When a program like Ccleaner cleans out the Temp folder it deletes the files. If you change the settings in Ccleaner to overwrite the file say with the NSA 7 pass secure file deletion then it permanently deletes the files. To my understanding it overwrites these files.
My question is simple, how do they do this? I mean I mainly program with C# so I know that you can delete files programmatically and I know you can overwrite the data inside the file programmatically but to my understanding they actually overwrite the file from the hard disk to where it's not there at all. So how are they able to overwrite it from the hard drive?
Thanks in advance for all answers given.