến $student_name . "-" . $student_mark . "(" . $student_grade . ")"; // prints as Martin - 90(A) $compact_array = compact("student_name","student_mark","student_grade"); // will form an array Chuyên ổn mục:

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