Don't emit decimal point if there are no trailing digits (#1210)

fmtlib · Jun 30, 2019 · ab0ba8a · ab0ba8a
1 parent bd3fd3b
commit ab0ba8a
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Showing 2 changed files with 6 additions and 3 deletions.
diff --git a/include/fmt/format.h b/include/fmt/format.h
@@ -1096,14 +1096,16 @@ It grisu_prettify(const char* digits, int size, int exp, It it,
   } else {
     // 1234e-6 -> 0.001234
     *it++ = static_cast<Char>('0');
-    *it++ = static_cast<Char>('.');
     int num_zeros = -full_exp;
     if (params.num_digits >= 0 && params.num_digits < num_zeros)
       num_zeros = params.num_digits;
-    it = std::fill_n(it, num_zeros, static_cast<Char>('0'));
     if (!params.trailing_zeros)
       while (size > 0 && digits[size - 1] == '0') --size;
-    it = copy_str<Char>(digits, digits + size, it);
+    if (num_zeros != 0 || size != 0) {
+      *it++ = static_cast<Char>('.');
+      it = std::fill_n(it, num_zeros, static_cast<Char>('0'));
+      it = copy_str<Char>(digits, digits + size, it);
+    }
   }
   return it;
 }

diff --git a/test/format-test.cc b/test/format-test.cc
@@ -1453,6 +1453,7 @@ TEST(FormatterTest, FormatDouble) {
 
 TEST(FormatterTest, PrecisionRounding) {
   EXPECT_EQ("0", format("{:.0f}", 0.0));
+  EXPECT_EQ("0", format("{:.0f}", 0.01));
   EXPECT_EQ("0", format("{:.0f}", 0.1));
   EXPECT_EQ("0.000", format("{:.3f}", 0.00049));
   EXPECT_EQ("0.001", format("{:.3f}", 0.0005));