Using New

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Just been looking over Dynamic Memory Allocation, using new.

Heres a snippet of the code i've got.

c++ Syntax (Toggle Plain Text)
	vertices = new float *[v];
	for (i = 0; i < v; ++i)
	{
		vertices[i] = new float[3];
	}
	vertices = new float *[v];
	for (i = 0; i < v; ++i)
	{
		vertices[i] = new float[3];
	}

what i was thinking was could i just do

c++ Syntax (Toggle Plain Text)
vertices = new float[v][3];
vertices = new float[v][3];

instead of the for loop, are there any benefits for using either or are they exactly the same.

thanks in advance

finally one other minor question, currently all of my classes are in the same .cpp file as my main function, is there a way to put the classes into seperate .cpp files rather like java. i tried this initially but got errors about my code, and after moving them into the same file the program ran perfectly.

- Matt

Last edited by midimatt; May 15th, 2008 at 2:00 am.

midimatt

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May 15th, 2008

Re: Using New

Well if you declare the pointer the right way, then yes you can allocate the whole 2D array in one step.
float (*vertices)[3];
But this only works when all the minor dimensions are constants.

BTW - Use std::vector in C++.

Salem

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May 15th, 2008

Re: Using New

Click to Expand / Collapse Quote originally posted by midimatt ...

what i was thinking was could i just do
c++ Syntax (Toggle Plain Text)
vertices = new float[v][3];
vertices = new float[v][3];

this one only works if the "3" part is a constant, and always creates a "rectangular" array made of contiguous parts, no pointers involved

bugmenot

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