-lstdc ++和-lstdc ++ 11之间的区别

Question

Which standards gets invoked by invoking compiler flag "-lstdc++"? Like with "-lstdc++11", the c++11 standard gets invoked and the same can be called by "-std=c++11".

Answer 1

The -l flag does not change standards conformance, it is used to specify what libraries to link with.

So, -lstdc++ would link with a library named libstdc++.a or libstdc++.so . On my system, that library can be found at /usr/lib/x86_64-linux-gnu/libstdc++.so.6 , but it will generally be different on your system.

This is no different from specifying something like -lSDL , which links with libSDL.so , or specifying -lpng , which links with libpng.so .

If you want to use a certain version of the C++ standard, use the -std option (like -std=c++11 ). This will also link the correct library in, so you do not need to do anything else (such as use any -l options).

Answer 2

You don't specify the compiler here, but let's assume it is clang++ or g++ or something similar.

Then the flag -l<library> simply specifies that the library <library> should be searched when linking. This search will include a standard list of search directories and others that may have been added to the library path.

Thus the flag -lstdc++ simply indicates that library should be searched at link time. It has no effect on the version of c++ that the compiler should think it is compiling.

In contrast, the flag -std=c++ generally acts as switch to the compiler that:

• indicates the version of c++ in use;
• automatically causes the corresponding library and include paths to be added to the search paths