PHP Common Array function usage Summary _php tips

This example describes the usage of PHP's common array functions. Share to everyone for your reference, specific as follows:

1.array Array_merge (Array $array 1 [, Array $array 2 [, $array]])

Function: Merges one or more arrays of cells, and the values in one array are appended to the previous array. Returns an array of results.

If the input array has the same string key name, the value following the key name overrides the previous value. However, if the array contains a numeric key name, the subsequent value will not overwrite the original value, but append to the back.

If only one array is given and the array is a numeric index, the key name is sequentially indexed.

Example 1: The array has the same string key name

$array 1=array (' Color ' => ' greed ', ' 3 ' =>8);
$array 2=array ("A", "Color" => "Red", ' 3 ' =>8);
Var_dump (Array_merge ($array 1, $array 2));

Output:

Array (4) {
  ["Color"]=> string (3) "Red"
  [0]=> Int (8)
  [1]=> string (1) "a"
  [2]=> int (8)
}

The key name repeats the color is overwritten, takes only the later value ' red ', but the numeric key name identical ' 3 ' is not overwritten, but attaches to the back.

2.array array_slice (array $array, int $offset, [, int $length [, bool $preserve _keys]])

function function: Returns a sequence of arrays in an array specified according to the offset and length parameters.

If offset is non-negative: Then the array starts at the offset from the start end. $array =array (1,2,3,4,5,6); Array_slice ($array, 2); equivalent (1,2,3,4,5,6); Red represents the captured array
If offset is negative: the array starts at the offset from the end. Array_slice ($array,-2); equivalent (1,2,3,4,5,6);
If length is positive: the number of intercepts that begin with offset. Array_slice ($array, 2,2); equivalent (1,2,3,4, 5,6);
If length is negative: Then the sequence terminates at such a distance from the end of the array; Array_slice ($array, 2,-1); equivalent (1,2,3,4,5, 6);
The default is: to the end of the array.

On the specific use of array_slice can also refer to the site in the previous "PHP array_slice function usage Examples"

3.array_map (callback $callback, array $arr 1[, array $ ...])

function function: Returns an array that contains the cells of all cells in the ARR1 after the callback action. The number of arguments accepted by callback should be consistent with the number of arrays passed to the Array_map () function.

<?php
function Cube ($n)
{return
  ($n * $n * $n);
}
$a = Array (1, 2, 3, 4, 5);
$b = Array_map ("cube", $a);
Print_r ($b);
? >

Output:

Array
(
  [0] => 1
  [1] => 8
  [2] =>
  [3] =>
  [4] =>
)

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