PHP array learning two-dimensional array calculation array length

In the previous article "PHP Array Learning: A Brief Analysis of Two-Dimensional Array Creation Methods", we introduced how to create two-dimensional arrays (multi-dimensional arrays). If you are interested, you can take a look. Now that we have an array, we need to operate it. Sometimes we need to know the length of the array (the number of all elements in the array). So how to get the array length of a two-dimensional array or even a multi-dimensional array? Today we are here to learn about it with you.

We know how to get the array length of a one-dimensional array. It's very simple. Just use count($arr).

<?php
header("Content-type:text/html;charset=utf-8");
$arr= array("香蕉","苹果","梨子","橙子","橘子","榴莲");
//输出语句
var_dump($arr);
echo "数组长度为：".count($arr);
?>

Output result:

# Is it very simple, what about the two-dimensional array? How to calculate the length of a two-dimensional array or even a multi-dimensional array and count the number of elements?

Two-dimensional arrays are also simple. We still use the count() function. We only need to pass two parameters to the count() function: the first parameter is $array as above, specifying the array to be counted; and the second parameter is $array as above, specifying the array to be counted; The two parameters are $mode, and the value is set to COUNT_RECURSIVE or 1, so that the count() function will recursively calculate the number of elements in the array.

Let’s use two code examples to learn more about how to use the count() function to pass the array length of a multi-dimensional array.

Example 1: The length of the two-dimensional array

<?php
header("Content-type:text/html;charset=utf-8");
$arr= array
("张三",
25,
    array("高数","PHP教程","英语"),
);
//输出语句
echo "数组长度为：".count($arr,1);
?>

Output:

数组长度为：6

Looking at the above output, it is No need to be confused, there are not only 5 elements in the array ("张三"、25、"高书"、"PHP tutorial", "English"), why is the array length displayed in the result not 5, but 6?

In fact, this is because at this time, the count() function loops to count all elements in the two-dimensional array, "array("高num","PHP Tutorial","English")" It will be counted once as a whole, and the elements inside it ("高书", "PHP Tutorial", "English") will be counted again. , so the final result is 6.

We output the $arr array through the var_dump() function and look at its data structure. We can intuitively understand the process of the count() function.

Example 2: Length of three-dimensional array

<?php
header("Content-type:text/html;charset=utf-8");
$arr = array(
        &#39;安徽&#39; => array(
            &#39;合肥&#39;=>array(&#39;蜀山区&#39;,&#39;长丰县&#39;,&#39;肥东&#39;),
			&#39;宿州&#39;=>array(&#39;墉桥区&#39;,&#39;灵璧县&#39;,&#39;泗县&#39;)
        ),
        &#39;河南&#39; => array(
            &#39;洛阳&#39;=>array(&#39;西工区&#39;,&#39;老城区&#39;,&#39;孟津县&#39;),
            &#39;郑州市&#39;=>array(&#39;中原区&#39;,&#39;金水区&#39;)
        )
);
 var_dump($arr);
 echo "数组长度为：".count($arr,1);
?>

Output result:

Extended knowledge:

In addition to using the count() function to calculate the array length, we can also use the sizeof() function. The sizeof() function is an alias of the count() function, and its function and usage are exactly the same as the count() function.

Okay, that’s all. If you want to know anything else, you can click this. → →php video tutorial

Finally, I would like to recommend a free video tutorial on PHP arrays: PHP function array array function video explanation, come and learn!

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