Until not so Long ago, I've not even known that you could compress specific folders, files or even entire drives using windows' builtin compression. Simple way to do this is just go to properties and check "compress contents to save disk space" and you're all set.
Firstly heard of it I thought it was just like winzip compressing files to reduce size or combile all files in one zipped file. but it seems like it has different use case than that.
and what's most interesting is the file is compressed but file's hash output remained same(short experiment using 3rd party hash calculator). how can this be real? if input changes, hash output must change(except in case of collision which is pretty rare and is off topic). for example, let's say I compressed a file named MYDOCUMENT.pdf, and I can just keep it that way , putting it in usb drives or other newly installed PC and just use it as it is just normal file , without manually decompressing it and such?
when I checked the file size in properties , size didn't change even a byte, but only "size on disk" changed decreasinly. so it seems that file's data remains intact as is(same hash value probably proves this), but it just compresses and decompresses when reading it from OS side.
another question would be, there's another compress algorithm using command line prompt, by typing "compact.exe /compactos:always", what's the difference between the two?
windows is giving me headache these days :/
