PHP uses the array_slice function to obtain a random array or the first few pieces of data, how many array_slice pieces_PHP tutorial

php uses the array_slice function to get a random array or the first few pieces of data, array_slice several pieces

Let me tell you the basic syntax first:

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

array_slice() returns a sequence in the array specified by the offset and length parameters.

If offset is non-negative, the sequence will start at this offset in array. If offset is negative, the sequence will start this far from the end in the array.

If length is given and positive, there will be this many cells in the sequence. If length is given and negative, the sequence will terminate this far from the end of the array. If omitted, the sequence will start at offset and go to the end of array.

Note that array_slice() will reset the keys of the array by default. As of PHP 5.0.2, this behavior can be changed by setting preserve_keys to TRUE.

$input = array("a", "b", "c", "d", "e");
$output = array_slice($input, );  //返回下标开始的数组 returns "c", "d", and "e"
$output = array_slice($input, -, ); // returns "d"
$output = array_slice($input, , ); // returns "a", "b", and "c"
// note the differences in the array keys
print_r(array_slice($input, , -));
print_r(array_slice($input, , -, true));

If you need to return a few random pieces of data, you can first use shuffle($input); to scramble the original array, and then use array_slice to obtain it

PS: PHP array_slice() function

Definition and usage

The array_slice() function removes a segment of value from the array based on conditions and returns it.

Note: If the array has string keys, the returned array will retain the key names. (see example 4)

Grammar

Copy code The code is as follows:
array_slice(array,offset,length,preserve)

例子 1

<&#63;php
$a=array(0=>"Dog",1=>"Cat",2=>"Horse",3=>"Bird");
print_r(array_slice($a,1,2));
&#63;>

输出：

复制代码 代码如下:
Array ( [0] => Cat [1] => Horse )

例子 2

带有负的 offset 参数：

<&#63;php
$a=array(0=>"Dog",1=>"Cat",2=>"Horse",3=>"Bird");
print_r(array_slice($a,-2,1));
&#63;>

输出：

复制代码 代码如下:
Array ( [0] => Horse )

例子 3

preserve 参数设置为 true：

<&#63;php
$a=array(0=>"Dog",1=>"Cat",2=>"Horse",3=>"Bird");
print_r(array_slice($a,1,2,true));
&#63;>

输出：

复制代码 代码如下:
Array ( [1] => Cat [2] => Horse )

例子 4

带有字符串键：

<&#63;php
$a=array("a"=>"Dog","b"=>"Cat","c"=>"Horse","d"=>"Bird");
print_r(array_slice($a,1,2));
&#63;>

输出：

复制代码 代码如下:
Array ( [b] => Cat [c] => Horse )

以上就是本文给大家介绍的php 利用array_slice函数获取数组随机或前几条数据，希望大家喜欢。