Using CRC32 to compare two files
Another way to calculate the has value is using Crc32. Unfortunately .Net
does not have an implemntation of this Algo. But the open source Zip utility
for .NET, SharpZipLib has this utility
. Here are the same files compared
using Crc32 using the Crc32 class from the
ICSharpCode.SharpZipLib.Checksums namespace.
1 Crc32 crc32 = new Crc32();
2 FileStream fileStream_1 =
3 new FileStream("Test.txt", FileMode.Open);
4 fileStream_1.Position = 0;
5 byte[] buffer = GetBuffer(fileStream_1);
6 crc32.Update(buffer);
7 long hashValue_1 = crc32.Value;
8 Console.Out.WriteLine("crc32 = {0}", crc32.Value);
9 fileStream_1.Close();
10
11 crc32.Reset();
12
13 FileStream fileStream_2 =
14 new FileStream("Copy of Test.txt", FileMode.Open);
15 fileStream_2.Position = 0;
16 buffer = GetBuffer(fileStream_2);
17 crc32.Update(buffer);
18 long hashValue_2 = crc32.Value;
19 Console.Out.WriteLine("crc32 = {0}", crc32.Value);
20 fileStream_2.Close();
21
22 Console.Out.WriteLine("hashValue_2.Equals(hashValue_1 = {0}",
23 hashValue_2.Equals(hashValue_1));
24 Console.Read();
where GetBuffer() is
1 private static byte[] GetBuffer(Stream stream)
2 {
3 byte[] buffer = new byte[(int)stream.Length];
4 stream.Read(buffer, 0, buffer.Length);
5 return buffer;
6 }
The output is 
Hope this helps someone
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