C# byte array comparison

Question

I have two byte arrays in C# using .NET 3.0.

What is the "most efficient" way to compare whether the two byte arrays contains the same content for each element?

For example, byte array {0x1, 0x2} is the same as {0x1, 0x2}. But byte array {0x1, 0x2} and byte array {0x2, 0x1} are not the same.

Answer 1

Well, you could use:

public static bool ByteArraysEqual(byte[] b1, byte[] b2)
{
    if (b1 == b2) return true;
    if (b1 == null || b2 == null) return false;
    if (b1.Length != b2.Length) return false;
    for (int i=0; i < b1.Length; i++)
    {
        if (b1[i] != b2[i]) return false;
    }
    return true;
}

(I normally use braces for everything, but I thought I'd experiment with this layout style just for a change...)

This has a few optimisations which SequenceEqual can't (or doesn't) perform - such as the up-front length check. Direct array access will also be a bit more efficient than using the enumerator.

Admittedly it's unlikely to make a significant difference in most cases...

You could possibly make it faster in unmanaged code by making it compare 32 or 64 bits at a time instead of 8 - but I wouldn't like to code that on the fly.

Answer 2

You can use the SequenceEqual method:

bool areEqual = firstArray.SequenceEqual(secondArray);

As mentioned in the comments, SequenceEqual requires .NET 3.5 (or LINQBridge if you're using VS2008 and targeting an earlier version of the framework).