错误C2678:二进制'>>':没有发现哪个操作符的左操作数和类型'std::istream'(或没有可接受的转换)

I found this compiling error very odd . error C2678: binary '>>' : no operator found which takes a left-hand operand of type 'std::istream' (or there is no acceptable conversion) I'm compiling under MVC++ Express 2010 here's the code :I found this compiling error very odd . error C