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This article mainly shares with you a summary of commonly used array functions in PHP. We will share it with you in six parts. The first part is the basic functions of array operations, the second part is the segmentation and filling of the array, and the third part is...
Key name and value of the array
array_values($arr); Get the values of the array
array_keys($arr); Get the key name of the array
array_flip($arr); Exchange the values with the key names in the array (if there are duplicates The former will be overwritten by the latter)
in_array("apple",$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); Returns the current unit in the array The key name of the current unit
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); Returns a key name of the current element of the array /Construct an array of values and move the array pointer forward one bit
list($key,$value)=each($arr); Obtain the key name and value of the current element of the array
Arrays and variables Conversion between
extract($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: (No. The two parameters are very important, you can refer to the manual for use.) Use the method echo $a;
compact(var1,var2,var3);Create an array with the given variable name
2. Segmentation of the array And fill the segment of the
array
array_slice($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"); Fill one or more Push the element to the end of the array stack (push) and return the number of elements pushed into the stack
array_pop($arr); Pop the last element of the array stack (pop off the stack)
4. Arrays and Queue
array_shift($arr);The first element in the array is moved out and returned as the result (the array length is reduced by 1, other elements are moved forward one position, the numeric key name is changed to zero technology, and the text key The 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($arr,"function"); Use the callback function to filter each element in the array, if If the callback function is TRUE, the current element of the array will be included in the returned result array, and the key names of the array will remain unchanged
array_reduce($arr,"function","*"); Convert to a single-valued function (* is the first value of the array)
6. Sorting of the array
Sort the array by element value
sort($arr); Sort from small to large (The second parameter is how to sort) Ignore the array sorting of key names
rsort($arr); Sort from large to small (The second parameter is how to sort) Ignore the array sorting of key names
usort($arr,"function"); Use a user-defined comparison function to sort the values in the array (there are two parameters in the function, 0 means equal, a positive number means the first one is greater than the second one, Negative number means the first one is smaller than the second one) Ignore the array sorting of key names
asort($arr); Sort from small to large (the second parameter is the sorting method) Keep the array sorting of key names
arsort($arr); Sort from large to small (the second parameter is how to sort). Array sorting with key names preserved.
uasort($arr,"function"); Use user-defined The comparison function sorts 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) Array sorting preserving key names
Sort array by key name
ksort($arr); Sort by key name in positive order
krsort($arr); Sort by key name in reverse order
uksort($arr,"function"); Use user-defined comparison function Sort the key names in the array (there are two parameters in the function, 0 means equal, a positive number means the first is greater than the second, a negative number means the first is less than the second)
Natural sorting method sorting
natsort($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 will be 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,$arr2); Returns the intersection result array, the key names are also compared
8. Other array functions
range(0,12); Create an array containing the specified range of units
array_unique($arr); Remove duplicate values in the array, and the original key names will be retained in the new arrayarray_reverse($arr, TRUE); Returns an array in which the order of cells is reversed from the original array. If the second parameter is TRUE, the original key name is retained
//srand((float)microtime()*10000000); Random seed trigger
array_rand($arr,2); Randomly remove one or more elements from the array
shuffle($arr); Shuffle the order of the array
This type of function allows multiple methods to operate the array and interact with it. 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.
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 the 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 the array to the specified length with values
array_pop — Pop the last element of the array out 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 take 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, use a callback function to compare the data
array_udiff_uassoc — Calculate the difference of an array with an index check, use a callback function to compare the data and index
array_udiff — Calculate the difference of arrays by comparing data with a callback function
array_uintersect_assoc — Calculate the intersection of arrays with index checking, compare data with a callback function
array_uintersect_uassoc — Calculate the intersection of arrays with index checking, use Callback function compares data and index
array_uintersect — Calculates the intersection of arrays, compares data with callback function
array_unique — Removes duplicate values in the array
array_unshift — At the beginning of the array Insert one or more cells
array_values — Returns all values in an array
array_walk_recursive — Recursively applies a user function to each member of an array
array_walk — Recursively applies a user function to each member of an array Apply user functions to each member in
array — Create a new array
arsort — Sort the array in reverse order and maintain the index relationship
asort — Sort the array and maintain 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 element in the array
each — Returns the current key/value pair in the array and moves the array pointer one step forward
end — Points the internal pointer of the array to the last element
extract — Import variables from an array into the current symbol table
in_array — Check whether a value exists in the array
key — Get the key name from an associative array
krsort — Sort the array in reverse order by key
ksort — Sort the array by key
list — Assign the values in the array to some variables
natcasesort — Sort the array case-insensitively using the “natural sort” algorithm
natsort — Sort the array using the “natural sort” algorithm
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
sort — Sort an array
uasort — Use a user-defined comparison function to sort the values in an array and maintain index association
uksort — Use a user-defined comparison function to sort the keys in an array Sorting
usort — Use user-defined comparison functions to sort values in an array
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