this code is correct in C#
int x = int.Parse(Console.ReadLine());
int[] t = new int[x];
but in c/c++ in wrong
int n; scanf("%d",&n); int a[n];
how in c# static array allocate in runtime (or in c# array is dynamic?)
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9You should accept answers to your questions.SLaks– SLaks2010-11-19 17:05:58 +00:00Commented Nov 19, 2010 at 17:05
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1Here's how SO works. You ask questions, we answer them to the best of our ability. When you receive an answer that you like, upvote it by clicking the up arrow ^ next to that answer. One of the answers provided will be the best answer for your particular situation. You should "Accept" than answer by clicking the check mark next to that answer. When you upvote or accept answers, the answerer received "reputation points" for their effort, which is the currency that drives the site. You've asked many questions, but never accepted any answers. Please go back and accept the answersJohn Dibling– John Dibling2010-11-19 17:43:24 +00:00Commented Nov 19, 2010 at 17:43
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I'm not sure I understand what you are trying to ask here. Can you clarify?Bryan– Bryan2010-11-19 17:52:52 +00:00Commented Nov 19, 2010 at 17:52
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3 Answers
C# arrays are allocated at runtime on the heap.
C arrays are allocated at compile-time on the stack.
C can also allocate arrays at runtime using malloc. (Just remember to free them when you're done)
2 Comments
Grozz
"just remember" is a reason why many programming languages were invented ;)
Jasper
It should be noted that if
malloc has rather little place in C++. (It might be interesting if you really know what you're doing and you're doing micro-optimizations, otherwise) you should use new instead. And you should probably not use bare arrays either (unless you have a good reason). The fact that C++ is (mostly) a superset of C, means in C++ you can do anything you can in C, but you really shouldn't.In c++, you would need to do:
int* a = new int[n];
// Do stuff with the array
delete[] a;
Comments
but in c/c++ in wrong
int n; scanf("%d",&n); int a[n]
No! In C99 this code is correct because C99 supports Variable Length Arrays (VLA's).
In C++ the code is ill-formed because the array size must be a constant expression in C++ (although g++ supports VLA as an extension).
