//cpeer.h #ifndef CPEER_H_ #define CPEER_H_ #include <string> struct CPeer { std::string name; }; #endif /*CPEER_H_*/ //cpeermanager.h #ifndef CPEERMANAGER_H_ #define CPEERMANAGER_H_ class CPeer; #include <boost/shared_ptr.hpp> #include <boost/scoped_ptr.hpp> class CPeerManager { public: CPeerManager(); boost::scoped_ptr<CPeer> cp_; //error // boost::shared_ptr<CPeer> cp_; // ok }; #endif /*CPEERMANAGER_H_*/ //cpeermanager.cpp #include "cpeer.h" #include "cpeermanager.h" CPeerManager::CPeerManager(): cp_ (new CPeer() ) { } //main.cpp #include "cpeermanager.h" int main() { CPeerManager cp; } i get **** Build of configuration Debug for project scoped_ptr_test **** make -k all 'Building file: ../cpeermanager.cpp' 'Invoking: GCC C++ Compiler' g++ -O0 -g3 -Wall -c -fmessage-length=0 -MMD -MP -MF"cpeermanager.d" -MT"cpeermanager.d" -o"cpeermanager.o" "../cpeermanager.cpp" 'Finished building: ../cpeermanager.cpp' ' ' 'Building file: ../main.cpp' 'Invoking: GCC C++ Compiler' g++ -O0 -g3 -Wall -c -fmessage-length=0 -MMD -MP -MF"main.d" -MT"main.d" -o"main.o" "../main.cpp" c:/mingw/bin/../lib/gcc/i686-pc-mingw32/4.1.2/../../../../include/boost/checked_delete.hpp: In function 'void boost::checked_delete(T*) [with T = CPeer]': c:/mingw/bin/../lib/gcc/i686-pc-mingw32/4.1.2/../../../../include/boost/scoped_ptr.hpp:77: instantiated from 'boost::scoped_ptr<T>::~scoped_ptr() [with T = CPeer]' ../cpeermanager.h:11: instantiated from here c:/mingw/bin/../lib/gcc/i686-pc-mingw32/4.1.2/../../../../include/boost/checked_delete.hpp:32: error: invalid application of 'sizeof' to incomplete type 'CPeer' c:/mingw/bin/../lib/gcc/i686-pc-mingw32/4.1.2/../../../../include/boost/checked_delete.hpp:32: error: creating array with negative size ('-0x000000001') c:/mingw/bin/../lib/gcc/i686-pc-mingw32/4.1.2/../../../../include/boost/checked_delete.hpp:33: error: invalid application of 'sizeof' to incomplete type 'CPeer' c:/mingw/bin/../lib/gcc/i686-pc-mingw32/4.1.2/../../../../include/boost/checked_delete.hpp:33: error: creating array with negative size ('-0x000000001') c:/mingw/bin/../lib/gcc/i686-pc-mingw32/4.1.2/../../../../include/boost/checked_delete.hpp:34: warning: possible problem detected in invocation of delete operator: c:/mingw/bin/../lib/gcc/i686-pc-mingw32/4.1.2/../../../../include/boost/checked_delete.hpp:29: warning: 'x' has incomplete type ../cpeermanager.h:4: warning: forward declaration of 'struct CPeer' c:/mingw/bin/../lib/gcc/i686-pc-mingw32/4.1.2/../../../../include/boost/checked_delete.hpp:34: note: neither the destructor nor the class-specific operator delete will be called, even if they are declared when the class is defined. make: *** [main.o] Error 1 make: Target `all' not remade because of errors. Build complete for project scoped_ptr_test /// why boost::shared_ptr can used to Minimize compilation dependencies between files, yet boost::scoped_ptr cannot. I needn't to use reference cout.may someboby help me out of the trouble.thanks! iPod、万 点 巨 额 点 卡、奖 学 金……海 量 奖 品，想 拿 就 拿！