PHP function to find the length of an array

In PHP programming, an array is a very common data structure that can store a set of values ​​and access its elements through key-value pairs. In the process of operating arrays, we often need to obtain the length of the array (that is, the number of elements in it) to facilitate statistics, operations, and output. So, how to find the length of an array in PHP?

In fact, PHP provides two methods to obtain the length of the array. Below we introduce these two methods in turn.

Method 1: count() function

The count() function is a PHP built-in function, used to get the number of elements in an array. Its basic usage format is:

int count ( mixed $array_or_countable [, int $mode = COUNT_NORMAL ] )

Among them, the $array_or_countable parameter represents the array or countable object to be counted, and the $mode parameter represents the optional counting mode. There will be no detailed explanation here.

For example, we have an array containing 5 elements, the code is as follows:

$fruit = array("apple","banana","orange","watermelon","peach");

We can use the count() function to get the number of elements of the array and output it to the screen Above, the code is as follows:

echo count($fruit); // 输出 5

It should be noted that the count() function counts each array element by default, including nested arrays and empty elements in the array. Therefore, in some cases, the counting results are not as expected.

For example, we have a multi-dimensional array in which one element value is empty. The code is as follows:

$students = array(
  "John" => array("age"=>20,"gender"=>"male"),
  "Alice" => array("age"=>21,"gender"=>"female","major"=>"Math"),
  "Bob" => array()
);

Use the count() function to get the number of elements in the array. The code is as follows:

echo count($students); // 输出 3

As you can see, the number of elements in the array is 3, not the 4 we expected. This is because the count() function also counts nested arrays and counts empty arrays as one element. Therefore, you need to choose to use the count() function according to the actual situation.

Method 2: sizeof() function

In addition to the count() function, PHP also provides another function to obtain the length of the array-the sizeof() function. Its usage is basically the same as the count() function. The code is as follows:

int sizeof ( mixed $array [, int $mode = COUNT_NORMAL ] )

Among them, the $array parameter indicates the array to obtain the array length, and the $mode parameter indicates the optional counting mode, which will not be described here.

For example, we have an array containing 5 elements, the code is as follows:

$fruit = array("apple","banana","orange","watermelon","peach");

We can use the sizeof() function to get the number of elements of the array and output it to the screen Above, the code is as follows:

echo sizeof($fruit); // 输出 5

Similar to the count() function, the sizeof() function will also count empty elements and nested arrays, so you need to pay attention when using it.

It should be noted that the count() function and the sizeof() function return an integer type value, indicating the number of elements in the array. Returns 0 if the array is empty, or 1 if the array is not an array.

The above are two methods of obtaining the array length. Developers can choose the method that suits them according to the actual situation.

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