What are the commonly used array functions in PHP? Summary of commonly used array functions in PHP

PHP Arrays are an essential part of PHP, and the array function also plays a very important role. This article has compiled a complete list of array operations in PHP development, including basic functions of array operations, array segmentation and Filling, arrays and stacks, arrays and queues, callback functions, sorting, calculations, other array functions, etc.

1. Basic functions of array operations

Array key names and values

array_values($arr); Get the value of the array
array_keys($arr); Get the key name of the array
array_flip($arr); Exchange the values ​​and key names in the array (if there are duplicates, the previous ones will Overwritten by the latter)
in_array("apple",$arr); Retrieve apple in the array
array_search("apple",$arr); Retrieve apple in the array, if it exists, return the key name
array_key_exists("apple",$arr); Retrieve whether the given key name exists in the array
isset($arr[apple]): Retrieve whether the given key name exists in the array

Internal pointer of the array

current($arr); Returns the current unit in the array
pos($arr); Returns the current unit in the array
key($arr); Return the key name of the current unit in the array
prev($arr); Move the internal pointer in the array back one bit
next($arr); Move the internal pointer in the array forward one bit
end($arr); Point the internal pointer in the array to the last unit
reset($arr; Point the internal pointer in the array to the first unit
each($arr); Will return the current element of the array Construct an array of key names/values ​​and move the array pointer forward one bit
list($key,$value)=each($arr); Obtain the key name and value of the current element of the array

Conversion between arrays and variables

extract($arr); is used to convert the elements in the array into variables and import them into the current file. The key name is used as the variable name and the value is used as Variable value
Note: (The second parameter is very important, you can refer to the manual for use) Use the method echo $a;
compact(var1,var2,var3);Create an array with the given variable name

2. Array segmentation and filling

·Array segmentation

array_slice($arr,0,3); You can take out a section from the array. This function ignores the key name
array_splice($arr,0,3,array("black","maroon")); You can take out a section from the array, which is different from the previous function. The returned sequence is deleted from the original array

·Split multiple arrays

array_chunk($arr,3,TRUE); You can split an array into multiple , TRUE is to retain the key names of the original array

·Filling of the array

array_pad($arr,5,'x'); Fill an array to the specified length

3. Arrays and stacks

array_push($arr,"apple","pear"); Push one or more elements to the end of the array stack ( Push), return the number of pushed elements
array_pop($arr); Pop (pop) the last element of the array stack

4. Arrays and queues

array_shift($arr); The first element in the array is moved out and returned as the result (the length of the array is reduced by 1, other elements are moved forward one position, the numeric key name is changed to zero technology, and the text key name is not Change)
array_unshift($arr,"a",array(1,2));Insert one or more elements at the beginning of the array

5. Callback function

array_walk($arr,'function','words'); Use user function to process each member in the array (the third parameter is passed to the callback function function)
array_mpa("function", $arr1,$arr2); Can handle multiple arrays (when using two or more arrays, their lengths should be the same)
array_filter($arr,"function"); Use the callback function to filter each element in the array elements, if the callback function is TRUE, the current element of the array will be included in the returned result array, and the key name of the array remains unchanged
array_reduce($arr,"function","*"); Convert to single Value function (* is the first value of the array)

Related recommendations: "php introductory tutorial"

6. Sorting of arrays

·Sort array by element value

sort($arr); Sort from small to large (the second parameter is how to sort), ignore the key name array sorting
rsort($arr); Sort from large to small ( The second parameter is how to sort) Array sorting ignoring key names
usort($arr,"function"); Use user-defined comparison function to sort the values ​​​​in the array (there are two parameters in the function , 0 means equal, a positive number means the first one is greater than the second one, a negative number means the first one is less than the second one) Array sorting ignoring the key name
asort($arr); Sort from small to large (No. The second parameter is how to sort) Array sorting with key names preserved
arsort($arr); Sort from large to small (the second parameter is how to sort) Array sorting with key names preserved
uasort($arr,"function"); Use a user-defined comparison function to sort the values ​​in the array (there are two parameters in the function, 0 means equal, a positive number means the first one is greater than the second one, a negative number means The first is smaller than the second) Array sorting with key names preserved

· Sort the array by key name

ksort($arr); In positive order of key names Sort
krsort($arr); Sort by key name in reverse order
uksort($arr,"function"); Use user-defined comparison function to sort the key names in the array (there are two parameters in the function , 0 means equal, a positive number means the first one is greater than the second one, a negative number means the first one is less than the second one)

·Natural sorting method

natsort ($arr); Natural sorting (ignore key names)
natcasesort($arr); Natural sorting (ignore case, ignore key names)

7. Array calculations

·Sum of array elements

array_sum($arr); Perform sum operation on all elements inside the array

·Merge of arrays

array_merge($arr1,$arr2); Merge two or more arrays (the same string key name, the latter overwrites the previous one, the same numeric key name, the latter does not The overwriting operation will be performed, but appended to the end)
“+”$arr1+$arr2; For the same key name, only the last one is retained
array_merge_recursive($arr1,$arr2); Recursive merge operation, if in the array With the same string key, these values ​​will be merged into an array. If a value itself is an array, it will be merged into another array according to the corresponding key name. When arrays have the same array key name, the latter value will not overwrite the original value, but will be appended to the difference set of the following

·array_diff

array_diff ($arr1,$arr2); Returns the difference set result array
array_diff_assoc($arr1,$arr2,$arr3); Returns the difference set result array, and the key names are also compared

·Intersection of arrays

array_intersect($arr1,$arr2); Returns the intersection result array
array_intersect_assoc($arr1,$arr2); Returns the intersection result array, and the key names are also compared

8. Other array functions

range(0,12); Create an array containing cells in the specified range
array_unique($arr); Remove duplicates in the array value, the original key names will be retained in the new array
array_reverse($arr,TRUE); Returns an array with the unit order opposite to the original array, if the second parameter is TRUE, the original key names will be retained
/ /srand((float)microtime()*10000000); Random seed trigger
array_rand($arr,2); Randomly remove one or more elements from the array
shuffle($arr); Order shuffling

This class of functions allows multiple methods to operate and interact with arrays. The essence of an array is to store, manage and operate a set of variables.

PHP supports one- and multi-dimensional arrays, which can be created by the user or by another function. There are specific database handling functions that generate arrays from database queries, and there are functions that return arrays.

The following is a summary of some related usages of the array function:

array_change_key_case - Returns an array with all string key names in lowercase or uppercase

array_chunk — Split an array into multiple

array_combine — Create an array with the value of one array as its key name and the value of another array as its value

array_count_values ​​— Count all items in the array Number of occurrences of a value

array_diff_assoc — Computes the difference of an array with index checking

array_diff_key — Computes the difference of an array using key name comparison

array_diff_uassoc — Computes the difference of an array using a user-supplied The callback function does index checking to calculate the difference of the array

array_diff_ukey — Use the callback function to compare the key names to calculate the difference of the array

array_diff — Calculate the difference of the array

array_fill_keys — Fill an array with values, specifying keys

array_fill — Fill an array with given values

array_filter — Filter elements in an array with a callback function

array_flip — Swap Keys and values ​​in arrays

array_intersect_assoc — Computes the intersection of arrays with index checking

array_intersect_key — Computes the intersection of arrays using key name comparison

array_intersect_uassoc — Computes the intersection of arrays with index checking intersection, use callback function to compare index

array_intersect_ukey — Calculate the intersection of arrays using callback functions to compare keys

array_intersect — Calculate the intersection of arrays

array_key_exists — Check whether a given key or index exists in an array

array_keys — Returns all keys in the array

array_map — Apply the callback function to the cells of the given array

array_merge_recursive — Recursively merge one or more arrays

array_merge — merge one or more arrays

array_multisort — sort multiple arrays or multidimensional arrays

array_pad — pad an array with values ​​to a specified length

array_pop — Pop the last element of the array (pop it off the stack)

array_product — Calculate the product of all values ​​in the array

array_push — Push one or more elements to the end of the array (put it on the stack) stack)

array_rand — Randomly remove one or more elements from an array

array_reduce — Use a callback function to iteratively reduce an array to a single value

array_reverse — Return a Array with cells in reverse order

array_search — Search for a given value in the array, and return the corresponding key name if successful

array_shift — Move the cell at the beginning of the array out of the array

array_slice — Remove a segment from an array

array_splice — Remove a portion of an array and replace it with another value

array_sum — Calculate the sum of all values ​​in an array

array_udiff_assoc — With Index check calculates the difference of an array, using a callback function to compare the data

array_udiff_uassoc — Calculate the difference of an array with an index check, using a callback function to compare the data and index

array_udiff — Use a callback function to compare the data To calculate the difference of arrays

array_uintersect_assoc — Calculate the intersection of arrays with index checking, use callback function to compare data

array_uintersect_uassoc — Calculate the intersection of arrays with index checking, use callback function to compare data and index

array_uintersect — Calculate the intersection of arrays, compare data using callback functions

array_unique — Remove duplicate values ​​in an array

array_unshift — Insert one or more cells at the beginning of the array

array_values ​​— Returns all values ​​in an array

array_walk_recursive — Applies a user function recursively to each member of an array

array_walk — Applies to each member of an array User function

array — Create a new array

arsort — Sort the array in reverse and maintain the index relationship

asort — Sort the array and maintain the index relationship

compact — Create an array, including variable names and their values ​​

count — Count the number of cells in the array or the number of attributes in the object

current — Return the current cell in the array

each — Returns the current key/value pair in the array and moves the array pointer one step forward

end — Points the array’s internal pointer to the last element

extract — From Import variables into the current symbol table in the array

in_array — Check whether a certain value exists in the array

key — Get the key name from the associative array

krsort — Right Sort the array in reverse order by key name

ksort — Sort the array by key name

list — Assign the values ​​in the array to some variables

natcasesort — Use "natural sorting" Algorithm for case-insensitive sorting of an array

natsort — Sorts an array using the “natural sort” algorithm

next — Moves the internal pointer in the array forward one position

pos — Alias ​​for current()

prev — Rewind the internal pointer of the array by one bit

range — Create an array containing cells in the specified range

reset — Point the internal pointer of the array to the first element

rsort — Reverse sort the array

shuffle — Shuffle the array

sizeof — Alias ​​of count()

sort — Sort an array

uasort — Use a user-defined comparison function to sort values ​​in an array and maintain index association

uksort — Use a user-defined comparison function Sort the key names in the array

usort — Use user-defined comparison function to sort the values ​​​​in the array

The above is the arrangement of the array function in the PHP array. I hope you can pass this This article has a more comprehensive understanding of the array function.

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