C++Talk.NET C++ language newsgroups   Archives   FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in to check your private messages   Log in  about "volatile int*"          C++Talk.NET Forum Index -> C++ Language (Moderated) View previous topic :: View next topic   Author Message bruceteen@gmail.com Guest Posted: Fri Sep 09, 2005 3:26 pm    Post subject: about "volatile int*" I am a chinese£¬My english is poor, sorry. // use g++3.4.2 #include <iostream> using namespace std; int main( void ) { volatile int k=0; cout<< &k < cout << typeid(bool).name() << endl; // b cout << typeid(int*).name() << endl; // Pi cout << typeid(volatile int*).name() << endl; // PVi cout << typeid(&k).name() << endl; // PVi system("PAUSE"); return EXIT_SUCCESS; } ^_^ [ See http://www.gotw.ca/resources/clcm.htm for info about ] [ comp.lang.c++.moderated. First time posters: Do this! ] Back to top Thomas Tutone Guest Posted: Sat Sep 10, 2005 12:39 am    Post subject: Re: about "volatile int*" [email]bruceteen (AT) gmail (DOT) com[/email] wrote: Quote: #include <iostream using namespace std; int main( void ) { volatile int k=0; cout<< &k < Replace the above line with this: cout << static_cast The problem, apparently, is that there is no overloaded operator<< that accepts a volatile int*, but there is an overloaded operator<< that takes a bool. So, your pointer gets converted to a bool, and unless you change the formatting flags, a bool true gets output as "1". To fix it, you first have to cast away the volatile part, using const_cast<>, then cast it into a void*, using static_cast<>. Best regards, Tom [ See http://www.gotw.ca/resources/clcm.htm for info about ] [ comp.lang.c++.moderated. First time posters: Do this! ] Back to top Ron Natalie Guest Posted: Sat Sep 10, 2005 12:41 am    Post subject: Re: about "volatile int*" [email]bruceteen (AT) gmail (DOT) com[/email] wrote: Quote: I am a chinese£¬My english is poor, sorry. // use g++3.4.2 #include <iostream using namespace std; int main( void ) { volatile int k=0; cout<< &k < Because the thing that prints addresses for pointers takes a void*. You can't implicity convert from volatile int* to void* (violates the CV qualification). cout << (void*)&k << endl; will hack it (or prehaps better): cout << const_cast cast away the volatile. [ See http://www.gotw.ca/resources/clcm.htm for info about ] [ comp.lang.c++.moderated. First time posters: Do this! ] Back to top Ben Hutchings Guest Posted: Sat Sep 10, 2005 12:42 am    Post subject: Re: about "volatile int*" [email]bruceteen (AT) gmail (DOT) com[/email] <bruceteen (AT) gmail (DOT) com> wrote: Quote: I am a chinese£¬My english is poor, sorry. // use g++3.4.2 #include <iostream using namespace std; int main( void ) { volatile int k=0; cout<< &k < snip There is a standard conversion from volatile int * to bool, but not from volatile int * to const void *, so the only viable candidate for operator<< here is the one which takes a bool. Since &k is non-null, the result of conversion to bool is true, which is printed as 1. Ben. -- Ben Hutchings Having problems with C++ templates? Your questions may be answered by [ See http://www.gotw.ca/resources/clcm.htm for info about ] [ comp.lang.c++.moderated. First time posters: Do this! ] Back to top Display posts from previous: All Posts1 Day7 Days2 Weeks1 Month3 Months6 Months1 Year Oldest FirstNewest First         C++Talk.NET Forum Index -> C++ Language (Moderated) All times are GMT Page 1 of 1   Jump to: Select a forum C/C++----------------C LanguageC Language (Moderated)C++ Language (Moderated)C++ language (comp.lang.c++)C++ language, library and standards Non-English C/C++ Newsgroups----------------C++ (German)C++ (French)  You cannot post new topics in this forum You cannot reply to topics in this forum You cannot edit your posts in this forum You cannot delete your posts in this forum You cannot vote in polls in this forum Powered by phpBB © 2001, 2006 phpBB Group SEO toolkit © 2004-2006 webmedic.