Summary of common functions for PHP arrays

                                                       

1. Basic functions of array operations

Key name and value of array

array_values($arr) ; Get the value of the array
array_keys($arr); Get the key name of the array
array_flip($arr); Exchange the values ​​and key names in the array (if there are duplicates, the previous one will be overwritten by the later one)
in_array(“apple”,$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($arr); Returns the key name of the current unit in the array
prev ($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); Move the internal pointer in the array Point to the last unit
reset($arr; Point the internal pointer in the array to the first unit
each($arr); Will return a constructed array of key names/values ​​of the current element of the array, and make the array Move the pointer forward one position (repeated in php7)
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, please refer to the manual for use) Use the method echo $a;
compact(var1,var2,var3); to create an array with the given variable name

2. Segmentation of the array Fill in the segments of the

array

array_slice($arr,0,3); You can take out a segment of the array, this function ignores the key name
array_splice($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 ones. TRUE retains 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($arr,"apple","pear ”); Push one or more elements to the end of the array stack (push), and return the number of elements pushed into the stack
array_pop($arr); Pop the last element of the array stack (pop)

4. Arrays and Queues

array_shift($arr); The first element in the array is moved out and returned as the result (the length of the array is reduced by 1, and other elements are moved forward One bit, the numeric key name is changed to zero technology, the text key name remains unchanged)
array_unshift($arr,"a",array(1,2));Insert one or more elements at the beginning of the array

5. Callback function

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

6. Sorting of arrays

Sort the array by element value

sort($arr); Sort from small to large (the second parameter is how to sort) Array sorting ignoring key names
rsort($arr ; Sort by value (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) Array sorting ignoring key names
asort($arr) ; Sort from small to large (the second parameter is how to sort). Sort the array with key names
arsort($arr); Sort from large to small (the second parameter is how to sort) Sorting) Array sorting that preserves key names
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, positive number means The first is greater than the second, a negative number means the first is less than the second) Array sorting that preserves key names

Sort the array by key name

ksort($arr); Sort by key name in positive order
krsort($arr); Sort by key name in reverse order
uksort($arr," function"); Use a 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 is greater than the second, a negative number means the first is less than the second )

Natural sorting sorting

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

7. Array calculation

Sum of array elements

array_sum($arr); Sum all the elements inside the array Operation

Merge of arrays

array_merge($arr1,$arr2); Merge two or more arrays (same string key name, the latter one overwrites the previous one, the same numeric key name, the following ones 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 the arrays have the same string key name, these values ​​will be merged into one 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 is allowed 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 multiple

array_combine — Creates an array, using an array The value of another array is used as its key name, and the value of another array is used as its value

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

array_diff_assoc — Calculate the difference set of the array with index check

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 callback function for index checking

array_diff_ukey — Uses a callback function to Compare key names to calculate the difference of an array

array_diff — Calculate the difference of an array

array_fill_keys — Fill an array with values, specifying keys

array_fill — Use the given value Populate an array

array_filter — Filter elements in an array using a callback function

array_flip — Swap the keys and values ​​in an array

array_intersect_assoc — Compute the intersection of arrays with index checking

array_intersect_key — Computes the intersection of arrays using key comparisons

array_intersect_uassoc — Computes the intersection of arrays with index checking, using callback functions to compare indices

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

array_intersect — Calculate the intersection of arrays

array_key_exists — Check whether the given key name or index exists in the array

array_keys — Return all the keys in the array Key

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 Array

array_multisort — Sort multiple arrays or multidimensional arrays

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

array_pop — Pop (out) the last element of an array stack)

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 — From an array Randomly pick out one or more cells from

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

array_reverse — Return an array with the cells in the reverse order

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

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 the data with a callback function

array_udiff_uassoc — Calculate the difference of an array with index checking , use callback function to compare data and index

array_udiff — use callback function to compare data to calculate the difference of arrays

array_uintersect_assoc — use index check to calculate the intersection of arrays, use callback function to compare data

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

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

array_unique — Remove arrays Repeated values ​​in

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

array_values ​​— Return all values ​​in the array

array_walk_recursive — For each member of the array Recursively apply the user function

array_walk — Apply the user function to each member of the array

array — Create a new array

arsort — Sort the array in reverse order and maintain the index Relation

asort — Sort an array while maintaining index relationships

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

count — Count the number of cells in an array or Number of properties in the object

current — Returns the current element in the array

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

end — Point the internal pointer of the array to the last element

extract — Import variables from the array into the current symbol table

in_array — Check whether a value exists in the array

key — Get the key name from the associative array

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

ksort — Sort the array by the key name

list — Put The values ​​in the array are assigned to some variables

natcasesort — Sort the array in a case-insensitive manner using the “natural sort” algorithm

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

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

pos — Alias ​​for current()

prev — Moves the internal pointer back one position in the array

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 sort the 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 Sorting

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