class person to binary file

Unfortunately C# doesn't support the reading and writing of random access files as such.

It is possible to do this with VB.NET because of stuff that was put into its runtime library for compatibility with VB6 (see   http://msdn.microsoft.com/en-us/library/aa903375(v=vs.71).aspx) but it would be difficult to get this to work from C#.

Probably the easiest way to read the file from C# would be to use a BinaryReader and its ReadChars method to read each of the 20 columns from each record in turn, depending on the length of that columm.

Unfortunately, you can't use the BinaryReader's ReadString method because this depends on the string being prefixed with its length which it won't be in a random access file.

As far as writing to the file is concerned you could use a BinaryWriter but would still have the same problem with length prefixed strings and would therefore have to use Write(char[]) rather than Write(string).

For updating an existing record, you could use the Seek method to set the pointer to the start (as a byte offset) of the appropriate record.

To read the whole file into a DataGridView, I'd create a Person object for each of the 1000 rows in the file, adding them to a List as you go.

You can then bind this list to the DataGridview and, if you like, autogenerate the columns from the properties of the Person class.

If you don't yet have a random access file, you could write the records to a CSV file instead.

Alternatively, you could binary serialize the whole List of Persons to a file and (at a later date) deserialize them back again. 

Of course, random access from the file itself would not be possible with these approaches.

Random access would be possible, though not particularly easy, if you used XML rather than binary serialization. You'd need to write some custom methods to retrieve, add, update or delete records.