类型为“ System.FormatException”的未处理异常

Question

I'm having a simple method inside my button. The logic behind is simple but i cant understand why I'm getting this error on the String set.

Here is the error

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

Additional information: Too many bytes in what should have been a 7 bit encoded Int32.

Here is the code

   private void button1_Click(object sender, EventArgs e)
    {
        FileStream data= new FileStream("data.DAT", FileMode.OpenOrCreate);
        BinaryReader a = new BinaryReader(data);
        while (data.Position < data.Length)
        {
            string name = a.ReadString();
            string egn = a.ReadString();
            string lenght = a.ReadString();
            int hour = a.ReadInt32();
            double price = a.ReadDouble();
            int days = a.ReadInt32();
            double result = price* hour* days;
            dataGridView1.Rows.Add(name, egn, lenght, hour, price, days, result);
        }
        data.Close();
    }

Answer 1

Without seeing the exact data it is hard to say, but I suspect you are misusing BinaryReader. For example, the ReadString method assumes the string to read is prefixed with the length in a specific format.

https://msdn.microsoft.com/en-us/library/system.io.binaryreader.readstring(v=vs.110).aspx

Basically, BinaryReader is designed to read from a file produced by BinaryWriter, not some arbitrary binary file.