Converting BYTE array to INT

Question

I have this kind of code

static void Main(string[] args)
{
     byte[] array = new byte[2] { 0x00, 0x1f };
     Console.WriteLine(BitConverter.ToInt32(array, 0));
}

However it does not work. It throws an exception:

Destination array is not long enough to copy all the items in the collection. Check array index and length.

What is wrong?

Answer 1

As the name suggests, an Int32 is 32 bits, or 4 bytes, so if you want to convert a byte array to an Int32, it needs to have a length of at least 4, (or more precisely, it needs to have least 4 bytes after the start position).

If all you have is two bytes, maybe you meant to use ToInt16?

Answer 2

An Int32 is composed of 4 bytes but the array only has 2. One way to work around this is to first convert to Int16 and then to Int32

Console.WriteLine((Int32)(BitConverter.ToInt16(array, 0)));

Note that in this specific usage converting to Int32 from Int16 doesn't change anything because the numbers print the same.

Answer 3

The documentation on BitConverter.ToInt32 says:

The ToInt32 method converts the bytes from index startIndex to startIndex + 3 to an Int32 value.

You need to specify at least 4 bytes, but you only have 2.