How to fill the array if there are not enough array elements in php

Two methods for PHP to fill an array: 1. Fill the array to the specified length with the specified value through array_pad(), the syntax is "array_pad(original array, length, specified value)". 2. Fill the array to the specified length with the specified value through array_fill(), the syntax is "array_fill (start filling position, filling length, specified value)".

The operating environment of this tutorial: windows7 system, PHP version 8.1, DELL G3 computer

PHP provides 2 types of fill arrays Function to a specified length:

• array_pad(): Fills an array with a given value

• array_fill(): To fill Create a new array using the data method

1. Use array_pad() to fill the array

array_pad() function can fill the array with a certain value to the specified length, the syntax is as follows:

array array_pad ( array $arr, int $size , mixed $value )

Parameter description:

• arr represents the array to be filled.
• size represents the length to be filled:
  • If size is a positive number, fill to the right side of the array;
  • If size is a negative number, start from the left Filling;
  • If the absolute value of size is less than or equal to the length of the arr array, there will be no filling.
• value represents the value to be filled.

array_pad() function will fill the array arr to the length size with the value value.

Return value: Return the filled array. The returned array is just a copy, the original array will not be changed.

Usage examples are as follows:

<?php
header(&#39;content-type:text/html;charset=utf-8&#39;);  
$arr = array(12, 10, 9);
$result = array_pad($arr, 5, 0);  //从数组右侧开始, 用0填补数组到含有5个元素
var_dump($result);
$result = array_pad($arr, -7, -1);  //从数组左侧开始, 用-1填补数组到含有7个元素
var_dump($result);
$result = array_pad($arr, 2, "noop");  // 第二个参数小于数组长度, 不填补
var_dump($result);
?>

2. Use array_fill() to fill the array

array_fill() function A new array will be created by filling data, or a certain value will be used to fill the array to the specified length. The syntax is as follows:

array array_fill ( int $start_index , int $num , mixed $value )

Parameter description:

• start_index means Array index, that is, where to start filling the array:
  • If start_index is a non-negative number, the index of the array will start from start_index and end with start_index num - 1;
  • If start_index is a negative number, the array The index of will consist of start_index, 0, 1, 2, ..., num-1.
• num represents the length to be filled.
• value represents the value to be filled.

array_fill() will create a new array containing num elements, where the value of each element is value. Unlike array_pad(), array_fill() creates a new array by filling it, rather than based on the original array.

Return value: Return the new array after filling.

Usage examples are as follows:

<?php
header(&#39;content-type:text/html;charset=utf-8&#39;);  
$a = array_fill(5, 6, &#39;banana&#39;);  //使用banana填充数组到6个元素, 索引键由数字5开始
$b = array_fill(-2, 4, &#39;pear&#39;);  //使用pear填充数组到4个元素, 索引键由-2开始
$c = array_fill(3, 2, array(1,2,3));  // 用一个数组填充成一个二维数组
var_dump($a);
var_dump($b);
var_dump($c);
?>

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