Put digits into an own segment with the title #

Change-Id: I5f3ae179d388c417abd512974df22fd78a699354
diff --git a/android/PhonebookIndex.cpp b/android/PhonebookIndex.cpp
index 57f3bda..8f5e4be 100644
--- a/android/PhonebookIndex.cpp
+++ b/android/PhonebookIndex.cpp
@@ -143,8 +143,15 @@
 
   UChar c = out[0];
 
-  // We are only interested in letters
   if (!u_isalpha(c)) {
+    // Digits go into a # section. Everything else goes into the empty section
+    // The unicode function u_isdigit would also identify other characters as digits (arabic),
+    // but if we caught them here we'd risk having the same section before and after alpha-letters
+    // which might break the assumption that each section exists only once
+    if (c >= '0' && c <= '9') {
+      out[0] = '#';
+      return 1;
+    }
     return 0;
   }