basename

/*
 *  call-seq:
 *     File.basename(file_name [, suffix] ) -> base_name
 *
 *  Returns the last component of the filename given in <i>file_name</i>,
 *  which must be formed using forward slashes (``<code>/</code>'')
 *  regardless of the separator used on the local file system. If
 *  <i>suffix</i> is given and present at the end of <i>file_name</i>,
 *  it is removed.
 *
 *     File.basename("/home/gumby/work/ruby.rb")          #=> "ruby.rb"
 *     File.basename("/home/gumby/work/ruby.rb", ".rb")   #=> "ruby"
 */

static VALUE
rb_file_s_basename(argc, argv)
    int argc;
    VALUE *argv;
{
    VALUE fname, fext, basename;
    const char *name, *p;
    long f, n;

    if (rb_scan_args(argc, argv, "11", &fname, &fext) == 2) {
        StringValue(fext);
    }
    StringValue(fname);
    if (RSTRING_LEN(fname) == 0 || !*(name = RSTRING_PTR(fname)))
        return fname;

    p = ruby_find_basename(name, &f, &n);
    if (n >= 0) {
        if (NIL_P(fext) || !(f = rmext(p, n, StringValueCStr(fext)))) {
            f = n;
        }
        if (f == RSTRING_LEN(fname)) return fname;
    }

    basename = rb_str_new(p, f);
    OBJ_INFECT(basename, fname);
    return basename;
}