The proficiency of arrays can sometimes solve many problems. Familiarity with the relevant functions can do more with less. Look at the following functions about arrays are you familiar with it?
Basic functions of array manipulation
The key name and value of the array
- Array_values ($arr); Get the value of an array
- Array_keys ($arr); Gets the key name of the array
- Array_flip ($arr); the values in the array are exchanged with the key names (if there are duplicates, the previous one will be overwritten by the following)
- In_array ("Apple", $arr); Retrieve 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 ($arr); Returns the cell in the array
- POS ($arr); Returns the current cell in the array
- Key ($arr); Returns the key name of the current cell in the array
- Prev ($arr); Rewind the internal pointer in the array back to a
- Next ($arr); Move the inner pointer in the array forward one
- End ($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 the elements in an array into variables 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, 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"), pressing 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, $arr 2); You can work with multiple arrays (they should be the same length when using two or more arrays)
- Array_filter ($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 ($arr, "function", "*"), converted to a single-valued function (* The first value of an array)
Vi. Ordering of arrays
Sort by array of element values
- Sort ($arr), sorted by order of small to large (the second argument is sorted by what sort), and the array ordering of the key names is ignored
- Rsort ($arr); Sort by order of large to small (the second argument is sorted by what sort) ignores the array ordering of the key names
- Usort ($arr, "function"); Sorts the values in the array using a user-defined comparison function (two parameters in function, 0 for equality, positive for the first one greater than the second, negative for the first less than the second) to sort the array with the key name omitted
- Asort ($arr); Sort by the order of small to large (the second argument is sorted by what way) the array of reserved key names
- Arsort ($arr); Sort by order of large to small (the second parameter is sorted by what sort) the array of reserved key names
- Uasort ($arr, "function"); Sorts the values in the array using a user-defined comparison function (two parameters in function, 0 for equality, positive for the first one greater than the second, negative for the first one less than the second) to sort the array of reserved key names
Sort arrays by key names
- Ksort ($arr); Order by Key Name
- Krsort ($arr); reverse order by Key name
- Uksort ($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 one less than the second one)
Sort by natural sort
- Natsort ($arr); natural sort (Ignore key name)
- Natcasesort ($arr); natural sort (ignoring case, ignoring 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); merges 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+ $arr 2; For the same key name only the latter
- Array_merge_recursive ($arr 1, $arr 2); recursive merge operations, if the array has the same string key name, the values will be merged into an array. If a value is itself an array, it will be merged into another array according to the corresponding key name. When the array has the same array key name, the latter value will not overwrite the original value, but append to the back
The difference set of an array
- Array_diff ($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, $arr 2); Returns an array of intersection results, and the key names are also compared
Eight, other array functions
Sum of array elements
- Range (0,12); Create an array containing the specified range of cells
- Array_unique ($arr); Removes duplicate values from the array, preserving the original key names in the new arrays
- Array_reverse ($arr, TRUE); Returns an array whose cell order is the opposite of the original array, if the second argument is TRUE to preserve the original key name
- Srand (float) microtime () *10000000); Random seed Trigger
- Array_rand ($arr, 2); Randomly remove one or more elements from an array
- Shuffle ($arr); disturb the order of the array
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