codeforce能用万能头文件吗_C语言能不能使用万能头文件啊，如果可以应该怎么使用啊？...

并不是所有的编译器都支持万能头，也不是 C++标准的一部分。

并不建议使用万能头，因为它会包含很多不必要的头文件，增加编译时间，好好学习每个头文件都包含哪些东西，而不是总想着投机取巧。

如果比赛中的话，可以用用，减少工作量。

It is basically a header file that also includes every standard library and STL include file. The only purpose I can see for it would be for testing and education.

Se e.g. GCC 4.8.0 /bits/stdc++.h source.

Using it would include a lot of unnecessary stuff and increases compilation time.

Edit: As Neil says, it's an implementation for precompiled headers. If you set it up for precompilation correctly it could, in fact, speed up compilation time depending on your project. (https://gcc.gnu.org/onlinedocs/gcc/Precompiled-Headers.html)

I would, however, suggest that you take time to learn about each of the sl/stl headers and include them separately instead, and not use "super headers" except for precompilation