Point V[rows];
Is this allowed in C++? rows is a variable whose value is given at runtime and Point is my class.
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strictly speaking, this would be a compile time error, not a run-time error.SingleNegationElimination– SingleNegationElimination2010-12-06 07:08:04 +00:00Commented Dec 6, 2010 at 7:08
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2 Answers
In C++ the comparable idiom is:
std::vector<Point> V(rows);
It's not 100% identical, because it still calls new Point[] (c99 can use the stack), but it still gives you the vector without performing multiple allocs.
answered Dec 6, 2010 at 5:53
SingleNegationElimination
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Only in C99 - it's a new feature called "variable length arrays". Normally, no.
I would strongly recommend against using this feature. If you have to do it, either use alloca, or allocate them properly, i.e. Point *V = new Point V[rows];.
BTW: Many people discourage Alloca as well. See here.
7 Comments
abbas
but then can i acces it as V[i] or not ?
EboMike
Yes. A pointer works essentially like an array. You just have to delete the array when you're done.
EboMike
Eh,
Point *V = new Point[rows];, obviously.EboMike
Glad to help! By the way, if you accept this answer, we both get rep points. Good luck with your program!
abbas
Thanks I just did that...i was tring it before thanking u but it said ur suppose to wait
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