file checksum example

讀取指定檔案計算該檔案之CheckSum。
程式碼 

using System;
using System.IO;
using System.Collections;

namespace ConsoleApplication1
{
public class CheckSum
{
private long sum = 0;

public CheckSum()
{
}

public void Add(int i)
{
sum += i;
}

public void Add(byte b)
{
sum += b;
}

public long GetCheckSum()
{
return sum;
}
}

public class MyClass
{
public static void Main()
{
string filename;
FileStream fs = null;
CheckSum sum = new CheckSum();

//Open the stream and read it back.
Console.Write("Please input filename:");
filename = Console.ReadLine();
Console.WriteLine("Trying to read {0}", filename);

if (File.Exists(filename))
Console.WriteLine("{0} is existed.", filename);

try
{
fs = File.Open(filename, FileMode.Open, FileAccess.Read);

if (fs.CanRead)
{
int value = 0;

while ((value = fs.ReadByte()) >= 0)
{
sum.Add(value);
}

Console.WriteLine("Checksum = {0,8:x}", sum.GetCheckSum());
}
else
Console.WriteLine("Cannot be read");
}
catch (Exception ex)
{
Console.WriteLine(ex.Message);
}
finally
{
fs.Close();
}

RL();
}

#region Helper methods
private static void RL()
{
Console.ReadLine();
}
#endregion
} 

}