If both strings are numbers, compare them as such

src/screens/media_library.cpp

@@ -98,7 +98,7 @@ bool MoveToAlbum(NC::Menu<AlbumEntry> &albums, const std::string &primary_tag, c
 struct SortSongs {
 	typedef NC::Menu<MPD::Song>::Item SongItem;
 	
-	static const std::array<MPD::Song::GetFunction, 3> GetFuns;
+	static const std::array<MPD::Song::GetFunction, 4> GetFuns;
 	
 	LocaleStringComparison m_cmp;
 
@@ -117,26 +117,16 @@ public:
 				return ret < 0;
 		}
 
-		// Sort by track numbers.
-		try {
-			ret = boost::lexical_cast<int>(a.getTags(&MPD::Song::getTrackNumber))
-			    - boost::lexical_cast<int>(b.getTags(&MPD::Song::getTrackNumber));
-		} catch (boost::bad_lexical_cast &) {
-			ret = a.getTrackNumber().compare(b.getTrackNumber());
-		}
-		if (ret != 0)
-			return ret < 0;
-
-		// If track numbers are equal, sort by the display format.
 		return Format::stringify<char>(Config.song_library_format, &a)
 		     < Format::stringify<char>(Config.song_library_format, &b);
 	}
 };
 
-const std::array<MPD::Song::GetFunction, 3> SortSongs::GetFuns = {{
+const std::array<MPD::Song::GetFunction, 4> SortSongs::GetFuns = {{
 	&MPD::Song::getDate,
 	&MPD::Song::getAlbum,
-	&MPD::Song::getDisc
+	&MPD::Song::getDisc,
+	&MPD::Song::getTrackNumber,
 }};
 
 class SortAlbumEntries {

src/utility/comparators.cpp

@@ -34,10 +34,22 @@ bool hasTheWord(const std::string &s)
 	&&     (s[3] == ' ');
 }
 
+long long strToLL(const char *s, size_t len)
+{
+	long long n = 0;
+	while (len--)
+		n = 10*n + *s++ - '0';
+	return n;
+}
+
 }
 
 int LocaleStringComparison::compare(const char *a, size_t a_len, const char *b, size_t b_len) const
 {
+	// If both strings are numbers, compare them as such.
+	if (std::all_of(a, a + a_len, isdigit) && std::all_of(b, b + b_len, isdigit))
+		return strToLL(a, a_len) - strToLL(b, b_len);
+
 	size_t ac_off = 0, bc_off = 0;
 	if (m_ignore_the)
 	{