使用C＃进行十六进制值查找

Question

I'm trying to search for an hex value inside a file, if that value is present I need to copy 16 bytes of char from that found position. I'm trying to do the same in C#.

Please find my tried code below, correction will be greatly appreciated.

BinaryReader bw = new BinaryReader(File.OpenRead(filepath));
byte[] bc = { 0xa0, 0x00, 0x00, 0x03 };
for (int i = 0; i < br.BaseStream.Length-10;i++)
{

if (bw.ReadUInt32() == 0xa00003)
{
    Console.WriteLine("Found @ {0}", i);

}

bw.Close();

I"m getting an error as follows:

An unhandled exception of type 'System.IO.EndOfStreamException' occurred in mscorlib.dll

Additional information: Unable to read beyond the end of the stream.

Answer 1

The error is caused by the fact that your for loop has step equal to 1 and you are reading 4 bytes at a time. After reading, the Stream position is advanced by 4. Change your for loop to the following one:

for (int i = 0; i < br.BaseStream.Length - 10; i += 4)
{
    //...
}

EDIT:

If you want to search at every position without skipping 4 bytes every time, use the following code:

    Stream f = File.OpenRead(fileName);
    BinaryReader br = new BinaryReader(f);
    for (int i = 0; i < f.Length - 10; i++)
    {
        f.Seek(i, SeekOrigin.Begin);
        if (br.ReadUInt32() == 0xa00003)
        {
            Console.WriteLine("Found @ {0}", i);
        }
    }
    br.Close();