How to query and return the array length in php

How to query and return the length of an array in php: 1. Use the count() function to count the number of all elements in the array, or the number of attributes in the object, with the syntax "count($array)"; 2. Use the sizeof() function, the syntax is "sizeof($array)".

The operating environment of this tutorial: windows7 system, PHP7.1 version, DELL G3 computer

PHP provides us with two functions to calculate The length of the array, respectively, are the count() and sizeof() functions.

Method 1: count() function

count() function can count the number of all elements in the array, or the number of attributes in the object, its syntax format As follows:

count($array [, $mode = COUNT_NORMAL])

The parameter description is as follows:

• $array: is the array or object to be counted;

• $mode : is an optional parameter and can be omitted.

• If the $mode parameter is omitted, or set to COUNT_NORMAL or 0, the count() function will not detect multidimensional arrays;

• If If $mode is set to COUNT_RECURSIVE or 1, the count() function will recursively count the number of elements in the array, which is especially useful for calculating the number of elements in multi-dimensional arrays.

  Possible values ​​for $mode:

  • 0 - Default. Do not count all elements in a multidimensional array

  • 1 - Recursively count the number of elements in an array (count all elements in a multidimensional array)

Tip: If $array is neither an array nor an object, the count() function will return 1; if $array is equal to NULL, the count() function will return 0.

[Example] Use the count() function to count the number of array elements.

<?php
header("Content-type:text/html;charset=utf-8");
$arr = [&#39;苹果&#39;,&#39;香蕉&#39;,&#39;榴莲&#39;,&#39;sizeof()函数&#39;,&#39;数组长度&#39;];
echo &#39;$arr 的长度为：&#39;.count($arr).&#39;<br>&#39;;
$arr2 = [&#39;红色&#39;,&#39;黄色&#39;,[&#39;蓝色&#39;,&#39;sizeof()函数&#39;,&#39;数组长度&#39;]];
echo &#39;$arr2 的长度为：&#39;.count($arr2).&#39;<br>&#39;;
echo &#39;参数 $mode = 1 时，$arr2 的长度为：&#39;.count($arr2, 1).&#39;<br>&#39;;
echo &#39;参数 $mode = 0 时，$arr2 的长度为：&#39;.count($arr2, 0).&#39;<br>&#39;;
?>

The running results are as follows:

$arr 的长度为：5
$arr2 的长度为：3
参数 $mode = 1 时，$arr2 的长度为：6
参数 $mode = 0 时，$arr2 的长度为：3

Note: Line 6 of the code sets $mode to 1, and the count() function will cycle through all elements in the two-dimensional array. At this time['blue','sizeof() function','array length'] will be counted once as a whole, and the elements inside it will be counted again, so the final result is 6.

Method 2: Use sizeof() function

sizeof() function is an alias of count() function, that is, the function and usage of sizeof() function Identical to the count() function.

[Example] Use the sizeof() function to count the number of elements in the array.

<?php
header("Content-type:text/html;charset=utf-8");
$arr = [&#39;苹果&#39;,&#39;香蕉&#39;,&#39;榴莲&#39;,&#39;sizeof()函数&#39;,&#39;数组长度&#39;];
echo &#39;$arr 的长度为：&#39;.sizeof($arr).&#39;<br>&#39;;
$arr2 = [&#39;红色&#39;,&#39;黄色&#39;,[&#39;蓝色&#39;,&#39;sizeof()函数&#39;,&#39;数组长度&#39;]];
echo &#39;$arr2 的长度为：&#39;.sizeof($arr2).&#39;<br>&#39;;
echo &#39;参数 $mode = 1 时，$arr2 的长度为：&#39;.sizeof($arr2, 1).&#39;<br>&#39;;
echo &#39;参数 $mode = 0 时，$arr2 的长度为：&#39;.sizeof($arr2, 0).&#39;<br>&#39;;
?>

The running results are as follows:

$arr 的长度为：5
$arr2 的长度为：3
参数 $mode = 1 时，$arr2 的长度为：6
参数 $mode = 0 时，$arr2 的长度为：3

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