How to add an array in php

PHP is a very popular programming language. One of its advantages is its convenient array operation function. In PHP, we can easily define, print and manipulate arrays, however, adding arrays in practice also requires some skills and knowledge. This article will introduce different methods and techniques for adding arrays in PHP.

1. Basic array addition method

In PHP, you can use the following method to add an array:

1. Directly define the array

The most basic way to define an array is to define it directly in the code. When defining an array, use the array variable name and then enter the array elements through square brackets. For example:

$myArray = array('apple', 'banana', 'orange');

This code snippet creates a variable named myArray that contains three string-type values: "apple", "banana", and "orange".

2. Use array notation [ ] Add elements directly

You can also use square brackets to add new elements to an array. To do this, you just need to provide the index of the element and assign the value to it. For example:

$myArray = array('apple', 'banana', 'orange');
$myArray[] = 'grape';

The second line of code inserts a new element "grape" to the end of the $myArray array. This defines an array containing 4 elements.

3. Add elements using associative arrays

In PHP, in addition to ordinary arrays, there are also associative arrays. This kind of array uses strings as indexes instead of numbers. As follows:

$myArray = array(
    'apple' => 1.5,
    'banana' => 2.0,
    'orange' => 1.2
);

The indexes here are 'apple', 'banana' and 'orange', and each index corresponds to their corresponding values ​​1.5, 2.0 and 1.2. Adding elements to this array requires the same method. For example, if you want to add a yellow apple to this array and specify the price as 1.8, you can do this:

$myArray['yellow apple'] = 1.8;

This statement adds a new element 'yellow apple' to $myArray, and assigned its value to be 1.8.

2. Other methods of adding array elements

In addition to the above methods, PHP also provides some other methods for adding elements to an array:

1. Use array_push() Function

array_push() The function adds one or more elements to the end of the array. For example:

$myArray = array('apple', 'banana', 'orange');
array_push($myArray, 'grape', 'pineapple');

This code adds a new element 'grape' and 'pineapple' to the $myArray array.

2. Use the array_unshift() function

array_unshift() function to add one or more elements to the head of the array. For example:

$myArray = array('apple', 'banana', 'orange');
array_unshift($myArray, 'grape', 'pineapple');

This code adds a new element 'grape' and 'pineapple' to the $myArray array.

3. Using the array_merge() function

array_merge() The function allows merging two arrays into one array. For example:

$myArray1 = array('apple', 'banana', 'orange');
$myArray2 = array('grape', 'pineapple');

$myArray3 = array_merge($myArray1, $myArray2);

This code snippet defines $myArray3, which is the combined result of $myArray1 and $myArray2. When adding an element to a new array, we first add the element to the old array and then merge the two into the new array using the array_merge() function.

3. How to check whether the array is empty

Before adding data to the array, we usually need to check whether the array is empty. PHP provides several functions to achieve this function, such as empty(), isset(), count(). The following is a brief introduction to these functions:

1. empty()

##empty() The function is used to check whether a variable Is empty. If the variable does not exist, the value is null, an empty string, or 0, the variable is accepted as empty. If the array $myArray is empty, use the following code:

if(empty($myArray)) {
    echo 'array is empty';
}

2. isset()

##isset()

Function Used to check whether the variable has been defined and initialized. If the variable $myArray has been initialized, you can use the following code to check whether $myArray is empty: <pre class="brush:php;toolbar:false">if(isset($myArray) &amp;&amp; !empty($myArray)) {     echo 'array is not empty'; }</pre>The

isset()

function in this code ensures that the variable has been initialized. If the variable is undefined, isset() returns false.

count()

count()

The function can get the number of elements of the array. For example: <pre class="brush:php;toolbar:false">$count = count($myArray); if ($count == 0) {     echo 'array is empty'; }</pre>First, we get the number of elements of the array $myArray through the

count()

function. Then, in an if statement, we check if it is equal to zero. If equal to zero, the array is empty. Summary

Php provides many reliable methods for adding elements to an array. We can use basic definitions, add elements through square brackets, use associative arrays, use the

array_push()

and array_unshift() functions, use the array_merge() function and other methods to add elements. Before writing any code, we should always check if the array is empty. We can do this using functions such as empty(), isset(), count(), etc. Knowing how to add and inspect arrays is an important foundation for PHP. These methods and techniques allow us to process and maintain variables more efficiently.

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