Why does `include <iostream>` end, including so many * files?

Question

Follow this question :

When i do include <iostream>.
It happens that it includes many files from /usr/include.A grep "\usr\include"over g++ -E prog.cpp, counted approximately 1260 records;).

Is their way to control including various files?
Platform: Linux
g ++ Version: 4.2.4

Answer 1

No, it <iostream>includes them, because they depend on them directly, or the dependencies depend on them.

There is nothing you can do about it.

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Answer 2

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Answer 3

You #include <iostream>when you need to use threads. This should determine some of the things you need. What kind of activity he should carry out is a problem of quality of implementation. You can delete files from /usr/include, but it can break things.

I really doubt it, including 1260 files. Most likely, most of them are duplicate entries that do not load anything, but are not clipped from the output -E.