How to convert integer to binary string in C#?

Question

I\'m writing a number converter. How can I convert a integer to a binary string in C# WITHOUT using built-in functions (Convert.ToString does different things b

Answer 1

Simple soution:

IntToBinValue = Convert.ToString(6, 2);

Answer 2

At least part of the answer is to use decimal.GetBits(someValue) to convert the decimal to its binary representation.

BitConverter.GetBytes can be used, in turn, on the elements returned from decimal.GetBits() to convert integers into bytes.

You may find the decimal.GetBits() documentation useful.

I'm not sure how to go from bytes to decimal, though.

Update: Based on Author's update:

BitConverter contains methods for converting numbers to bytes, which is convenient for getting the binary representation. The GetBytes() and ToInt32() methods are convenient for conversions in each direction. The ToString() overloads are convenient for creating a hexadecimal string representation if you would find that easier to interpret as 1's and 0's.

Answer 3

This is an unsafe implementation:

    private static unsafe byte[] GetDecimalBytes(decimal d)
    {
        byte* dp = (byte*) &d;
        byte[] result = new byte[sizeof(decimal)];
        for (int i = 0; i < sizeof(decimal); i++, dp++)
        {
            result[i] = *dp;
        }
        return result;
    }

And here is reverting back:

    private static unsafe decimal GetDecimal(Byte[] bytes)
    {
        if (bytes == null)
            throw new ArgumentNullException("bytes");

        if (bytes.Length != sizeof(decimal))
            throw new ArgumentOutOfRangeException("bytes", "length must be 16");

        decimal d = 0;
        byte* dp = (byte*)&d;
        byte[] result = new byte[sizeof(decimal)];
        for (int i = 0; i < sizeof(decimal); i++, dp++)
        {
            *dp = bytes[i];
        }
        return d;
    }

Answer 4

Here's mine: (The upper part convert 32-char binary string to 32-bit integer, the lower part convert 32-bit integer back to 32-char binary string). Hope this helps.

        string binaryString = "011100100111001001110011";
        int G = 0;

        for (int i = 0; i < binaryString.Length; i++)
            G += (int)((binaryString[binaryString.Length - (i + 1)] & 1) << (i % 32));

        Console.WriteLine(G); //‭7500403‬
        binaryString = string.Empty;

        for (int i = 31; i >= 0; i--)
        {
            binaryString += (char)(((G & (1 << (i % 32))) >> (i % 32)) | 48);
        }

        Console.WriteLine(binaryString); //00000000011100100111001001110011

Answer 5

You can construct the representations digit by digit from first principles.

Not sure what built-in functions you don't want to use, but presumably you can construct a string character by character?

1. Start with the highest power of two greater than the number.
2. Push a "1" into your string.
3. Subtract that power of two from your number.
4. Take the next-lowest power of two. If you've reached one-half, stop. You're done.
5. If the number that's left is greater than this power of two, go back to step 2. If not, push a "0" into the string and go back to step 4.

For one's complement and two's complement, calculate those with an additional step.

Or is this way too basic for what you need?

Answer 6

   var a = Convert.ToString(4, 2).PadLeft(8, '0');