Slight improvement of Natural::compare, for instance: t1.txt now comes after t.txt

src/utility.cpp

@@ -316,6 +316,10 @@ int Natural::compare(const std::string &s1, const std::string &s2) {
   size_t i1 = 0;
   size_t i2 = 0;
   while(i1 < s1.size() && i2 < s2.size()) {
+    if(s1[i1] == '.' && s2[i2] != '.')
+      return -1;
+    if(s1[i1] != '.' && s2[i2] == '.')
+      return 1;
     if(is_digit(s1[i1]) && !is_digit(s2[i2]))
       return -1;
     if(!is_digit(s1[i1]) && is_digit(s2[i2]))

tests/utility_test.cpp

@@ -198,4 +198,10 @@ int main() {
     g_assert(Natural::compare("z2", "z11") == -1);
     g_assert(Natural::compare("z11", "z2") == 1);
   }
+  {
+    g_assert(Natural::compare("t", "t1") == -1);
+    g_assert(Natural::compare("t.txt", "t1.txt") == -1);
+    g_assert(Natural::compare("t1", "t") == 1);
+    g_assert(Natural::compare("t1.txt", "t.txt") == 1);
+  }
 }