Home Backend Development PHP Tutorial Detailed explanation and example code of using PHP foreach loop_PHP tutorial

Detailed explanation and example code of using PHP foreach loop_PHP tutorial

Jul 21, 2016 pm 03:38 PM
array foreach php and code use Basic Example cycle Detailed explanation grammar

The basic syntax of foreach is as follows:
FOREACH ($array_variable as $value)
{
[code to execute]
}
or
FOREACH ($array_variable as $key => $value)
{
[code to execute]
}
In both cases, multiple [code to execute] will be executed that is equal to the array element in $array_variable number.
Let’s look at an example. Suppose we have the following code snippet:

Copy code The code is as follows:

$array1 = array(1,2,3 ,4,5);
FOREACH ($array1 as $abc)
{
print "new value is " . $abc*10 . "
";
}

Output result
new value is 10
new value is 20
new value is 30
new value is 40
new value is 50
foreach loop above experience All 5 elements of the array $array1 are printed out each time in a statement containing 10 times the value of the array element.
The function of foreach is to iterate through all the values ​​​​of the current array and assign them to $var
Official example code:
Copy code The code is as follows :

/* foreach example 1: value only */
$a = array(1, 2, 3, 17);
foreach ($ a as $v) {
echo "Current value of $a: $v.n";
}
/* foreach example 2: value (with key printed for illustration) */
$a = array(1, 2, 3, 17);
$i = 0; /* for illustrative purposes only */
foreach ($a as $v) {
echo "$a[$i] => $v.n";
$i++;
}
/* foreach example 3: key and value */
$a = array(
"one" => 1,
"two" => 2,
"three" => 3,
"seventeen" => 17
);
foreach ($a as $k => $v) {
echo "$a[$k] => $v.n";
}
/* foreach example 4: multi-dimensional arrays */
$a = array() ;
$a[0][0] = "a";
$a[0][1] = "b";
$a[1][0] = "y";
$a[1][1] = "z";
foreach ($a as $v1) {
foreach ($v1 as $v2) {
echo "$v2n";
}
}
/* foreach example 5: dynamic arrays */
foreach (array(1, 2, 3, 4, 5) as $v) {
echo "$vn";
}
?>

Let’s look at an example of foreach operating on multidimensional data
Copy the code The code is as follows :

$s = array(array(1,2),array(3,4),array(5,6));
foreach( $s as $v => $_v )
{
foreach( $_v as $vc => $_vc )
{
echo $_vc[0],'|'.$_vc[1],'< br /> >
Copy code

The code is as follows:

foreach ($array as $key=>$value)
{
…… } For ease of understanding, we assume that $array here is a one-dimensional related array, $key is the index of the array, $value is the value of this index, and their names can be arbitrary. They are called $key and $value for ease of understanding. In order to allow you to better understand the working process of foreach, let's create an array:
$array = array('first'=>'ibm','second'=>'hp');
Now we simulate the PHP service to use foreach to traverse $array:



Copy code
The code is as follows:


foreach ($array as $key=>$value)
{
echo $key.'=>'.$value; }
The first loop, $key = 'first', $value = 'ibm', at this time, foreach actually performs an invisible operation on $array: next($array), moving the array pointer forward (The "forward" here is the same as in the PHP manual, not what we usually understand as "forward") Move one. Then the echo statement outputs "first=>ibm".
In the second loop, it will first determine whether the current pointer of the array $array has reached the end of the array. If so, end the loop, otherwise it will enter the second loop. Of course, such a judgment will also occur when entering the first loop. If $array is an empty array, then the statements below the loop will be executed directly. At this time, $key = 'second', 'value' = 'hp', and after next($array), "second=>hp" is output. Then it is judged that the array pointer has reached the end and the following statement is executed.
By now you should have some understanding of the foreach loop, right? Another thing to note is that foreach only passes a value each time, rather than actually operating on the array elements. Specific to the above example, if you want to add the string 'company' after each array element, then the operation $value .= 'company' will not work. It will not change the value of the array element. At this time you should use it like this: $array[$key] .= 'company';

For more information, please refer to: php foreach
php foreach, while performance comparison
php loop

www.bkjia.comtruehttp: //www.bkjia.com/PHPjc/321830.htmlTechArticleThe basic syntax of foreach is as follows: FOREACH ($array_variable as $value) { [code to execute] } or FOREACH ($ array_variable as $key = $value) { [code to execute] } In both cases, more...
Statement of this Website
The content of this article is voluntarily contributed by netizens, and the copyright belongs to the original author. This site does not assume corresponding legal responsibility. If you find any content suspected of plagiarism or infringement, please contact admin@php.cn

Hot AI Tools

Undresser.AI Undress

Undresser.AI Undress

AI-powered app for creating realistic nude photos

AI Clothes Remover

AI Clothes Remover

Online AI tool for removing clothes from photos.

Undress AI Tool

Undress AI Tool

Undress images for free

Clothoff.io

Clothoff.io

AI clothes remover

Video Face Swap

Video Face Swap

Swap faces in any video effortlessly with our completely free AI face swap tool!

Hot Tools

Notepad++7.3.1

Notepad++7.3.1

Easy-to-use and free code editor

SublimeText3 Chinese version

SublimeText3 Chinese version

Chinese version, very easy to use

Zend Studio 13.0.1

Zend Studio 13.0.1

Powerful PHP integrated development environment

Dreamweaver CS6

Dreamweaver CS6

Visual web development tools

SublimeText3 Mac version

SublimeText3 Mac version

God-level code editing software (SublimeText3)

PHP 8.4 Installation and Upgrade guide for Ubuntu and Debian PHP 8.4 Installation and Upgrade guide for Ubuntu and Debian Dec 24, 2024 pm 04:42 PM

PHP 8.4 brings several new features, security improvements, and performance improvements with healthy amounts of feature deprecations and removals. This guide explains how to install PHP 8.4 or upgrade to PHP 8.4 on Ubuntu, Debian, or their derivati

7 PHP Functions I Regret I Didn't Know Before 7 PHP Functions I Regret I Didn't Know Before Nov 13, 2024 am 09:42 AM

If you are an experienced PHP developer, you might have the feeling that you’ve been there and done that already.You have developed a significant number of applications, debugged millions of lines of code, and tweaked a bunch of scripts to achieve op

How To Set Up Visual Studio Code (VS Code) for PHP Development How To Set Up Visual Studio Code (VS Code) for PHP Development Dec 20, 2024 am 11:31 AM

Visual Studio Code, also known as VS Code, is a free source code editor — or integrated development environment (IDE) — available for all major operating systems. With a large collection of extensions for many programming languages, VS Code can be c

Explain JSON Web Tokens (JWT) and their use case in PHP APIs. Explain JSON Web Tokens (JWT) and their use case in PHP APIs. Apr 05, 2025 am 12:04 AM

JWT is an open standard based on JSON, used to securely transmit information between parties, mainly for identity authentication and information exchange. 1. JWT consists of three parts: Header, Payload and Signature. 2. The working principle of JWT includes three steps: generating JWT, verifying JWT and parsing Payload. 3. When using JWT for authentication in PHP, JWT can be generated and verified, and user role and permission information can be included in advanced usage. 4. Common errors include signature verification failure, token expiration, and payload oversized. Debugging skills include using debugging tools and logging. 5. Performance optimization and best practices include using appropriate signature algorithms, setting validity periods reasonably,

How do you parse and process HTML/XML in PHP? How do you parse and process HTML/XML in PHP? Feb 07, 2025 am 11:57 AM

This tutorial demonstrates how to efficiently process XML documents using PHP. XML (eXtensible Markup Language) is a versatile text-based markup language designed for both human readability and machine parsing. It's commonly used for data storage an

PHP Program to Count Vowels in a String PHP Program to Count Vowels in a String Feb 07, 2025 pm 12:12 PM

A string is a sequence of characters, including letters, numbers, and symbols. This tutorial will learn how to calculate the number of vowels in a given string in PHP using different methods. The vowels in English are a, e, i, o, u, and they can be uppercase or lowercase. What is a vowel? Vowels are alphabetic characters that represent a specific pronunciation. There are five vowels in English, including uppercase and lowercase: a, e, i, o, u Example 1 Input: String = "Tutorialspoint" Output: 6 explain The vowels in the string "Tutorialspoint" are u, o, i, a, o, i. There are 6 yuan in total

Explain late static binding in PHP (static::). Explain late static binding in PHP (static::). Apr 03, 2025 am 12:04 AM

Static binding (static::) implements late static binding (LSB) in PHP, allowing calling classes to be referenced in static contexts rather than defining classes. 1) The parsing process is performed at runtime, 2) Look up the call class in the inheritance relationship, 3) It may bring performance overhead.

What are PHP magic methods (__construct, __destruct, __call, __get, __set, etc.) and provide use cases? What are PHP magic methods (__construct, __destruct, __call, __get, __set, etc.) and provide use cases? Apr 03, 2025 am 12:03 AM

What are the magic methods of PHP? PHP's magic methods include: 1.\_\_construct, used to initialize objects; 2.\_\_destruct, used to clean up resources; 3.\_\_call, handle non-existent method calls; 4.\_\_get, implement dynamic attribute access; 5.\_\_set, implement dynamic attribute settings. These methods are automatically called in certain situations, improving code flexibility and efficiency.

See all articles