Require vs. Include vs. Require_Once vs. Include_Once in PHP: When Should You Use Each?

Understanding the Differences Between Require, Include, Require_Once, and Include_Once in PHP

PHP provides various mechanisms for including external files into your scripts: require, include, require_once, and include_once. Understanding their differences is crucial for efficient and reliable code execution.

Q1: When to Use 'require' vs. 'include'?

The primary distinction between require and include lies in their error handling. If an error occurs while attempting to include a file using include, it will trigger a warning but allow the script to continue execution. However, require will generate a fatal error, terminating the script immediately.

Q2: When to Use 'require_once' vs. 'require'?

While require and include handle errors differently, require_once operates identically to require except for its behavior when including the same file multiple times. require_once checks if the file has already been included and, if so, skips the inclusion process, preventing the file from being executed multiple times.

Note Regarding '_once' Variants

In современном PHP, the use of _once variants (require_once and include_once) has become less common. If you find yourself relying on them, it may indicate the need for code restructuring or a mindless habit.

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