Summary of examples of commonly used array functions in PHP

The examples in this article summarize the commonly used array functions in PHP. Share it with everyone for your reference, as follows:

1. array array_merge(array $array1 [, array $array2 [, $array]])

Function function: Merge one or more The elements of the arrays are combined, 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 after the key name will overwrite the previous value. However, if the array contains numeric keys, the subsequent values ​​will not overwrite the original values ​​but will be appended to them.

If only an array is given and the array is numerically indexed, the key names are re-indexed in a consecutive manner.

Example 1: There are the same string key names in the array

$array1=array('color'=>'greed','3'=>8);
$array2=array("a",'color'=>"red",'3'=>8);
var_dump(array_merge($array1,$array2));

Output:

array（4）{
  ["color"]=> string(3) "red"
  [0]=> int(8)
  [1]=> string(1) "a"
  [2]=> int(8)
}

The color with repeated key names is overwritten, and only the subsequent value 'red' is taken, while the '3' with the same numerical key name is not overwritten, but appended to the end.

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

Function function: Return the value specified by the offset and length parameters A sequence in the array array.

If offset is non-negative: the array will start from the offset from the beginning to offset. $array=array(1,2,3,4,5,6); array_slice($array,2); equivalent to (1,2,3,4,5,6); red represents the intercepted array

If offset is negative: the array will start at the offset from the end to offset. array_slice($array,-2); Equivalent to (1,2,3,4,5,6);

If length is positive: the number of interceptions starting from offset. array_slice($array,2,2); Equivalent to (1,2,3,4,5,6);

If length is negative: the sequence will terminate this far from the end of the array; array_slice($array,2,-1); Equivalent to (1,2,3,4,5,6);
The default is: to the end of the array.

3. array_map(callback $callback, array $arr1[, array $.....])

Function function: Return an array that contains all units in arr1 The unit after callback function. The number of arguments accepted by callback should match 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] => 27
  [3] => 64
  [4] => 125
)

I hope this article will be helpful to everyone in PHP programming.

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