Arrays with very large Indices

This is a discussion on Arrays with very large Indices within the C++ Programming forums, part of the General Programming Boards category; I am working on a simulation program that requires a large amount of variables in an array, such as: int ...

  1. #1
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    Arrays with very large Indices

    I am working on a simulation program that requires a large amount of variables in an array, such as:

    int Testp = 64;
    int taustp = 4096;
    float *sigma = new float[(Testp+1)*(taustp+1)*sizeof(float)];

    and then when I assign sigma later, I get a Segmentation Fault. This only happens when my index reaches about 16,000. Do I need to declare my indices somehow as a Long?

  2. #2
    Cat without Hat CornedBee's Avatar
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    No idea about the segmentation fault, beyond that int definitiely suffices for 16000, but you new[] calculates the element size on its own - you're currently allocating sizeof(float) (usually 4) times the space you intended.

    Can you post the code that actually segfaults?
    All the buzzt!
    CornedBee

    "There is not now, nor has there ever been, nor will there ever be, any programming language in which it is the least bit difficult to write bad code."
    - Flon's Law

  3. #3
    and the hat of wrongness Salem's Avatar
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    Perhaps you're using some crappy old 16-bit DOS compiler which limits the amount of any single allocation to 64K.

  4. #4
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    >float *sigma = new float[(Testp+1)*(taustp+1)*sizeof(float)];
    You don't need sizeof(float) in there. Just:
    Code:
    float *sigma = new float[(Testp+1)*(taustp+1)];

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