C++ standard library - when should I use it and when shouldn't I?

Question

I was wondering how often people actually use much of the standard c++ library, particularly the stuff in the and

Answer 1

What projects are you sifting through? Are these professional projects or something random?

One of the things I've noticed is that a lot of legacy type code (I worked on a code base that pre-dated C++98) avoids the C++ standard library because of performance worries of the implementations at that time, or just because the libraries didn't exist at the time. Of course, some environments (embedded systems, games, defense, etc.) might have other requirements that preclude the use of C++ standard library in many cases, like a coworker of mine worked in defense and couldn't use the STL stuff at all, due to customer requirements not to use it.

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In general, if there's a choice of using the standard library vs. inventing your own wheel vs. using someone else's library, then in general I'd pick the first choice first. The code gets tested by thousands, hundreds of thousands of people, subject to more testing and scrutiny than most things you'd implement yourself.

A third party library (let's pick an example like Boost) if it has things that you require. A library like Boost is well respected, has a reputation of being exceptional quality code, and is used/tested/maintained by many, many people.

The final choice is invention of your own code, I think this really falls into a few categories:

1. Self-learning - writing code just to learn, but this means there's no expectation you're shipping it as production code.
2. You have specific requirements that are not met by anything that can be acquired, or must be adapted from something else. There is a lot of this, you might need to write your own algorithms specific to whatever you're doing.

But remember that if you implement your own, think about whether or not the standard library already has it, otherwise you could run into a maintenance problem if something gets very ingrained in your code. My last company implemented their own container classes, and of course the code base grew to millions of lines of code (across tons of products) and everyone used these internally-developed container classes. Bugs in those containers cost significant amounts of developer time and money to fix because there were just fundamental bugs in the classes (linked lists, vectors, associative arrays, nothing that standard C++ doesn't provide). While new code used the standard library, the company just didn't have the resources to start refactoring all the old code.

If you can offload that worry to other developers who are experienced with such code, AND get the testing of thousands of people? That's a big win!