search
HomeBackend DevelopmentPHP TutorialPHP Task Learning 1: Using Variables in Web Pages_PHP Tutorial

PHP Task Learning 1: Using Variables in Web Pages_PHP Tutorial

Jul 21, 2016 pm 02:54 PM
phponeTaskuseMemoryVarietyvariableCanexiststudydefinitionoftypeWeb page

⚑Definition of variables

⚑Type of variables

⚑Use of variables

Variables can exist in memory. Objects are constantly changing. We can imagine the memory as a street. There are many residents in the street. Each resident will have his own house number. This is like an address in the memory (a concept often mentioned in the C language). , we won’t discuss it much here), for one of the residents we can say it is Building 1, No. 1, or it can be said to be Wang Xiaoming’s home, using a name to replace an address. The number of people in Wang Xiaoming's family at a given time is a variable quantity. There may be 3 people at noon, only 1 person in the afternoon, and 5 people at night. Therefore, if we want to refer to a certain address in the memory, we can also call it A, or area. This is the variable.

Let’s demonstrate the declaration of variables in PHP.

Use "$" to add a variable name, such as $a, $var_name.

Note three points when declaring variables in PHP:

1. Variable names can only consist of English letters (A-Z, a-z), numbers (0-9) and underscores.

2. Variable names in PHP are case-sensitive, that is, $VAR_NAME and $var_name are two different variables.

3. A variable declaration or assignment must end with a semicolon (;).

The type definition of variables in PHP is very simple. Generally, there is no need to use keyword declarations, and it can be reflected in the form of assignment.

For example, declare an integer variable

$x=100;

Declare a character variable

$str="Iam a Chinese!" ;

Declare a Boolean variable

$bool=true;

Use variables in web pages.

For example, we want to display a sentence on the web page, "I am a Chinese", "I am 28 years old this year".

Copy to ClipboardLiehuo.Net CodesQuoted content: [www.bkjia.com] $str="I am a Chinese";
$age=28;
echo$str."
";
echo"I am this year".$ age."Age";
?>

Line 1 "
Line 2 $str="I am a Chinese"; defines a string variable str, whose value is "I am a Chinese".

Line 3 $age=28; defines an integer variable age and assigns it a value of 28.

Line 4 echo$str."
";, echo is the keyword used for output in PHP, and the content following it indicates that it is the content that needs to be output, that is, $str is the need Output variables, and the . after $str is a mark used to connect multiple variables or variables with general content. Here, a newline symbol
will be displayed after $str.

Line 5 echo "I am this year".$age."years old";, this sentence is understood in the same way as line 4. The sentence "I am 28 years old this year" is divided into three parts. "I am this year" is the first part. 28 is replaced by the variable $age. "Age" is the third part. They are connected by .

Line 6 "?>" indicates the end of this PHP file.

At this point, mission 1 is over. Up to now, you can express what you want to say on the web page in the form of PHP.

Author’s blog: http://walkbro.cnblogs.com/

www.bkjia.comtruehttp: //www.bkjia.com/PHPjc/364495.htmlTechArticleDefinition of variables Type of variables Usage of variables Variables are objects that exist in memory and can constantly change. We can imagine memory as a street with many residents...
Statement
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
What are some common problems that can cause PHP sessions to fail?What are some common problems that can cause PHP sessions to fail?Apr 25, 2025 am 12:16 AM

Reasons for PHPSession failure include configuration errors, cookie issues, and session expiration. 1. Configuration error: Check and set the correct session.save_path. 2.Cookie problem: Make sure the cookie is set correctly. 3.Session expires: Adjust session.gc_maxlifetime value to extend session time.

How do you debug session-related issues in PHP?How do you debug session-related issues in PHP?Apr 25, 2025 am 12:12 AM

Methods to debug session problems in PHP include: 1. Check whether the session is started correctly; 2. Verify the delivery of the session ID; 3. Check the storage and reading of session data; 4. Check the server configuration. By outputting session ID and data, viewing session file content, etc., you can effectively diagnose and solve session-related problems.

What happens if session_start() is called multiple times?What happens if session_start() is called multiple times?Apr 25, 2025 am 12:06 AM

Multiple calls to session_start() will result in warning messages and possible data overwrites. 1) PHP will issue a warning, prompting that the session has been started. 2) It may cause unexpected overwriting of session data. 3) Use session_status() to check the session status to avoid repeated calls.

How do you configure the session lifetime in PHP?How do you configure the session lifetime in PHP?Apr 25, 2025 am 12:05 AM

Configuring the session lifecycle in PHP can be achieved by setting session.gc_maxlifetime and session.cookie_lifetime. 1) session.gc_maxlifetime controls the survival time of server-side session data, 2) session.cookie_lifetime controls the life cycle of client cookies. When set to 0, the cookie expires when the browser is closed.

What are the advantages of using a database to store sessions?What are the advantages of using a database to store sessions?Apr 24, 2025 am 12:16 AM

The main advantages of using database storage sessions include persistence, scalability, and security. 1. Persistence: Even if the server restarts, the session data can remain unchanged. 2. Scalability: Applicable to distributed systems, ensuring that session data is synchronized between multiple servers. 3. Security: The database provides encrypted storage to protect sensitive information.

How do you implement custom session handling in PHP?How do you implement custom session handling in PHP?Apr 24, 2025 am 12:16 AM

Implementing custom session processing in PHP can be done by implementing the SessionHandlerInterface interface. The specific steps include: 1) Creating a class that implements SessionHandlerInterface, such as CustomSessionHandler; 2) Rewriting methods in the interface (such as open, close, read, write, destroy, gc) to define the life cycle and storage method of session data; 3) Register a custom session processor in a PHP script and start the session. This allows data to be stored in media such as MySQL and Redis to improve performance, security and scalability.

What is a session ID?What is a session ID?Apr 24, 2025 am 12:13 AM

SessionID is a mechanism used in web applications to track user session status. 1. It is a randomly generated string used to maintain user's identity information during multiple interactions between the user and the server. 2. The server generates and sends it to the client through cookies or URL parameters to help identify and associate these requests in multiple requests of the user. 3. Generation usually uses random algorithms to ensure uniqueness and unpredictability. 4. In actual development, in-memory databases such as Redis can be used to store session data to improve performance and security.

How do you handle sessions in a stateless environment (e.g., API)?How do you handle sessions in a stateless environment (e.g., API)?Apr 24, 2025 am 12:12 AM

Managing sessions in stateless environments such as APIs can be achieved by using JWT or cookies. 1. JWT is suitable for statelessness and scalability, but it is large in size when it comes to big data. 2.Cookies are more traditional and easy to implement, but they need to be configured with caution to ensure security.

See all articles

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

PhpStorm Mac version

PhpStorm Mac version

The latest (2018.2.1) professional PHP integrated development tool

Atom editor mac version download

Atom editor mac version download

The most popular open source editor

WebStorm Mac version

WebStorm Mac version

Useful JavaScript development tools

SecLists

SecLists

SecLists is the ultimate security tester's companion. It is a collection of various types of lists that are frequently used during security assessments, all in one place. SecLists helps make security testing more efficient and productive by conveniently providing all the lists a security tester might need. List types include usernames, passwords, URLs, fuzzing payloads, sensitive data patterns, web shells, and more. The tester can simply pull this repository onto a new test machine and he will have access to every type of list he needs.

EditPlus Chinese cracked version

EditPlus Chinese cracked version

Small size, syntax highlighting, does not support code prompt function