fix double->string->double round-trip (bump minor ver.)

See open-source-parsers#98.
  http://stackoverflow.com/questions/747470/what-is-the-meaning-of-numeric-limitsdoubledigits10/16941784#16941784

Author: cdunn2001

src/lib_json/json_writer.cpp

@@ -87,13 +87,13 @@ std::string valueToString(double value) {
                                                       // visual studio 2005 to
                                                       // avoid warning.
 #if defined(WINCE)
-  len = _snprintf(buffer, sizeof(buffer), "%.16g", value);
+  len = _snprintf(buffer, sizeof(buffer), "%.17g", value);
 #else
-  len = sprintf_s(buffer, sizeof(buffer), "%.16g", value);
+  len = sprintf_s(buffer, sizeof(buffer), "%.17g", value);
 #endif
 #else
   if (isfinite(value)) {
-    len = snprintf(buffer, sizeof(buffer), "%.16g", value);
+    len = snprintf(buffer, sizeof(buffer), "%.17g", value);
   } else {
     // IEEE standard states that NaN values will not compare to themselves
     if (value != value) {

src/test_lib_json/main.cpp

@@ -926,7 +926,7 @@ JSONTEST_FIXTURE(ValueTest, integers) {
   JSONTEST_ASSERT_EQUAL(float(uint64ToDouble(Json::UInt64(1) << 63)),
                         val.asFloat());
   JSONTEST_ASSERT_EQUAL(true, val.asBool());
-  JSONTEST_ASSERT_STRING_EQUAL("9.223372036854776e+18",
+  JSONTEST_ASSERT_STRING_EQUAL("9.2233720368547758e+18",
                                normalizeFloatingPointStr(val.asString()));
 
   // int64 min
@@ -974,7 +974,7 @@ JSONTEST_FIXTURE(ValueTest, integers) {
   JSONTEST_ASSERT_EQUAL(-9223372036854775808.0, val.asDouble());
   JSONTEST_ASSERT_EQUAL(-9223372036854775808.0, val.asFloat());
   JSONTEST_ASSERT_EQUAL(true, val.asBool());
-  JSONTEST_ASSERT_STRING_EQUAL("-9.223372036854776e+18",
+  JSONTEST_ASSERT_STRING_EQUAL("-9.2233720368547758e+18",
                                normalizeFloatingPointStr(val.asString()));
 
   // 10^19
@@ -1065,7 +1065,7 @@ JSONTEST_FIXTURE(ValueTest, integers) {
   JSONTEST_ASSERT_EQUAL(18446744073709551616.0, val.asDouble());
   JSONTEST_ASSERT_EQUAL(18446744073709551616.0, val.asFloat());
   JSONTEST_ASSERT_EQUAL(true, val.asBool());
-  JSONTEST_ASSERT_STRING_EQUAL("1.844674407370955e+19",
+  JSONTEST_ASSERT_STRING_EQUAL("1.8446744073709552e+19",
                                normalizeFloatingPointStr(val.asString()));
 #endif
 }
@@ -1217,7 +1217,7 @@ JSONTEST_FIXTURE(ValueTest, nonIntegers) {
                         normalizeFloatingPointStr(val.asString()));
 
   val = Json::Value(1.2345678901234);
-  JSONTEST_ASSERT_STRING_EQUAL("1.2345678901234",
+  JSONTEST_ASSERT_STRING_EQUAL("1.2345678901234001",
                                normalizeFloatingPointStr(val.asString()));
 
   // A 16-digit floating point number.