1. It's useful when you want to check the exact under-the-hood behavior, to figure out side-effects or corner-case semantics.
2. After a good number of years, that code becomes less scary and more icky. Some of it remains kind of scary though...
3. Reading that code teaches you a lot about considerations you may be ignoring, especially your implicit platform-dependent assumptions.
4. Nitpick: There isn't any single C++ standard library source code, it's at least 3 popular ones (GCC's libstdc++, LLVM's libc++, and Microsoft's)
1. It's useful when you want to check the exact under-the-hood behavior, to figure out side-effects or corner-case semantics.
2. After a good number of years, that code becomes less scary and more icky. Some of it remains kind of scary though...
3. Reading that code teaches you a lot about considerations you may be ignoring, especially your implicit platform-dependent assumptions.
4. Nitpick: There isn't any single C++ standard library source code, it's at least 3 popular ones (GCC's libstdc++, LLVM's libc++, and Microsoft's)