Why should I not include cpp files and instead use a header?

Question

So I finished my first C++ programming assignment and received my grade. But according to the grading, I lost marks for including cpp files instead of compiling and li

Answer 1

If it works for you then there is nothing wrong with it -- except that it will ruffle the feathers of people who think that there is only one way to do things.

Many of the answers given here address optimizations for large-scale software projects. These are good things to know about, but there is no point in optimizing a small project as if it were a large project -- that is what is known as "premature optimization". Depending on your development environment, there may be significant extra complexity involved in setting up a build configuration to support multiple source files per program.

If, over time, your project evolves and you find that the build process is taking too long, then you can refactor your code to use multiple source files for faster incremental builds.

Several of the answers discuss separating interface from implementation. However, this is not an inherent feature of include files, and it is quite common to #include "header" files that directly incorporate their implementation (even the C++ Standard Library does this to a significant degree).

The only thing truly "unconventional" about what you have done was naming your included files ".cpp" instead of ".h" or ".hpp".