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allocating a 2D array
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Join Date: Nov 2008
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Junior Poster in Training
How can I allocate a 2D array? (on the heap) It needs to be dynamically allocated because the values of rows and columns aren't known.
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You can't use vectors?
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Originally Posted by Dave Sinkula 
You can't use vectors?
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Posting Whiz in Training
Make pointer to pointer
Then to each of that n pointers
After that you can use it as regular 2D array:
**ptr , and allocate n pointers to it.Then to each of that n pointers
*ptr[i] allocate n int's (or whatever).After that you can use it as regular 2D array:
ptr[i][j] 
It's not a problem to allocate 2D array or what else in C++. The problem is: how do you want access the allocated storage. You know that it's impossible to declare 2D array variable with run-time defined extents in C and C++.
The most straightforward approach in C style but with templates (w/o argument check):
More elaborated approaches: define your own class encapsulated all mechanics described above, use vector<vector< >> or valarray<valarray< >> templates. Search this forum: it was a very popular theme 1 or 2 month ago.
Search inet: there are lots of Matrix classes which implements 2D dynamic arrays logics.
The most straightforward approach in C style but with templates (w/o argument check):
C++ Syntax (Toggle Plain Text)
Search inet: there are lots of Matrix classes which implements 2D dynamic arrays logics.
Last edited by ArkM; Nov 8th, 2008 at 3:44 pm.
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