Summary of commonly used array functions in PHP

This article mainly share with you the PHP common Array function Summary. We will be divided into six parts to share with you, the first part is the basic function of array operation, the second part is the array of fragments and fills, the third part is ...

The key name and value of the array

Array_values ($arr); Get the value of an array
Array_keys ($arr); Get the key name of the array
Array_flip ($arr); The values in the array are interchanged with the key names (if there are duplicates, the previous overrides will be followed)
In_array ("Apple", $arr); Retrieving an apple in an array
Array_search ("Apple", $arr); Retrieve Apple in an array if there is a return key name
Array_key_exists ("Apple", $arr); Retrieves whether the given key name exists in the array
Isset ($arr [Apple]): Retrieves whether the given key name exists in the array

An internal pointer to an array

Current ($arr); Returns the current cell in the array
POS ($arr); Returns the current cell in the array
Key ($arr); Returns the key name of the current cell in the array
Prev ($arr); Returns the internal pointer in the array back to a
Next ($arr); Moves the inner pointer in the array forward one
End ($arr); Point the inner pointer in the array to the last cell
Reset ($arr; point the inner pointer in the array to the first cell
each ($arr); Constructs an array that returns a key name/value of the current element of the array and moves the array pointer forward one
List ($key, $value) =each ($arr); Gets the key name and value of the current element of the array

Conversions between arrays and variables

Extract ($arr); used to convert an element in an array into a variable and import it into the current file, the key name as the variable name, and the value as the variable value
Note: (The second parameter is very important, can see the manual use) method of use echo $a;
Compact (VAR1,VAR2,VAR3); Create an array with the given variable name

Ii. segmentation and padding of arrays

Fragment of an array

Array_slice ($arr, 0, 3); You can take a paragraph out of the array, and this function ignores the key name
Array_splice ($arr, 0,3,array ("Black", "maroon")); You can take a paragraph out of an array, unlike the previous function, in which the returned sequence is removed from the original array.

Splitting multiple arrays

Array_chunk ($arr, 3,true); You can split an array into multiple, true to preserve the key name of the original array

Padding of arrays

Array_pad ($arr, 5, ' X '); Fills an array into a set length

Three, arrays and stacks

Array_push ($arr, "apple", "pear"); Presses one or more elements into the end of the array stack (into the stack), returning the number of elements in the stack
Array_pop ($arr); POPs the last element of the array stack (out of the stack)

Iv. Arrays and queues

Array_shift ($arr); The first element in the array is moved out and returned as a result (array length minus 1, other elements move forward one bit, number key name changed from zero technology, text key name unchanged)
Array_unshift ($arr, "a", array); inserts one or more elements at the beginning of the array

Five, callback function

Array_walk ($arr, ' function ', ' words '); Use the user function to process each member in the array (the third argument is passed to the callback function)
Array_mpa ("function", $arr 1, $arr 2); can handle multiple arrays (they should be the same length when two or more arrays are used)
Array_filter ($arr, "function"); Using a callback function to filter each element in the array, if the callback function is true, the current element of the array is 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 (* The first value of an array)

Vi. Ordering of arrays

Sort by array of element values

Sort ($arr); Sort from small to large (the second parameter is sorted by what sort) ignores the array ordering of the key names
Rsort ($arr); Sort by large-to-small order (the second argument is sorted by what sort) ignores the array ordering of the key names
Usort ($arr, "function"); Use a user-defined comparison function to sort the values in the array (there are two parameters in function, 0 for equality, positive for the first greater than the second, negative for the first less than the second) to sort the arrays with the key names ignored
Asort ($arr); Sort by order of small to large (the second parameter is sorted by what sort) the array of reserved key names
Arsort ($arr); Sort by order of large to small (the second parameter is sorted by what sort) the array of reserved key names
Uasort ($arr, "function"); Use a user-defined comparison function to sort the values in the array (function with two parameters, 0 for equality, positive for the first one greater than the second, negative for the first one less than the second) to sort the arrays of reserved key names

Sort arrays by key names

Ksort ($arr); Sort by key name in a positive order
Krsort ($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 function, 0 for equality, positive for the first greater than the second, and negative for the first less than the second one)

Sort by natural sort

Natsort ($arr); Natural sort (ignores key names)
Natcasesort ($arr); Natural sort (ignores case, ignores key name)

Vii. Calculation of arrays

Sum of array elements

Array_sum ($arr); Sums all elements inside an array

Merging of arrays

Array_merge ($arr 1, $arr 2); Merge two or more arrays (the same string key name, followed by overwriting the previous, same numeric key name, followed by no overwrite operation, but appended to the back)
"+" $arr 1+ $arr 2; For the same key name, keep only the latter one
Array_merge_recursive ($arr 1, $arr 2); Recursive merge operations, if the array has the same string key name, these values will be merged into an array. If a value is itself an array, it will be merged into another array according to the corresponding key name. When the array has the same array key name, the latter value will not overwrite the original value, but append to the back

The difference set of an array

Array_diff ($arr 1, $arr 2); Returns an array of difference results
ARRAY_DIFF_ASSOC ($arr 1, $arr 2, $arr 3); Returns the array of difference results, and the key names are also compared

Intersection of arrays

Array_intersect ($arr 1, $arr 2); Returns an array of intersection results
ARRAY_INTERSECT_ASSOC ($arr 1, $arr 2); Returns an array of intersection results, with key names also being compared

Eight, other array functions

Range (0,12); Creates an array containing the specified range of cells
Array_unique ($arr); Removes duplicate values from the array, preserving the original key names in the new arrays
Array_reverse ($arr, TRUE); Returns an array whose cell order is reversed from the original array if the second argument is true to preserve the original key name
Srand (float) microtime () *10000000); Random seed Trigger
Array_rand ($arr, 2); Randomly fetching one or more elements from an array
Shuffle ($arr); Disturb the order of the arrays

This class of functions allows you to manipulate arrays and interact with them in a variety of ways. The essence of an array is to store, manage, and manipulate a set of variables.

PHP supports one-dimensional and multidimensional arrays that can be created by the user or created by another function. There are certain database processing functions that can generate arrays from database queries, and some functions return arrays.

array_change_key_case-returns an array of string key names that are all lowercase or uppercase

array_chunk-splits an array into multiple

Array_combine-creates an array with the value of an array as its key name, and the value of another array as its value

array_count_values-the number of occurrences of all values in the statistics array

array_diff_assoc-with index Check the difference set of the computed array

array_diff_key-Calculating the difference set of an array using the key name comparison

array_diff_uassoc-uses the user-supplied callback function to do an index check to calculate the difference set of the array

array_diff_ukey-using a callback function to compare the difference set of an array to a key name

array_diff-Calculating the difference set of an array

Array_fill_keys-fill an array with values, specifying keys

array_fill-fills an array with the given value

array_filter-filter cells in an array with callback functions

Array_flip-exchanging keys and values in an array

array_intersect_assoc-with index Check the intersection of computed arrays

array_intersect_key-calculating the intersection of an array using the key name comparison

array_intersect_uassoc-with index Check the intersection of computed arrays, using callback function to compare indexes

Array_intersect_ukey-computes the intersection of an array using a callback function to compare the key names

Array_intersect-computes the intersection of an array

array_key_exists-checks whether the given key name or index exists in the array

array_keys-returns all the key names in the array

Array_map-the callback function to the cell of the given array

array_merge_recursive-to merge one or more arrays recursively

array_merge-merging one or more arrays

array_multisort-to sort multiple arrays or multidimensional arrays

Array_pad-fills an array to a specified length with a value

array_pop-pops the last cell of the array (out of the stack)

Array_product-computes the product of all values in an array

array_push-pressing one or more cells into the end of the array (into the stack)

array_rand-random extraction of one or more cells from an array

array_reduce-iteratively to simplify the array to a single value with a callback function

array_reverse-returns an array of cells in reverse order

array_search-searches for the given value in the array, and returns the corresponding key name if successful

Array_shift-moves the cell at the beginning of the array to a group

array_slice-remove a paragraph from an array

array_splice-remove part of the array and replace it with other values

Array_sum-computes the and of all values in the array

array_udiff_assoc-with index Check the difference set of the computed array, using the callback function to compare the data

array_udiff_uassoc-with index Check to calculate the difference of the array, compare the data and index with the callback function

array_udiff-comparing data with callback functions to calculate the difference set of an array

array_uintersect_assoc-with index Check the intersection of the computed array, using the callback function to compare the data

array_uintersect_uassoc-with index Check the intersection of computed arrays, using callback functions to compare data and indexes

Array_uintersect-computes the intersection of an array, compares the data with a callback function

array_unique-duplicate values in an array

array_unshift-inserting one or more cells at the beginning of an array

array_values-returns all values in the array

array_walk_recursive-applying user functions recursively to each member in an array

array_walk-applying user functions to each member in an array

array-creating a new array

arsort-an array in reverse order and maintain an index relationship

asort-sorting an array and maintaining an index relationship

compact-create an array, including the variable names and their values

count-count the number of cells in an array or the number of properties in an object

current-returns the current cell in the array

each-returns the current key/value pair in the array and moves the array pointer forward one step

end-the inner pointer of an array to the last cell

extract-importing variables from an array into the current symbol table

in_array-checks if a value exists in the array

key-getting the key name from the associative array

krsort-an array in reverse order by key name

ksort-sorting arrays by key name

List-assigns the values in the array to some variables

natcasesort-sorting of case-insensitive letters using the "natural sort" algorithm for arrays

natsort-using the "natural sort" algorithm to sort arrays

range-creating an array containing the specified range of cells

reset-the inner pointer of an array to the first cell

rsort-reverse sequence of an array

shuffle-Array is scrambled

sort-sorting an array of arrays

uasort-use a user-defined comparison function to sort the values in the array and keep the index associated

uksort-using a user-defined comparison function to sort the key names in an array

Usort-sorts the values in the array using a user-defined comparison function