Different Byte values read in C++ and C#

Question

I've a program written in C++ to read binary files. And I'm writing the same program in C#. But in some cases C# is generating wrong byte.

C++ Code

ifstream s(argv[1], fstream::binary);
unsigned char b;
while(s.good())
{
     s >> b;
     //...
     //Some other code
}

C++ runs fine.

Equivalent C# Code

BinaryReader br = new BinaryReader(new FileStream("filename.bat", FileMode.Open));
byte b;
while(br.BaseStream.Position != br.BaseStream.Length && br.BaseStream.CanRead)
{
     b = br.ReadByte();
     //...
     // some other code
}

Some values of C# are not the same as C++ Please help thank you.