How to decrease the length of an integer Array (with binary data [0,1]) without losing data???

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I have an integer array of length 900 that contains only binary data [0,1]. I want to short the length of the array without losing binary data formate(original array values).
Is it possible to short the length of array of 900 into 10 or 20 length in C#???

Posted 6-Feb-11 0:09am

mirfan00

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OriginalGriff · Accepted Answer · 2011-02-06T00:35:00

No.
There is no re-dimension facility in C#.
Instead, create a new array and use Array.Copy[^] to transfer the original values.

private T[] shrinkArray<T>(T[] oldArray, int newLength)
    {
    T[] newArray = new T[newLength];
    Array.Copy(oldArray, newArray, newLength);
    return newArray;
    }

"But it loses original data in array of 900 length. What you say now?"

Oops! Sorry - I missed that you were trying to pack the bits!

Try this: (untested)

C#

private static int[] PackBits(int[] inp)
    {
    int intsRequired = (inp.Length + 31) / 32;
    int[] outp = new int[intsRequired];
    int curOut = 0;
    for (int i = 0; i < inp.Length; i++)
        {
        outp[curOut] = (outp[curOut] << 1) | inp[i];
        if ((i % 32) == 31)
            {
            // output int complete
            curOut++;
            }
        }
    return outp;
    }

"Well, it works fine. Thanks :)
Now,my next question is how to unpack it (get original back)????"

Well, the Haynes Book of Lies always suggests that "reassembly is the reverse of disassembly".

I used to hate that! But it is true.

I have revised the PackBits so it is easier to unpack when the data doesn't fit exactly into a complete int:

C#

private static int[] PackBits(int[] inp)
    {
    int intsRequired = (inp.Length + 31) / 32;
    int[] outp = new int[intsRequired];
    int curOut = 0;
    for (int i = 0; i < inp.Length; i++)
        {
        outp[curOut] |= inp[i] << (i % 32);
        if ((i % 32) == 31)
            {
            // output int complete
            curOut++;
            }
        }
    return outp;
    }
private static int[] UnpackBits(int[] inp, int len)
    {
    int intsRequired = inp.Length * 32;
    int[] outp = new int[intsRequired];
    int curOut = 0;
    foreach (int val in inp)
        {
        uint x = (uint) val;
        for (int i = 0; i < 32; i++)
            {
            outp[curOut++] = (int) ((x >> i) & 1);
            }
        }
    return outp;
    }