[Qemu-devel] [PATCH v2 5/6] qapi: String visitor, use %f represenation for floats

[Michael Roth]

Currently string-output-visitor formats floats as %g, which is nice in
that trailing 0's are automatically truncated, but otherwise this causes
some issues:

 - it 6 uses significant figures instead of 6 decimal places, which
   means something like 155777.5 (which even has an exact floating point
   representation) will be rounded to 155778 when converted to a string.

 - output will be presented in scientific notation when the normalized
   form requires a 10^x multiplier. Not a huge deal, but arguably less
   readable for command-line arguments.

 - due to using sig figs instead of hard-defined decimal places, it
   fails a lot of the test-visitor-serialization unit tests for floats.

Instead, let's just use %f, which is what the QJSON and the QMP visitors
use.

Signed-off-by: Michael Roth <address@hidden>
---
 qapi/string-output-visitor.c |    2 +-
 test-string-output-visitor.c |    2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/qapi/string-output-visitor.c b/qapi/string-output-visitor.c
index 92b0305..34e525e 100644
--- a/qapi/string-output-visitor.c
+++ b/qapi/string-output-visitor.c
@@ -52,7 +52,7 @@ static void print_type_number(Visitor *v, double *obj, const 
char *name,
                               Error **errp)
 {
     StringOutputVisitor *sov = DO_UPCAST(StringOutputVisitor, visitor, v);
-    string_output_set(sov, g_strdup_printf("%g", *obj));
+    string_output_set(sov, g_strdup_printf("%f", *obj));
 }
 
 char *string_output_get_string(StringOutputVisitor *sov)
diff --git a/test-string-output-visitor.c b/test-string-output-visitor.c
index 22909b8..608f14a 100644
--- a/test-string-output-visitor.c
+++ b/test-string-output-visitor.c
@@ -84,7 +84,7 @@ static void test_visitor_out_number(TestOutputVisitorData 
*data,
 
     str = string_output_get_string(data->sov);
     g_assert(str != NULL);
-    g_assert_cmpstr(str, ==, "3.14");
+    g_assert_cmpstr(str, ==, "3.140000");
     g_free(str);
 }
 
-- 
1.7.4.1