some programmers use CRC to check if their programs is patch or modified by crackers. I just wonder how could they do that. i do read some articles about CRC, and and i could do is make an app to check the CRC of an other app, but i'm unable to make an app to check for it own integrity. I hope my question is clear enought.
All i want to do is to check for my app, if 1 byte is changed then exit the app.

Thanks guys.