How to find the source code of classes in c++
 

in c++ , i am using classes but the problem is , that how to find that which class is extended by another class .

example ..... how to find , that which classes are extended by <iostream>

and , why bool boolalpha is added in <ios> !

Do you mean, how do I find which of the source files #include <iostream> (for example)? Unless I misunderstand you, classes are not extended by other classes (well, not in the way you suggest by the example '<iostream>'), you use the #include directive at the start of the file. In which case

should give you the files which include iostream, if you run it in the project's root directory.