math/big: fix several issues with string->Float conversion
Change-Id: I7bf7154e2d8d779fdf7f1d2bb561a06ad174f3b0
Reviewed-on: https://go-review.googlesource.com/4883
Reviewed-by: Alan Donovan <adonovan@google.com>
diff --git a/src/math/big/floatconv_test.go b/src/math/big/floatconv_test.go
index 4a91a63..e7920d0 100644
--- a/src/math/big/floatconv_test.go
+++ b/src/math/big/floatconv_test.go
@@ -15,6 +15,7 @@
s string
x float64
}{
+ // basics
{"0", 0},
{"-0", -0},
{"+0", 0},
@@ -28,34 +29,69 @@
{"1.", 1},
{"+1.", 1},
+ // various zeros
{"0e100", 0},
{"-0e+100", 0},
{"+0e-100", 0},
{"0E100", 0},
{"-0E+100", 0},
{"+0E-100", 0},
- {"0p100", 0},
- {"-0p+100", 0},
- {"+0p-100", 0},
+ // various decimal exponent formats
{"1.e10", 1e10},
{"1e+10", 1e10},
{"+1e-10", 1e-10},
{"1E10", 1e10},
{"1.E+10", 1e10},
{"+1E-10", 1e-10},
- {"1p10", 1 << 10},
- {"1p+10", 1 << 10},
- {"+1.p-10", 1.0 / (1 << 10)},
+ // misc decimal values
+ {"3.14159265", 3.14159265},
{"-687436.79457e-245", -687436.79457e-245},
{"-687436.79457E245", -687436.79457e245},
- {"1024.p-12", 0.25},
- {"-1.p10", -1024},
- {"0.25p2", 1},
-
{".0000000000000000000000000000000000000001", 1e-40},
{"+10000000000000000000000000000000000000000e-0", 1e40},
+
+ // decimal mantissa, binary exponent
+ {"0p0", 0},
+ {"-0p0", -0},
+ {"1p10", 1 << 10},
+ {"1p+10", 1 << 10},
+ {"+1p-10", 1.0 / (1 << 10)},
+ {"1024p-12", 0.25},
+ {"-1p10", -1024},
+ {"1.5p1", 3},
+
+ // binary mantissa, decimal exponent
+ {"0b0", 0},
+ {"-0b0", -0},
+ {"0b0e+10", 0},
+ {"-0b0e-10", -0},
+ {"0b1010", 10},
+ {"0B1010E2", 1000},
+ {"0b.1", 0.5},
+ {"0b.001", 0.125},
+ {"0b.001e3", 125},
+
+ // binary mantissa, binary exponent
+ {"0b0p+10", 0},
+ {"-0b0p-10", -0},
+ {"0b.1010p4", 10},
+ {"0b1p-1", 0.5},
+ {"0b001p-3", 0.125},
+ {"0b.001p3", 1},
+ {"0b0.01p2", 1},
+
+ // hexadecimal mantissa and exponent
+ {"0x0", 0},
+ {"-0x0", -0},
+ {"0x0p+10", 0},
+ {"-0x0p-10", -0},
+ {"0xff", 255},
+ {"0X.8p1", 1},
+ {"-0X0.00008p16", -0.5},
+ {"0x0.0000000000001p-1022", math.SmallestNonzeroFloat64},
+ {"0x1.fffffffffffffp1023", math.MaxFloat64},
} {
var x Float
x.SetPrec(53)
@@ -341,7 +377,11 @@
// and its output for 0.0 prints a biased exponent value
// as in 0p-1074 which makes no sense to emulate here)
if test.prec == 53 && test.format != 'p' && f.Sign() != 0 {
- f64, _ := f.Float64()
+ f64, acc := f.Float64()
+ if acc != Exact {
+ t.Errorf("%v: expected exact conversion to float64", test)
+ continue
+ }
got := strconv.FormatFloat(f64, test.format, test.digits, 64)
if got != test.want {
t.Errorf("%v: got %s; want %s", test, got, test.want)
