Converting Int32 to 24-bit signed integer

c# integer endianness bitconverter
drharris picture drharris · Feb 7, 2011 · Viewed 8.1k times · Source

I have a need to convert an Int32 value to a 3-byte (24-bit) integer. Endianness remains the same (little), but I cannot figure out how to move the sign appropriately. The values are already constrained to the proper range, I just can't figure out how to convert 4 bytes to 3. Using C# 4.0. This is for hardware integration, so I have to have 24-bit values, cannot use 32 bit.

Answer

Jeremiah Willcock picture Jeremiah Willcock · Feb 7, 2011

If you want to do that conversion, just remove the top byte of the four-byte number. Two's complement representation will take care of the sign correctly. If you want to keep the 24-bit number in an Int32 variable, you can use v & 0xFFFFFF to get just the lower 24 bits. I saw your comment about the byte array: if you have space in the array, write all four bytes of the number and just send the first three; that is specific to little-endian systems, though.

Related questions

C# Big-endian ulong from 4 bytes

Im trying to cast a 4 byte array to an ulong in C#. I'm currently using this code: atomSize = BitConverter.ToUInt32(buffer, 0); The byte[4] contains this: 0 0 0 32 However, the bytes are Big-Endian. Is there a simple way to convert this Big-Endian ulong …

Read More
How to sum up an array of integers in C#

Is there a better shorter way than iterating over the array? int[] arr = new int[] { 1, 2, 3 }; int sum = 0; for (int i = 0; i < arr.Length; i++) { sum += arr[i]; } clarification: Better primary means cleaner code but hints on performance improvement are …

Read More
What is the difference between an int and an Integer in Java and C#?

I was reading More Joel on Software when I came across Joel Spolsky saying something about a particular type of programmer knowing the difference between an int and an Integer in Java/C# (Object-Oriented Programming Languages). So, what is the …

Read More