C++Talk.NET C++ language newsgroups   Archives   FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in to check your private messages   Log in  please help me...          C++Talk.NET Forum Index -> C++ language (comp.lang.c++) View previous topic :: View next topic   Author Message Pat Guest Posted: Sat Mar 06, 2004 4:30 pm    Post subject: please help me... Hi, I want to use "new" to build an array test[1000][1000]. Can you tell me how to do? Thank. Pat Back to top Pat Guest Posted: Sat Mar 06, 2004 4:30 pm    Post subject: Re: please help me... I don't want to use "int test[1000][1000]". Thanks. "Pat" <Pat (AT) Pat (DOT) com> ¦b¶l¥ó news:4049fc90$1_2 (AT) rain (DOT) i-cable.com ¤¤¼¶¼g... Quote: Hi, I want to use "new" to build an array test[1000][1000]. Can you tell me how to do? Thank. Pat Back to top AirPete Guest Posted: Sat Mar 06, 2004 6:56 pm    Post subject: Re: please help me... Pat wrote: Quote: I don't want to use "int test[1000][1000]". Thanks. "Pat" <Pat (AT) Pat (DOT) com> ¦b¶l¥ó news:4049fc90$1_2 (AT) rain (DOT) i-cable.com ¤¤¼¶¼g... Hi, I want to use "new" to build an array test[1000][1000]. Can you tell me how to do? Thank. Pat Try a jagged vector of vectors: (not compiled) vector<vector arr; arr.resize(1000); for(int i =0;i<1000;++i) arr[i].resize(1000); Then simply: arr[x][y] = 1234; - Pete Back to top osmium Guest Posted: Sat Mar 06, 2004 7:43 pm    Post subject: Re: please help me... Pat writes: Quote: I want to use "new" to build an array test[1000][1000]. Can you tell me how to do? This works. <add boilerplate> void foo(int b[][4]) { cout << b[2][3] << endl; } void test() { int(*a)[4] = new int[3][4]; a[2][3] = 1024; foo(a); } Back to top Mike Wahler Guest Posted: Sat Mar 06, 2004 7:58 pm    Post subject: Re: [FAQ] please help me... "Pat" <Pat (AT) Pat (DOT) com> wrote Quote: Hi, I want to use "new" to build an array test[1000][1000]. Can you tell me how to do? http://www.parashift.com/c++-faq-lite/freestore-mgmt.html#faq-16.15 Always check the FAQ before posting a question. -Mike Back to top TJB Guest Posted: Sun Mar 07, 2004 8:05 am    Post subject: Re: please help me... "Pat" <Pat (AT) Pat (DOT) com> wrote Quote: Hi, I want to use "new" to build an array test[1000][1000]. Can you tell me how to do? Thank. Pat Hi, You have to create an array of arrays like this: int i,**test; test = new int*[1000]; for (i = 0; i < 1000; i++) test[i] = new int[1000]; You could also start with an array of pointers, int* test[1000], and initialize the elements in it. Back to top Alf P. Steinbach Guest Posted: Sun Mar 07, 2004 8:23 am    Post subject: Re: please help me... * "TJB" <centaurus (AT) telia (DOT) com> schriebt: Quote: "Pat" <Pat (AT) Pat (DOT) com> wrote I want to use "new" to build an array test[1000][1000]. Can you tell me how to do? You have to create an array of arrays like this: int i,**test; test = new int*[1000]; for (i = 0; i < 1000; i++) test[i] = new int[1000]; You could also start with an array of pointers, int* test[1000], and initialize the elements in it. Well no, e doesn't "have to". Except if e _really_ doesn't want a two-dimensional array. See the answer from osmium earlier in the thread about how to allocate a two-dimensional array using new, int (*p)[1000] = new int[1000][1000]; The general question is also a FAQ, see http://www.parashift.com/c++-faq-lite/freestore-mgmt.html#faq-16.15>, "How do I allocate a multidimensional array using new?" Unfortunately, in spite of the heading the FAQ does not show how to allocate a multidimensional array using new (!), only jagged arrays like yours. But it does go on to show a few generally much better ways. -- A: Because it messes up the order in which people normally read text. Q: Why is top-posting such a bad thing? A: Top-posting. Q: What is the most annoying thing on usenet and in e-mail? Back to top LNK2005 Guest Posted: Sun Mar 07, 2004 9:13 am    Post subject: Re: please help me... "osmium" <r124c4u102 (AT) comcast (DOT) net> skrev i meddelandet news:c2d9mi$1q469c$1 (AT) ID-179017 (DOT) news.uni-berlin.de... Quote: Pat writes: int(*a)[4] = new int[3][4]; Maybe you should point out that this only works if the number of items in the second dimension (=4) is known at compile time, which limits the usefullness of this method. 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