C++Talk.NET C++ language newsgroups   Archives   FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in to check your private messages   Log in  typedef decalrations          C++Talk.NET Forum Index -> C++ Language (Moderated) View previous topic :: View next topic   Author Message Andrew Chalk Guest Posted: Mon Sep 15, 2003 9:49 am    Post subject: typedef decalrations I can: typedef char D1; why can't I: typedef char[1400] D2; I.e. declare a typedef corresponding to 1400 bytes. Thanks! [ See http://www.gotw.ca/resources/clcm.htm for info about ] [ comp.lang.c++.moderated. First time posters: Do this! ] Back to top Russell Hanneken Guest Posted: Mon Sep 15, 2003 3:39 pm    Post subject: Re: typedef decalrations "Andrew Chalk" <achalk (AT) XXXmagnacartasoftware (DOT) com> wrote Quote: I can: typedef char D1; why can't I: typedef char[1400] D2; I.e. declare a typedef corresponding to 1400 bytes. You can, but you have to write it like this: typedef char D2[1400]; Regards, Russell Hanneken [email]rhanneken (AT) pobox (DOT) com[/email] [ See http://www.gotw.ca/resources/clcm.htm for info about ] [ comp.lang.c++.moderated. First time posters: Do this! ] Back to top Attila Feher Guest Posted: Mon Sep 15, 2003 3:39 pm    Post subject: Re: typedef decalrations Andrew Chalk wrote: Quote: I can: typedef char D1; why can't I: typedef char[1400] D2; I.e. declare a typedef corresponding to 1400 bytes. You can: typedef char D2[1400]; Just like a variable declaration. -- Attila aka WW [ See http://www.gotw.ca/resources/clcm.htm for info about ] [ comp.lang.c++.moderated. First time posters: Do this! ] Back to top Ivan Vecerina Guest Posted: Mon Sep 15, 2003 3:44 pm    Post subject: Re: typedef decalrations "Andrew Chalk" <achalk (AT) XXXmagnacartasoftware (DOT) com> wrote Quote: I can: typedef char D1; why can't I: typedef char[1400] D2; I.e. declare a typedef corresponding to 1400 bytes. You can, but you have to write it as follows: typedef char D2[1400]; Remember that the expression that follows typedef should always follow the same syntax as a variable declaration. hth -- http://ivan.vecerina.com [ See http://www.gotw.ca/resources/clcm.htm for info about ] [ comp.lang.c++.moderated. First time posters: Do this! ] Back to top Gabriel Dos Reis Guest Posted: Mon Sep 15, 2003 3:46 pm    Post subject: Re: typedef decalrations "Andrew Chalk" <achalk (AT) XXXmagnacartasoftware (DOT) com> writes: Quote: why can't I: typedef char[1400] D2; try typedef char D2[1400]; -- Gabriel Dos Reis <gdr (AT) integrable-solutions (DOT) net> [ 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: Mon Sep 15, 2003 9:54 pm    Post subject: Re: typedef decalrations In article <sC99b.297$xE5.482344098 (AT) newssvr12 (DOT) news.prodigy.com>, Andrew Chalk wrote: Quote: I can: typedef char D1; why can't I: typedef char[1400] D2; I.e. declare a typedef corresponding to 1400 bytes. That isn't normal declarator syntax. You wouldn't declare an object D2 as: char[1400] D2; but instead as: char D2[1400]; With minor exceptions, typedef statements use the same declarator syntax as object and function declarations, so you should write: typedef char D2[1400]; [ See http://www.gotw.ca/resources/clcm.htm for info about ] [ comp.lang.c++.moderated. First time posters: Do this! ] Back to top Dhruv Guest Posted: Mon Sep 15, 2003 9:54 pm    Post subject: Re: typedef decalrations On Mon, 15 Sep 2003 05:49:01 -0400, Andrew Chalk wrote: Quote: I can: typedef char D1; why can't I: typedef char[1400] D2; I.e. declare a typedef corresponding to 1400 bytes. It can, just place the array thing after D2. So, it would change to something like: typedef char D2[1400]; Would make D2 an array of 1400 chars, so using it like this would mean using an array of chars. D2 DObj; Be careful of 1 thing though. If you use new to create a new D2 object, be sure to delete[] it, and not delete it. Regards, -Dhruv. [ See http://www.gotw.ca/resources/clcm.htm for info about ] [ comp.lang.c++.moderated. First time posters: Do this! ] Back to top Marco Manfredini Guest Posted: Mon Sep 15, 2003 10:02 pm    Post subject: Re: typedef decalrations Andrew Chalk wrote: Quote: I can: typedef char D1; why can't I: typedef char[1400] D2; I.e. declare a typedef corresponding to 1400 bytes. try: typedef char D2[14000]; Syntactically, a typedef works like a variable declaration, only that you are declaring a type instead a variable. Marco -- The text above is a result of a bug in my newsreader and I take no responsibility for this text appearing in my post. [ See http://www.gotw.ca/resources/clcm.htm for info about ] [ comp.lang.c++.moderated. First time posters: Do this! ] Back to top Dan McLeran Guest Posted: Tue Sep 16, 2003 6:36 am    Post subject: Re: typedef decalrations Quote: I can: typedef char D1; why can't I: typedef char[1400] D2; I.e. declare a typedef corresponding to 1400 bytes. Thanks! D2 doesn't make much sense. What you're doing is creating an alias for a type, not assigning a size, i.e. you would write: char buffer[1400], not char[1400] buffer. What you can do is something like this: template<unsigned size> struct wrapper { char buffer[size]; }; typedef wrapper<1400> t2; int main() { return 0; } [ See http://www.gotw.ca/resources/clcm.htm for info about ] [ comp.lang.c++.moderated. First time posters: Do this! ] Back to top Francis Glassborow Guest Posted: Tue Sep 16, 2003 1:17 pm    Post subject: Re: typedef decalrations In article <19b0e504.0309151302.67b3b580 (AT) posting (DOT) google.com>, Dan McLeran <dan.r.mcleran (AT) seagate (DOT) com> writes Quote: D2 doesn't make much sense. What you're doing is creating an alias for a type, not assigning a size, i.e. you would write: char buffer[1400], not char[1400] buffer. What you can do is something like this: template<unsigned size struct wrapper { char buffer[size]; }; typedef wrapper<1400> t2; int main() { return 0; } But why not use the simple answer of writing the original declaration correctly: typedef char D2[1400]; ? There is no point in reaching for a Swiss-army knife because you hit your thumb with a hammer instead of the nail. -- Francis Glassborow ACCU 64 Southfield Rd Oxford OX4 1PA +44(0)1865 246490 All opinions are mine and do not represent those of any organisation [ See http://www.gotw.ca/resources/clcm.htm for info about ] [ comp.lang.c++.moderated. First time posters: Do this! ] Back to top Attila Feher Guest Posted: Tue Sep 16, 2003 8:37 pm    Post subject: Re: typedef decalrations Francis Glassborow wrote: [SNIP] Quote: But why not use the simple answer of writing the original declaration correctly: typedef char D2[1400]; Like I did! I am a good boy. Quote: ? There is no point in reaching for a Swiss-army knife because you hit your thumb with a hammer instead of the nail. Hm. Why would I want to hit my thumb with a nail? -- Attila aka WW [ See http://www.gotw.ca/resources/clcm.htm for info about ] [ comp.lang.c++.moderated. 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