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Improve accuracy of numeric to float 

fixes #27
non-blocking
Jack Christensen 2020-05-13 08:05:19 -05:00
parent 6a1a9d05bc
commit 238967ec4e
2 changed files with 8 additions and 10 deletions
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17
numeric.go
View File

@ -291,19 +291,16 @@ func (dst *Numeric) toBigInt() (*big.Int, error) {
}
func (src *Numeric) toFloat64() (float64, error) {
f, err := strconv.ParseFloat(src.Int.String(), 64)
buf := make([]byte, 0, 32)
buf = append(buf, src.Int.String()...)
buf = append(buf, 'e')
buf = append(buf, strconv.FormatInt(int64(src.Exp), 10)...)
f, err := strconv.ParseFloat(string(buf), 64)
if err != nil {
return 0, err
}
if src.Exp > 0 {
for i := 0; i < int(src.Exp); i++ {
f *= 10
}
} else if src.Exp < 0 {
for i := 0; i > int(src.Exp); i-- {
f /= 10
}
}
return f, nil
}

1
numeric_test.go
View File

@ -266,6 +266,7 @@ func TestNumericAssignTo(t *testing.T) {
{src: &pgtype.Numeric{Int: big.NewInt(42), Status: pgtype.Present}, dst: &_i8, expected: _int8(42)},
{src: &pgtype.Numeric{Int: big.NewInt(0), Status: pgtype.Null}, dst: &pi8, expected: ((*int8)(nil))},
{src: &pgtype.Numeric{Int: big.NewInt(0), Status: pgtype.Null}, dst: &_pi8, expected: ((*_int8)(nil))},
{src: &pgtype.Numeric{Int: big.NewInt(1006), Exp: -2, Status: pgtype.Present}, dst: &f64, expected: float64(10.06)}, // https://github.com/jackc/pgtype/issues/27
}
for i, tt := range simpleTests {