Comparing two byte arrays in .NET
How can I do this fast?
Sure I can do this:
static bool ByteArrayCompare(byte[] a1, byte[] a2)
{
if (a1.Length != a2.Length)
return false;
for (int i=0; i<a1.Length; i++)
if (a1[i]!=a2[i])
return false;
return true;
}
But I'm looking for either a BCL function or some highly optimized proven way to do this.
java.util.Arrays.equals((sbyte[])(Array)a1, (sbyte[])(Array)a2);
works nicely, but it doesn't look like that would work for x64.
Note my super-fast answer here.
You can use Enumerable.SequenceEqual method.
using System;
using System.Linq;
...
var a1 = new int[] { 1, 2, 3};
var a2 = new int[] { 1, 2, 3};
var a3 = new int[] { 1, 2, 4};
var x = a1.SequenceEqual(a2); // true
var y = a1.SequenceEqual(a3); // false
If you can't use .NET 3.5 for some reason, your method is OK.
Compilerrun-time environment will optimize your loop so you don't need to worry about performance.
P / Invoke权力激活!
[DllImport("msvcrt.dll", CallingConvention=CallingConvention.Cdecl)]
static extern int memcmp(byte[] b1, byte[] b2, long count);
static bool ByteArrayCompare(byte[] b1, byte[] b2)
{
// Validate buffers are the same length.
// This also ensures that the count does not exceed the length of either buffer.
return b1.Length == b2.Length && memcmp(b1, b2, b1.Length) == 0;
}
.NET 4中有一个新的内置解决方案 - IStructuralEquatable
static bool ByteArrayCompare(byte[] a1, byte[] a2)
{
return StructuralComparisons.StructuralEqualityComparer.Equals(a1, a2);
}
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