CODEWITHSUNDEEP
c#
olidev
olidev

Reputation: 20684

Convert byte array to int

I am trying to do some conversion in C#, and I am not sure how to do this:

private int byteArray2Int(byte[] bytes)
{
    // bytes = new byte[] {0x01, 0x03, 0x04};

    // how to convert this byte array to an int?

    return BitConverter.ToInt32(bytes, 0); // is this correct? 
    // because if I have a bytes = new byte [] {0x32} => I got an exception
}

private string byteArray2String(byte[] bytes)
{
   return System.Text.ASCIIEncoding.ASCII.GetString(bytes);

   // but then I got a problem that if a byte is 0x00, it show 0x20
}

Could anyone give me some ideas?

Upvotes: 12

Views: 41144

Answers (4)

Ben Voigt
Ben Voigt

Reputation: 283931

BitConverter is the correct approach.

Your problem is because you only provided 8 bits when you promised 32. Try instead a valid 32-bit number in the array, such as new byte[] { 0x32, 0, 0, 0 }.

If you want an arbitrary length array converted, you can implement this yourself:

ulong ConvertLittleEndian(byte[] array)
{
    int pos = 0;
    ulong result = 0;
    foreach (byte by in array) {
        result |= ((ulong)by) << pos;
        pos += 8;
    }
    return result;
}

It's not clear what the second part of your question (involving strings) is supposed to produce, but I guess you want hex digits? BitConverter can help with that too, as described in an earlier question.

Upvotes: 28

Barak Rosenfeld
Barak Rosenfeld

Reputation: 337

byte[] bytes = { 0, 0, 0, 25 };

// If the system architecture is little-endian (that is, little end first), 
// reverse the byte array. 
if (BitConverter.IsLittleEndian)
  Array.Reverse(bytes);

int i = BitConverter.ToInt32(bytes, 0);
Console.WriteLine("int: {0}", i);

Upvotes: 4

JGU
JGU

Reputation: 909

A fast and simple way of doing this is just to copy the bytes to an integer using Buffer.BlockCopy:

UInt32[] pos = new UInt32[1];
byte[] stack = ...
Buffer.BlockCopy(stack, 0, pos, 0, 4);

This has the added benefit of being able to parse numerous integers into an array just by manipulating offsets..

Upvotes: 1

Mikant
Mikant

Reputation: 326

  1. this is correct, but you're missing, that Convert.ToInt32 'wants' 32 bits (32/8 = 4 bytes) of information to make a conversion, so you cannot convert just One byte: `new byte [] {0x32}

  2. absolutely the the same trouble you have. and do not forget about the encoding you use: from encoding to encoding you have 'different byte count per symbol'

Upvotes: 1

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