What should I do if I get an error in php setcookie?
php setcookie reports an error because setcookie() has output before. The solution is to send the output echo data and the cookie in the header together.
The operating environment of this article: windows7 system, PHP7.1 version, DELL G3 computer
What should I do if php setcookie reports an error?
There cannot be any output before PHP setcookie()
PHP’s setcookie function, the manual says this:
setcookie() defines a cookie to be sent along with the rest of the HTTP headers. Like other headers, cookies must be sent before any output from your script (this is a protocol restriction). This requires that you place calls to this function prior to any output, including <html> and <head> tags as well as any whitespace.
The general meaning is Nothing can be output to the client browser before setcookie, otherwise an error will be reported. However, after testing, it was found that no error was reported. Continue to read the manual:
You can use output buffering to send output prior to the call of this function, with the overhead of all of your output to the browser being buffered in the server until you send it. You can do this by calling ob_start() and ob_end_flush() in your script, or setting the output_buffering configuration directive on in your php.ini or server configuration files.
So I modified the output_buffering of php.ini (PHP version 5.4) to 0, which means turning off the buffer. (It is closed below PHP 5.3, and is enabled by default after 5.3, with a value of 4096)
means that if ob_start and ob_end_flush are set to output the buffer before outputting the cookie, no error will be reported. So, why is there no error when the cookie and buffer data are returned together? It should be because: the data in the buffer will be organized into a complete HTTP packet and sent out.
We can take a look at the error message:
echo "i am going to setcookie"; var_dump(setcookie('buhehe', 'asdasdasdasdad')); print_r($_COOKIE);
"Please do not modify the header information because the header has already been sent." Obviously, buffering is not used area output, the header will be returned to the browser first, and then when setcookie is used to send the header information, an error will be reported - it does not comply with the specifications of the HTTP protocol. Because the HTTP protocol stipulates that the header should be output before the body.
I modified the code and sent the output echo data and the cookie in the header together.
ob_start(); echo "i am going to setcookie"; var_dump(setcookie('buhehe', 'asdasdasdasdad')); ob_end_flush(); print_r($_COOKIE);
The results are as follows:
When you set output_buffering to 0, that is, when you turn off the buffer in php.ini, you need to manually ob_start to turn on the buffer. District.
Why do some developers, when testing, find that there is no error after echoing the information before setcookie?
Because most of the current PHP applications are 5.3, and some even use 7. In the PHP5.3 version, because the buffer is enabled by default and the default size is 4096, the echo data before setcookie and the cookie header information will be encapsulated into an HTTP packet in the buffer and sent to the client~ Therefore, the error message in the picture above will not be generated (please do not modify the HTTP header information)~~
Recommended learning: "PHP Video Tutorial"
The above is the detailed content of What should I do if I get an error in php setcookie?. For more information, please follow other related articles on the PHP Chinese website!
Hot AI Tools
Undresser.AI Undress
AI-powered app for creating realistic nude photos
AI Clothes Remover
Online AI tool for removing clothes from photos.
Undress AI Tool
Undress images for free
Clothoff.io
AI clothes remover
Video Face Swap
Swap faces in any video effortlessly with our completely free AI face swap tool!
Hot Article
Hot Tools
Notepad++7.3.1
Easy-to-use and free code editor
SublimeText3 Chinese version
Chinese version, very easy to use
Zend Studio 13.0.1
Powerful PHP integrated development environment
Dreamweaver CS6
Visual web development tools
SublimeText3 Mac version
God-level code editing software (SublimeText3)
Hot Topics
1386
52
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
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
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 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
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,
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::).
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?
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.
