C++Talk.NET C++ language newsgroups   Archives   FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in to check your private messages   Log in  sizeof(int) Goto page 1, 2  Next          C++Talk.NET Forum Index -> C++ language (comp.lang.c++) View previous topic :: View next topic   Author Message Richard Cavell Guest Posted: Sat Feb 26, 2005 9:45 am    Post subject: sizeof(int) Hi, Is there some kind of canonical list, or would someone like to give a brief rundown, as to: sizeof(int) sizeof(long int) sizeof(long long) etc or perhaps even the vector types, for current hardware (Pentium 4/Athlon/G4/G5/Playstation 3/etc) used with current compilers? Or perhaps a list of what size int_t you can define and expect the processor to handle natively? Back to top Victor Bazarov Guest Posted: Sat Feb 26, 2005 4:03 pm    Post subject: Re: sizeof(int) "Richard Cavell" <richardcavell (AT) mail (DOT) com> wrote... Quote: Is there some kind of canonical list, or would someone like to give a brief rundown, as to: sizeof(int) sizeof(long int) sizeof(long long) etc sizeof(int) is the size of an int object expressed in bytes. sizeof(long int) is the size of a long int object. sizeof(long long) is a syntax error since C++ has no "long long" type. I am not sure what "canonical list" you're talking about. Quote: or perhaps even the vector types, for current hardware (Pentium 4/Athlon/G4/G5/Playstation 3/etc) used with current compilers? Or perhaps a list of what size int_t you can define and expect the processor to handle natively? If you need something compiler-specific, please ask in a newsgroup dedicated to that compiler. C++ discussed here is compiler-independent. If you need something hardware-specific, please ask in a newsgroup dedicated to that hardware. C++ is a hardware-independent language. V Back to top Richard Cavell Guest Posted: Sun Feb 27, 2005 1:04 am    Post subject: Re: sizeof(int) On 27/2/05 3:03 AM, Victor Bazarov wrote: Quote: C++ is a hardware-independent language. No, it ain't. I have to write my program differently depending on what these sizeofs are. So it's not hardware-independent at all. Back to top Victor Bazarov Guest Posted: Sun Feb 27, 2005 3:28 am    Post subject: Re: sizeof(int) "Richard Cavell" <richardcavell (AT) mail (DOT) com> wrote... Quote: On 27/2/05 3:03 AM, Victor Bazarov wrote: C++ is a hardware-independent language. No, it ain't. I have to write my program differently depending on what these sizeofs are. So it's not hardware-independent at all. It's not the language, silly. It's your algorithm, it's what you want to do, that makes it hardware-dependent. Back to top DHOLLINGSWORTH2 Guest Posted: Sun Feb 27, 2005 4:55 am    Post subject: Re: sizeof(int) "Richard Cavell" <richardcavell (AT) mail (DOT) com> wrote Quote: Hi, Is there some kind of canonical list, or would someone like to give a brief rundown, as to: sizeof(int) sizeof(long int) sizeof(long long) etc or perhaps even the vector types, for current hardware (Pentium 4/Athlon/G4/G5/Playstation 3/etc) used with current compilers? Or perhaps a list of what size int_t you can define and expect the processor to handle natively? usually an int is the size of the register used, on the 286 this was 16 bits, a long was 32. on 386 protected, 486, int is 32 bits, and long int, is 32 bits as well, Double Word is 64 bits. A char is always 8 bits. The ratio of Char size to int size will tell you the hardware type, ie the register width. Back to top Shezan Baig Guest Posted: Sun Feb 27, 2005 5:00 am    Post subject: Re: sizeof(int) DHOLLINGSWORTH2 wrote: Quote: A char is always 8 bits. Why can't a char be 16 bits? Back to top Richard Cavell Guest Posted: Sun Feb 27, 2005 5:13 am    Post subject: Re: sizeof(int) On 27/2/05 2:28 PM, Victor Bazarov wrote: Quote: "Richard Cavell" <richardcavell (AT) mail (DOT) com> wrote... On 27/2/05 3:03 AM, Victor Bazarov wrote: C++ is a hardware-independent language. No, it ain't. I have to write my program differently depending on what these sizeofs are. So it's not hardware-independent at all. It's not the language, silly. It's your algorithm, it's what you want to do, that makes it hardware-dependent. That makes no sense at all. If C++ ran inside a virtual machine then it wouldn't matter to me whether my processor could do 16-bit integers at a time, or 32, or whatever. But my program actually does different things based on sizeof(int) whether I want it to or not. Back to top Jonathan Turkanis Guest Posted: Sun Feb 27, 2005 5:27 am    Post subject: Re: sizeof(int) Richard Cavell wrote: Quote: On 27/2/05 2:28 PM, Victor Bazarov wrote: "Richard Cavell" <richardcavell (AT) mail (DOT) com> wrote... On 27/2/05 3:03 AM, Victor Bazarov wrote: C++ is a hardware-independent language. No, it ain't. I have to write my program differently depending on what these sizeofs are. So it's not hardware-independent at all. It's not the language, silly. It's your algorithm, it's what you want to do, that makes it hardware-dependent. That makes no sense at all. If C++ ran inside a virtual machine then it wouldn't matter to me whether my processor could do 16-bit integers at a time, or 32, or whatever. But my program actually does different things based on sizeof(int) whether I want it to or not. The following is a hardware-dependent program, in your sense: #include <iostream> int main() { if (sizeof(int) == 19) std::cout << "hello 19 worldn"; else std::cout << "hello non-19 worldn"; } Is this what bothers you? You don't want your program to be able to detect anything that varies from system to system? It would be more worthwile to ask about ways to write programs which work on a variety of platforms. There are lots of ways to do it. Jonathan Back to top Shezan Baig Guest Posted: Sun Feb 27, 2005 5:28 am    Post subject: Re: sizeof(int) Richard Cavell wrote: Quote: On 27/2/05 2:28 PM, Victor Bazarov wrote: It's not the language, silly. It's your algorithm, it's what you want to do, that makes it hardware-dependent. That makes no sense at all. If C++ ran inside a virtual machine then it wouldn't matter to me whether my processor could do 16-bit integers at a time, or 32, or whatever. But my program actually does different things based on sizeof(int) whether I want it to or not. What exactly is your program trying to do? A portable program should not need to depend on sizeof(int) being a certain size, unless you're doing some form of externalization. Back to top Phil Staite Guest Posted: Sun Feb 27, 2005 6:20 am    Post subject: Re: sizeof(int) Richard Cavell wrote: Quote: On 27/2/05 2:28 PM, Victor Bazarov wrote: That makes no sense at all. If C++ ran inside a virtual machine then it wouldn't matter to me whether my processor could do 16-bit integers at a time, or 32, or whatever. But my program actually does different things based on sizeof(int) whether I want it to or not. Then I suggest you have sizeof(int) in your program, such as: if( sizeof(int) == 2 ) { // oh schnitt, a 16 bit machine!!! } else if( sizeof(int) == 4 ) { // ahh, mainstream life... } else if( sizeof(int) == 8 ) { // where the {expletive} am I now? } If you're curious on your machine, just dump them: #include<iostream> int main( int argc, char* argv[] ) { std::cout << "int " << sizeof(int) << std::endl; std::cout << "long " << sizeof(long) << std::endl; return 0; } Back to top Ron Natalie Guest Posted: Sun Feb 27, 2005 2:53 pm    Post subject: Re: sizeof(int) Shezan Baig wrote: Quote: DHOLLINGSWORTH2 wrote: A char is always 8 bits. Why can't a char be 16 bits? It can be, but it is unlikely. Unfortunately one of the great defects in C++ is that char has a double role: that of the basic character AND that of the smallest addressable storage unit. Ideally, bytes and characters should be dissassociated. Back to top Victor Bazarov Guest Posted: Sun Feb 27, 2005 3:39 pm    Post subject: Re: sizeof(int) "Ron Natalie" <ron (AT) sensor (DOT) com> wrote... Quote: Shezan Baig wrote: DHOLLINGSWORTH2 wrote: A char is always 8 bits. Why can't a char be 16 bits? It can be, but it is unlikely. Unfortunately one of the great defects in C++ is that char has a double role: that of the basic character AND that of the smallest addressable storage unit. Ideally, bytes and characters should be dissassociated. I think you misunderstand the role of a char WRT basic character set. Nothing prevents a 32-bit char from containing an element from the basic character set. The requirement is only that the char type to be large enough for that. There is no requirement that it has to be no larger than necessary to contain the basic characters. There is no defect in the language, only in your understanding of it. V Back to top Carl Muller Guest Posted: Sun Feb 27, 2005 4:41 pm    Post subject: Re: sizeof(int) "DHOLLINGSWORTH2" <DHOLLINGSWORTH2 (AT) cox (DOT) net> wrote Quote: "Richard Cavell" <richardcavell (AT) mail (DOT) com> wrote in message news:cvpg29$3ai$1 (AT) nnrp (DOT) waia.asn.au... [snip] A char is always 8 bits. The ratio of Char size to int size will tell you the hardware type, ie the register width. Not always. A char is at least 8 bits, but on the hardware I program it is 16 bits (as is int, so sizeof(int)==1). There are other chip manufacturers in the world than Intel you know. Back to top Jerry Coffin Guest Posted: Sun Feb 27, 2005 6:09 pm    Post subject: Re: sizeof(int) Richard Cavell wrote: [ ... ] Quote: That makes no sense at all. If C++ ran inside a virtual machine then it wouldn't matter to me whether my processor could do 16-bit integers at a time, or 32, or whatever. But my program actually does different things based on sizeof(int) whether I want it to or not. If you need something you're certain is at least 32 bits, use long. If you need something you need to be certain is only 16 bits, use a bitfield. In the end, you're right: running in a VM could provide greater isolation from the hardware, and with it greater portability. OTOH, you need to use SOME language to implement the VM, and the operating system it runs on, and he device drivers IT uses to talk to the hardware -- and right now, the languages of choice for all those things UNDER the VM are C and C++. If you insist on them running inside of the VM, you have to come up with something else to implement all the other things under the VM. Based on experience, I'd put the chances at roughly 99% that if you attempted to create a language to replace C and C++ in those roles, you'd end up with something that did NOT provide as good of a tradeoff between portability and access to the hardware as C and C++ provide right now. Of all the gazillions of attempts at such programming languages, there's only about _one_ that's really competitive with C or C++ for these tasks. -- Later, Jerry. The universe is a figment of its own imagination. Back to top Ioannis Vranos Guest Posted: Sun Feb 27, 2005 6:21 pm    Post subject: Re: sizeof(int) Richard Cavell wrote: Quote: That makes no sense at all. If C++ ran inside a virtual machine then it wouldn't matter to me whether my processor could do 16-bit integers at a time, or 32, or whatever. But my program actually does different things based on sizeof(int) whether I want it to or not. I do not think the VM makes the difference you are thinking it does. A VM is a machine as its name implies with its own assembly language. For example, .NET is a CLI VM and here is a book about .NET's (CLI) VM assembly language: http://www.amazon.com/exec/obidos/tg/detail/-/0735615470/qid=1091414100/sr=1-7/ref=sr_1_7/102-2992266-3703320?v=glance&s=books CLI assembly language is defined in the freely available CLI standard, so you can view in the specification how it looks like: http://www.ecma-international.org/publications/standards/Ecma-335.htm -- Ioannis Vranos http://www23.brinkster.com/noicys 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 (comp.lang.c++) All times are GMT Goto page 1, 2  Next Page 1 of 2   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.