CODEWITHSUNDEEP
c#arraystype-conversion
user1317200
user1317200

Reputation: 385

Converting BYTE array to INT

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?

Upvotes: 22

Views: 55013

Answers (4)

Robert Hegner
Robert Hegner

Reputation: 9396

This is an old question, but for .NET Core / .NET Standard > 2.1 there is new solution:

The System.Buffers.Binary.BinaryPrimitives class provides two static methods ReadInt32BigEndian and ReadInt32LittleEndian for this purpose.

Using this these methods has two advantages:

  1. It lets you explicitly specify if your number is stored as little endian or big endian.
  2. They accept a Span<T> which can be a performance advantage, depending on the scenario.

Upvotes: 7

p.s.w.g
p.s.w.g

Reputation: 149088

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?

Upvotes: 23

JaredPar
JaredPar

Reputation: 755577

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.

Upvotes: 12

Grant Winney
Grant Winney

Reputation: 66501

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.

Upvotes: 4

Related Questions