Here are a number of websites that provide useful information about C++.
Note that many of these websites cover lots of detail, and are formatted to provide information in a very condensed manner. You will often find that information on C++ is widespread, but can be presented in what could be an overwhelming way.
Learn C++ : a free website devoted to teaching you how to program in modern C++.
cplusplus.com : A site providing tutorials, a reference, articles, and a form on C++
C++ Reference : A website providing lots of condensed details about C++
Microsoft C++, C, and Assembler documentation : A reference to C++ (etc.) with a focus on Microsoft’s Visual Studio IDE.
W3Schools C++ Tutorial : A useful site where you can try modifying C++ examples online.