PHP function manual example: array_fill()

PHP is a very popular programming language that is widely used in web development. Among them, functions are one of the important components of PHP. More and more programmers use them to improve the readability, maintainability and reusability of code. In the PHP function library, there is a very useful function called array_fill(). Next, we will introduce its usage and detailed examples in detail.

1. Function introduction

array_fill() function is used to fill an array, that is, fill every element in the array with the same value. This function requires three parameters: starting index, number of elements, and padding value. Next we explain its parameters and return values ​​in detail.

2. Function parameters

array_fill() function has three parameters, their functions are as follows:

(1)start_index: The starting index position to be filled, must is a non-negative integer.

(2)num: The number of elements to be filled must be a non-negative integer.

(3)value: The value to be filled can be of any type.

3. Function return value

array_fill() function returns a new array containing filled elements. If start_index is negative and num is negative, then false is returned, otherwise the value is filled with the starting word and number of elements specified by start_index and num. If num is 0, the function returns an empty array.

4. Function example

Let’s take a look at a simple example to help you better understand the specific usage of the array_fill() function:

<?php
   $array1 = array_fill(0, 5, 10);
   print_r($array1);
?>

输出结果：
Array ( [0] => 10 [1] => 10 [2] => 10 [3] => 10 [4] => 10 )

In this example , we use the array_fill() function to fill a new array. Among them, the value of start_index is 0, which means filling starts from the first position; the value of num is 5, which means filling 5 elements; the value of value is 10, which means filling each element in the array with 10. The final output is an array of 5 elements filled with 10s.

Next let’s look at a slightly more complex example. This example will create a two-dimensional array, filling each element in the first and second levels with a value. The code is as follows:

<?php
  $array2 = array_fill(0, 3, array_fill(0, 3, 1));
  print_r($array2);
?>

输出结果：
 Array ( [0] => Array ( [0] => 1 [1] => 1 [2] => 1 ) 
         [1] => Array ( [0] => 1 [1] => 1 [2] => 1 ) 
         [2] => Array ( [0] => 1 [1] => 1 [2] => 1 ) )

This example is a bit difficult to understand, let’s analyze it carefully. First, the first parameter we pass to the array_fill() function is 0, which means filling starts from the first position of the array. The second parameter is passed an array, please note that the array here is the result of an "array fill" operation: it fills an array of 3 elements and sets the value of each element to 1.

Next, we use the array_fill() function to fill the array. Since the second parameter is set to 3, an array of 3 arrays will be created, filled starting at index 0. But this time instead of passing a value, we pass the result of an array. This array will be filled into the first and second levels of the new array. So the final output result is a 3x3 two-dimensional array filled with 1's.

5. Summary

array_fill() function can help programmers quickly create a new array and fill each of its elements with the same value. In PHP programming, this function is very useful. At the same time, we must also pay more attention to the setting of function parameters and the return value of the function in order to better understand how to use the function.

Finally, we recommend that you practice more function examples to better master their usage and characteristics, thereby improving your programming skills.

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