Get FILE extension from a file or path

Question

I'm trying to create a method that can get the extension of a file. I found multiple alternatives and this one was my solution:

const char *getExt(const char *filename) {
    const char *ext = strrchr(filename, '.');
    if(!ext || ext == filename){
        return "No Extension";
    }else{
        return ext + 1;
    }
}

Now, the problem is with the extension .tar.gz.

How can I select this kind of extension too without messing every other extension with only one dot (.)?

file extensions are only a *convention* (at least on Linux). You could have several ones. — Basile Starynkevitch, Mar 02 '18 at 17:39
Find the *first* `'.'` instead of the last? Since "extension" is just a convention, even on Windows these days, there are no real rules that specify what it is. If you had e.g. `file.name.with.many.dots`, what would the "extension" be? — Some programmer dude, Mar 02 '18 at 17:39
Duplicate: https://stackoverflow.com/questions/5309471/getting-file-extension-in-c — c0utinh0, Mar 02 '18 at 17:42
You need to make a definition. What is the "file extension" of a file named "my.great.photo.jpg"? — William Pursell, Mar 02 '18 at 18:22

score 0 · Answer 1 · answered Mar 02 '18 at 17:52

In use by me for many years:

char *GetExtension (const char *str)                // Extract the extension from the string  (incl '.')
{
    const char *pstr;
    if (!str ||!*str) return((char *)str);

    pstr = str + strlen(str) - 1;
    while ((*pstr != '/') && (*pstr != '\\') && (*pstr != '.') && (pstr > str))
            pstr--;
    if (*pstr != '.') return (0);
    return ((char *)pstr); //includes separator
}

Get FILE extension from a file or path

1 Answers1