C++Talk.NET C++ language newsgroups   Archives   FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in to check your private messages   Log in  How to delete an array?          C++Talk.NET Forum Index -> C++ language (comp.lang.c++) View previous topic :: View next topic   Author Message felixnielsen@hotmail.com Guest Posted: Sun Jan 22, 2006 5:40 pm    Post subject: How to delete an array? Hi, im pretty new to this so plz cut me some slag ;-) anyhow, i need to delete an array, or what i really need is to increase the array size, i was think i could be done by copying the array into a temorary array of the same size, then delete the original, initiate the old array again, but now with more spaces/cell or what u call it, then copy the teporary array into the on just created and last delete the temp array. a bit complicated, but im told its the only way to do it... Back to top TB Guest Posted: Sun Jan 22, 2006 5:55 pm    Post subject: Re: How to delete an array? [email]felixnielsen (AT) hotmail (DOT) com[/email] sade: Quote: Hi, im pretty new to this so plz cut me some slag ;-) anyhow, i need to delete an array, or what i really need is to increase the array size, i was think i could be done by copying the array into a temorary array of the same size, then delete the original, initiate the old array again, but now with more spaces/cell or what u call it, then copy the teporary array into the on just created and last delete the temp array. a bit complicated, but im told its the only way to do it... Here you go: int main(int argc, char* argv[]) { // The array which to extend int * iptr = new int[5]; // Allocate new array int * temp = new int[8]; // Copy iptr to nptr for(unsigned i = 0; i < 5; ++i) { temp[i] = iptr[i]; } // Delete old array delete[] iptr; // Repoint iptr to new array iptr = temp; temp = 0; // Delete array delete[] iptr; return 0; } Or just use std::vector instead and you won't have to deal with the above. -- TB @ SWEDEN Back to top Ralph Guest Posted: Sun Jan 22, 2006 6:04 pm    Post subject: Re: How to delete an array? <felixnielsen (AT) hotmail (DOT) com> wrote Quote: Hi, im pretty new to this so plz cut me some slag ;-) anyhow, i need to delete an array, or what i really need is to increase the array size, i was think i could be done by copying the array into a temorary array of the same size, then delete the original, initiate the old array again, but now with more spaces/cell or what u call it, then copy the teporary array into the on just created and last delete the temp array. a bit complicated, but im told its the only way to do it... Take a look at the Standard C++ library - vector::resize() There are reasons C++ provides sequence containers. -ralph Back to top felixnielsen@hotmail.com Guest Posted: Sun Jan 22, 2006 6:36 pm    Post subject: Re: How to delete an array? is i wrote, im pwer new to this and i must admit that i dont have a complete understanding of all the above exprissions, howefer thanks for the answer ill take a look at it and return in case i cant get it to work. Back to top Mike Wahler Guest Posted: Sun Jan 22, 2006 7:23 pm    Post subject: Re: How to delete an array? <felixnielsen (AT) hotmail (DOT) com> wrote Quote: Hi, im pretty new to this so plz cut me some slag ;-) anyhow, i need to delete an array, or what i really need is to increase the array size, i was think i could be done by copying the array into a temorary array of the same size, then delete the original, initiate the old array again, but now with more spaces/cell or what u call it, then copy the teporary array into the on just created and last delete the temp array. a bit complicated, but im told its the only way to do it... Eliminate complications by not using an array, use a std::vector instead. It can grow and shrink in size automatically, relieving you of all memory management issues. -Mike Back to top felixnielsen@hotmail.com Guest Posted: Sun Jan 22, 2006 7:34 pm    Post subject: Re: How to delete an array? yes, very neat, i just read a little guide about it, really very simple endless theres something i have missunderstod. there is one thing though. With arrays you can assign a value to af "cell" that doesnt excist, not very smart i know, however you can do the same with vector i found out, is there any complications i should know about? Back to top Mike Wahler Guest Posted: Sun Jan 22, 2006 7:50 pm    Post subject: Re: How to delete an array? <felixnielsen (AT) hotmail (DOT) com> wrote Quote: yes, very neat, i just read a little guide about it, really very simple endless theres something i have missunderstod. there is one thing though. With arrays you can assign a value to af "cell" that doesnt excist, You can indeed write syntactically correct code to do this, but its behavior is undefined (i.e. anything might happen, from 'seems to work', to a crash, or anything else.) Quote: not very smart i know, Nope. Quote: however you can do the same with vector i found out, No you cannot. Undefined behavior will also be the result. If you want to put additional elements in a vector, use its 'insert' or 'push_back' member functions (or 'resize()', which (if the specified size is greater than existing size), will append the necessary number of default- initialized elements to bring the size to that specified.. Quote: is there any complications i should know about? C++ is rather complicated. I suggest the best way to deal with that is to get some good books. See www.accu.org for suggestions. -Mike Back to top felixnielsen@hotmail.com Guest Posted: Sun Jan 22, 2006 9:50 pm    Post subject: Re: How to delete an array? well, i got it working, however i am having trouble using vectors in functions, probably because the vector is declaret the wrong place or something like that, but is it at all posible to declare global vectors? Back to top Gavin Deane Guest Posted: Sun Jan 22, 2006 10:09 pm    Post subject: Re: How to delete an array? [email]felixnielsen (AT) hotmail (DOT) com[/email] wrote: Quote: well, i got it working, however i am having trouble using vectors in functions, probably because the vector is declaret the wrong place or something like that, but is it at all posible to declare global vectors? It is possible, but it's not good design to use global variables. Passing vectors to functions is not difficult and is a much better idea. You've obviously had a go at writing the code but you're having problems. Post the code here and people will be able to show you what's wrong. Note these guidelines for posting code: http://www.parashift.com/c++-faq-lite/how-to-post.html#faq-5.8 If you follow the advice there, so that people can copy and paste directly from your message into their compiler, you should get the help you need. Gavin Deane Back to top Luke Meyers Guest Posted: Sun Jan 22, 2006 10:17 pm    Post subject: Re: How to delete an array? [email]felixnielsen (AT) hotmail (DOT) com[/email] wrote: Quote: well, i got it working, however i am having trouble using vectors in functions, probably because the vector is declaret the wrong place or something like that, but is it at all posible to declare global vectors? Yes, but don't do that. The Right Way to make a variable (such as a vector) visible to a function is to pass it in (by value, or by reference -- learn the difference, it's important!) as an argument. Or, where appropriate to the design, the vector could be member data, and the function a member function, of some class which encapsulates the logical entity whose behavior and state are being represented. Member functions automatically have access to member data. It's nifty like that. Don't be afraid to post code if you get confused. The STL is freakin' rad and all, but as with any powerful tool (e.g. tools involving sharp metal moving at high speed), there is a learning curve, and some guidance is generally advisable. Luke 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 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.