Require vs. Include in PHP: What's the Difference and When Should I Use Each?

Understanding the Differences: require vs. include, require_once vs. require

In PHP, developers often encounter the need to include external files into their code. While both require and include allow you to accomplish this task, their handling of errors differs significantly.

require vs. include

The primary distinction between require and include lies in their error handling. When include encounters an error or cannot find the specified file, it generates a warning but allows the script to continue executing. On the other hand, require considers such issues fatal errors and halts the execution of the script.

require_once vs. include_once

Similar to their counterparts, require_once and include_once offer a slightly different functionality. Both these statements check if the specified file has already been included before proceeding. If it has, they prevent multiple inclusions, ensuring that duplicate code is not executed.

Why Use *_once Variants?

Although *_once variants were considered useful in older versions of PHP, their significance has diminished in modern development practices. Their usage often suggests code structuring issues or thoughtless adherence to outdated habits.

Conclusion

When choosing between require and include, consider the desired error handling behavior. For fatal errors, use require; for warnings, use include. In most scenarios, avoiding *_once variants eliminates potential code redundancy and promotes code clarity.

The above is the detailed content of Require vs. Include in PHP: What's the Difference and When Should I Use Each?. For more information, please follow other related articles on the PHP Chinese website!