How to add elements to one-dimensional array in php

The operating environment of this tutorial: windows7 system, PHP8 version, DELL G3 computer

How to add elements to one-dimensional array in php

Method 1. Use the array_unshift() function

The array_unshift() function can insert one or more new elements (key values) at the beginning of the array.

array_unshift($array,$value1,$value2...)

Let’s take a closer look at the following example:

<?php
$arr=array(10,12,20);
array_unshift($arr,8,"9");
var_dump($arr);
?>

array_unshift($arr,8,9)It can be seen that it is inserted at the beginning of the $arr array Two new elements: the numerical value "8" and the string "9", so the output result is:

array_unshift( ) function will not maintain the original numerical index relationship, but will delete all numerical key names and reassign them, that is, count again from 0; but all string key names will remain unchanged.

<?php
header("Content-type:text/html;charset=utf-8");
$arr=array("a"=>"red","b"=>"green",3=>"pink");
echo "原来的数组：";
var_dump($arr);
array_unshift($arr,"blue");
echo "在开头插入一个新元素后：";
var_dump($arr);
?>

Output result:

#Method 2. Use array_splice() function

array_splice() function is A powerful function that can be used to delete array elements, replace array elements, and insert array elements (just set the parameter $length to 0).

array_splice($array,$start,$length,$value)

When $length=0, then the parameter $start can specify the position (subscript) to start inserting, and the parameter $value You can specify the insertion value (if there are multiple values, you need to set it as an array).

The array_splice() function can add elements to the beginning or the end of the array.

• If you want to add elements at the beginning, the value of $start needs to be 0.

<?php
header("Content-type:text/html;charset=utf-8");
$arr1=array(10,12,20);
var_dump($arr1);
array_splice($arr1,0,0,"1");
var_dump($arr1);

$arr2=array(10,12,20);
array_splice($arr2,0,0,array("1",25,"3"));
var_dump($arr2);
?>

• And when the value of $start is set to "array length value ", that is, count($arr) can insert elements at the end of the array.
  

<?php
header("Content-type:text/html;charset=utf-8");
$arr1=array(10,12,20);
array_splice($arr1,count($arr1),0,"1");
var_dump($arr1);

$arr2=array(10,12,20);
array_splice($arr2,count($arr2),0,array("1",25,"3"));
var_dump($arr2);
?>

The output result is:

Method 3. Use the array_push() function to add from the end of the array Element

array_push() function can insert one or more elements (key values) at the end of the array. The syntax is as follows:

array_push($array,$value1,$value2...)

Example:

<?php
$arr=array(10,12,20);
array_push($arr,8,"9",3.14);
var_dump($arr);
?>

It can be seen that 3 elements are inserted at the end of the $arr array: integer "8", string "9" and floating point number "##" #3.14”.

The elements inserted by the array_push() function can be of array type

<?php
$arr=array(10,12,20);
var_dump($arr);
array_push($arr,array(1,2,3));
var_dump($arr);
?>

Method 4. Use the array_pad() function to add elements from the end of the array

array_pad($array,$size,$value)The function can insert a key value $value into the array$array, thereby filling the array to the specified length $size. (The $size parameter can be understood as the final number of elements in the array, that is, the length of the array after the insertion operation).

So how to use the array_pad() function to add elements from the end of the array? The key is the $size parameter.

• When the $size parameter is a positive number, elements are inserted at the end of the array.

<?php
$arr=array(10,12,20);
$result =array_pad($arr,5,1);
var_dump($result);
?>

The elements inserted by the array_pad() function can be of array type, then the original array will become a two-dimensional array.

<?php
header("Content-type:text/html;charset=utf-8");
$arr=array(10,12,20);
$result =array_pad($arr,5,array("张三",25,"男"));
var_dump($result);
?>

The output result is:

Method 5. Use the array_merge() function to add elements from the end of the array

array_merge(array1,array2,array3...) The function is used to merge one or more arrays into one array, and store the values ​​of array2,array3... into array1 in.

If two or more array elements have the same key name, the last element will overwrite the other elements.

<?php
header("Content-type:text/html;charset=utf-8");
$arr=array(10,12,20);
$result =array_merge($arr,array(2,3,4)) ;
var_dump($result);
?>

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