Renaming file extensions (windows xp Home Edition (SP1))

[luvztoread]

I've just noticed that when I rename a photo or image, a message comes up and says "If you change a file name extension the file may become unusable. Are you sure you want to change it?" I can rename folders, but not the contents. How did this hapeen and how do I resolve it?
Thanks!

[viking33]

Don't try to resolve it.

Folders don't usually have file extensions but FILES do!
When you change an extension from. say .exe to ex_, it is no longer an executable file that will be recognized by your operating system. Same with com, dll, ini. Your system is looking for a particular file extension.

Changing a folder name may make your installation not find a desired group of files but it can be redirected to that new folder location.

[JohnGray]

What extensions were you renaming from, and renaming to?

Some graphics programs work out the graphic file format of a file from its extension, rather than by data clues at the front of the file. For example, even though a .GIF file will usually start with "GIF89a" and a .JPG will have "JFIF" six bytes in, that may well be the subject of a secondary test...

John

[StuartR]

If you set the check box in Windows Explorer, Tools > Folder Options > View > Hide Extensions for known file types then the extension parts of file names won't be visible and you can rename files without ever getting this error.

Many people prefer to clear this check box, so they can see file types and change them. If you do this then you must be careful not to accidentally change the file extension (the letters after the final dot in the filename) when you rename a file.

StuartR

[luvztoread]

Ok, here's the deal. "Hide extensions for known file types" was UNCHECKED when I was unable to rename files. When I checked the box, I can now rename my files. Isn't it supposed to work in the reverse???

[StuartR]

That is the correct way round. If the extensions are hidden then you can rename files wthout problems. If the extensions are not hidden then you need to be careful.

StuartR