.net FileStream拷贝大文件

string source = @"e:\1.pdf";
string target=@"e:\2.pdf";
FileStream fsread = new FileStream(source, FileMode.Open, FileAccess.Read);
FileStream fswrite = new FileStream(target, FileMode.Create, FileAccess.Write);
byte[] bytes=new byte[1024*5];
int r = fsread.Read(bytes, 0, bytes.Length);
while (r > 0)
{
    fswrite.Write(bytes, 0, r);
    double d = (fswrite.Position / (double)fsread.Length)*100;
    //显示进度时取2位小数
    Console.WriteLine("{0:F2}%",d);
    r = fsread.Read(bytes, 0, bytes.Length);
}
fswrite.Dispose();
fsread.Dispose();
Console.WriteLine("ok");