checksum

[EmperorNero]

can someone explain to me what that is and its purpose?

from what I've gathered, a checksum is a very accurate file size number that you can use to compare different files.

and what are some good programs that can display a file's or program's checksum?

 

[Moonbeam]

The most I know is like this example ie that it's in like an ethernet packet (frame) and is a count of the bytes of data being sent and is used on the other end to see if that many bits came through. Acourse I don't know much.

 

[kranky]

I'm getting a little concerned about the number of tech questions being posted in OT and I resolved not to answer any, after this one.

A checksum is a number computed by adding up the value of bytes in something - a file, a frame (like Moonbeam said), whatever. Since the number would get large very quickly, any overflow is discarded. It's not based on the size of the file, it's based on the contents. It can be used to help make sure that two files are the same. For example, if one byte changes in a file, the checksum will change. But two bytes could be changed in such a way (for example, reversed in the file) that the checksum won't be affected. It's not foolproof, but it will probably detect changes due to transmission errors.

Since a basic checksum is calculated just by adding up the byte values in a file, it's a good exercise for a beginning programmer.

You could find some at download.com.