What should I do if the content displayed by php cannot be modified?

PHP is a popular server-side scripting language used by the vast majority of websites to handle dynamic content and interaction with databases. However, sometimes the content displayed in PHP cannot be modified, which brings a lot of trouble to programmers.

There may be many reasons why it cannot be modified. The following are some of the more common situations:

1. The content output by PHP is static
   A very common mistake is that the author Functions such as echo or print_r are used to directly output HTML codes, and these codes are static in nature and cannot be modified. The solution to this problem is to dynamically generate HTML code in PHP and insert it into the web page. Using a template engine like Twig or Smarty in PHP can help avoid this problem.
2. PHP uses caching
   Many PHP frameworks and CMS use caching to speed up website response time. When a website uses caching, the content displayed on the page may not be updated in real time. This means that even if the data changes, the display content of the page will not be updated immediately. The solution to this problem is to clear the cache or turn off caching (which can be controlled in the PHP code), but this may slow down the response speed of the website.
3. PHP data is extracted from the database
   When extracting data from the database, the results may be stored in variables and then displayed on the page through the variables. But if caching is used in the website, these variables may often be cached and lag behind the actual data in the database. The solution to this problem is to use a caching mechanism so that the data can be refreshed immediately after updating.
4. PHP content has been drawn into images
   There are some functions in PHP that can generate and process images. In this case, the image file is generated directly and cached, so it cannot be modified. If the image needs to be changed, a new image needs to be generated.

To sum up, when the data returned by PHP cannot be modified, it may be because the output of the program is static, cached, uses a database cache, or has been converted into an image. . For this type of problem, programmers can choose to adjust the code or configuration according to the specific situation to obtain the expected results. At the same time, using cache will cause problems regardless of the reason, so it is recommended to use this technology only in specific cases to avoid update problems caused by caching.

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