What language are inbuilt PHP functions written in?

Question

This may sound like a stupid question but I\'m a beginner not just to PHP but to programming in general, so in that context:

What language are inbuilt PHP functions writ

Answer 1

PHP was written in C. Any language above machine code for the specific processor architecture is written in a lower-level language. These abstractions into higher-level languages are an effort to make programming simpler and more productive.