What’s the difference between a header file and a library?

by

Think of both like this (Disclaimer: this is a really high-level analogy 😉 ..

  • The header is a phone number you can call, while…
  • …the library is the actual person you can reach there!

It’s the fundamental difference between “interface” and “implementation”; the interface (header) tells you how to call some functionality (without knowing how it works), while the implementation (library) is the actual functionality.

Note: The concept is so fundamental, because it allows you flexibility: you can have the same header for different libraries (i.e. the functionality is exactly called in the same way), and each library may implement the functionality in a different way. By keeping the same interface, you can replace the libraries without changing your code.

And: you can change the implementation of the library without breaking the calling code!

More Related Contents:

  1. Why QFile(“./test”) work though [Class QFile] has no QFile(char* s) constructor
  2. While loop using &&
  3. Calling virtual functions inside constructors
  4. How to convert an instance of std::string to lower case
  5. Post-increment and Pre-increment concept?
  6. Can someone explain this template code that gives me the size of an array? [duplicate]
  7. How to correctly implement custom iterators and const_iterators?
  8. Does the C++ standard mandate poor performance for iostreams, or am I just dealing with a poor implementation?
  9. Why don’t C++ compilers define operator== and operator!=?
  10. Should I compile with /MD or /MT?
  11. Difference between erase and remove
  12. Alternative virtual function calls implementations?
  13. Is stateful metaprogramming ill-formed (yet)?
  14. Receiving Chunked HTTP Data With Winsock
  15. When is it necessary to use the flag -stdlib=libstdc++?
  16. Change default value of CMAKE_CXX_FLAGS_DEBUG and friends in CMake
  17. Can I pass std::string to a DLL?
  18. Round double to 3 points decimal [duplicate]
  19. Scoped using-directive within a struct/class declaration? [duplicate]
  20. Why can’t static_cast be used to down-cast when virtual inheritance is involved?
  21. Should every class have a virtual destructor?
  22. Boost::Spirit Expression Parser
  23. What is the proper way to securely disconnect an asio SSL socket?
  24. Why is std::cout so time consuming?
  25. Can you have a triple minus signs in C programming? What does it mean? [duplicate]
  26. Why are the return values of these doubles -1.#IND?
  27. How to sort a linked list using bubble-sort?
  28. Cannot open include file: ‘stdio.h’ – Visual Studio Community 2017 – C++ Error
  29. C/C++ JSON parser [closed]
  30. Debug and Release Library Linking with CMAKE (VISUAL STUDIO)

Leave a Comment