Summary of commonly used array functions in PHP

Compiled a comprehensive 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, and other arrays functions etc.

1. Basic functions of array operations

The key name and value of the array

array_values($arr); Obtain the array The value of
array_keys($arr); Get the key name of the array
array_flip($arr); The value in the array is interchanged with the key name (if there are duplicates, the previous one will be overwritten by the later one)
in_array ("apple",$arr); Search for apple in the array
array_search("apple",$arr); Search for apple in the array and return the key name if it exists
array_key_exists("apple",$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($arr); Returns the key name of the current unit in the array
prev($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 one Unit
reset($arr; points the internal pointer in the array to the first unit
each($arr); will return a constructed array of key names/values ​​of the current element of the array, and move the array pointer forward Move one bit
list($key,$value)=each($arr); Get 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 the variable value
Note: (The second parameter is very important, you can refer to the manual for use) Use Method echo $a;
compact(var1,var2,var3);Creates an array with the given variable name

2. Array segmentation and filling

Segmentation of array

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

Filling of the array

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

3. Array and Stack

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

4. Arrays and queues

array_shift($arr);The first element in the array is moved out and returned as the result (the length of the array is reduced by 1, other elements are moved forward by one position, the numeric key name is changed to zero, and the text key name remains unchanged)
array_unshift($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, If the callback function is TRUE, the current element of the array will be included in the returned result array, and the key names of the array will remain unchanged
array_reduce($arr,"function","*"); converted into a single-valued function ( * is the first value of the array)

6. Sorting of the array

Sort the array by element value

sort($arr); Sort in order from small to large (the second parameter is how to sort) Array sorting ignoring key names
rsort($arr); Sort in order from large to small (the second parameter is how to sort) ) Array sorting ignoring key names
usort($arr,"function"); Use a user-defined comparison function to sort the values ​​in the array (there are two parameters in the function, 0 means equal, and a positive number means the first One is greater than the second, a negative number means the first is less than the second) Array sorting ignoring the key name
asort($arr); Sort from small to large (the second parameter is how to sort) Array sorting with key names preserved
arsort($arr); Sorting from large to small (the second parameter is the sorting method) Array sorting with key names preserved
uasort($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 is greater than the second, a negative number means the first is less than the second) reserved Array sorting of key names

Sort the array by key names

ksort($arr); Sort by key names in positive order
krsort($arr); Sort by key names in reverse order
uksort($arr,"function"); Use a user-defined comparison function to sort the keys 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, Negative number means the first one is smaller 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 one overwrites the previous one, the same numeric key name, the latter one will not be overwritten, 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 there are the same string key names in the array, 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($arr1,$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 the arrays

array_intersect($ arr1,$arr2); Returns the intersection result array

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

8. Other array functions

range(0,12); Create an array containing the specified range of cells

array_unique($arr); Remove duplicate values ​​in the array, and the original key names will be retained in the new array

array_reverse($arr,TRUE); Returns an array with the order of cells reversed to the original array. If the second parameter is TRUE, the original key name is retained.
//srand((float)microtime()*10000000); Random Seed trigger
array_rand($arr,2); Randomly remove one or more elements from the array
shuffle($arr); Shuffle the order of the array

This class of functions allows Multiple ways to manipulate 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 processing functions that generate arrays from database queries, and there are functions that return arrays.

array_change_key_case — Returns an array whose string keys are all lowercase or uppercase

array_chunk — Splits an array into multiples

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

array_count_values ​​— Count the number of occurrences of all values ​​in the array

array_diff_assoc — Compute the difference of an array with index checking

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

array_diff_uassoc — Compute the difference of an array with an index check using a user-supplied callback function

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

array_diff — Calculate the difference set of arrays

array_fill_keys — Fill an array with values, specifying keys

array_fill — fills an array with given values ​​

array_filter — uses a callback function to filter elements in an array

array_flip — swaps keys and values ​​in an array

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, compares the indices with a callback function

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 the array with values ​​to the specified length

array_pop — Pop the last element of the array

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

array_push — Push one or more elements to the end of the array (push)

array_rand — Take a random element from the array or multiple cells

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

array_reverse — Return an array with the cells in reverse order

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

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

array_slice — Remove a segment from the array

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

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

array_udiff_assoc — Calculate the difference of an array with index checking, compare data using callback functions

array_udiff_uassoc — Computes the difference of an array with index checking, using a callback function to compare data and indexes

array_udiff — Computes the difference of an array using a callback function to compare data

array_uintersect_assoc — With indexing Check to calculate intersection of arrays, compare data using callback function

array_uintersect_uassoc — Check to calculate intersection of arrays with index, use callback function to compare data and index

array_uintersect — Calculate intersection of arrays, use callback function Compare data

array_unique — Remove duplicate values ​​in an array

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

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

array_walk_recursive — Recursively applies a user function to each member of an array

array_walk — Applies a user function to each member of an array

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 — Extracts the array pointer from the array Import variables into the current symbol table

in_array — Check whether a certain value exists in the array

key — Get the key name from the associative array

krsort — Sort the array according to the key Name reverse sort

ksort — Sort the array by key name

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

natcasesort — Use the “natural sort” algorithm to sort the array Perform a case-insensitive sort

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

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

pos — Alias ​​for current()

prev — Rewind the internal pointer of an array by one position

range — Create an array containing cells in the specified range

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

rsort — Sort the array in reverse order

shuffle — Shuffle an array

sizeof — Alias ​​for count()

sort — Sort an array

uasort — Use a user-defined comparison function to compare values ​​in an array Sort and maintain index correlation

uksort — Sort the keys in an array using a user-defined comparison function

usor — Sort the values ​​in an array using a user-defined comparison function

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