PHP Case Conversion Mastery: `strtolower()` vs. `mb_strtolower()` - Are You Using the Right One?

Converting uppercase strings to lowercase is a fundamental task in PHP development. This guide provides a deep dive into PHP's three core case conversion functions: `strtolower()`, `mb_strtolower()`, and `lcfirst()`. Through code examples and scenario analysis from author DP, we'll help you understand their differences, performance implications, and best practices, ensuring you make the right choice when handling user input or internationalized projects.