Answer
require stops execution if the file is missing, include only warns. require_once and include_once prevent duplicate loading. In real projects, require_once is used for config, autoloaders, and shared logic.
Quick Answer
require causes a fatal error if file not found. include shows a warning but continues. require_once and include_once track loaded files and skip re-loading them. Use require for critical files (classes, config). Use include for optional template parts. The _once variants prevent redeclaration errors. In modern PHP with Composer autoloading, manual includes are rarely needed.
S
SugharaIQ Editorial Team
Verified Answer
This answer has been peer-reviewed by industry experts holding senior engineering roles to ensure technical accuracy and relevance for modern interview standards.
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Source: SugharaIQ