// QuadToString returns the string representation of a Quad number.
// It calls the C function QuadToString of the original decNumber package.
//
// This function uses exponential notation quite often.
// E.g. 0.0000001 returns "1E-7", which is often not what we want.
//
// It is better to use the method AppendQuad() or String(), which don't use exponential notation for a wider range.
// AppendQuad() and String() write a number without exp notation if it can be displayed with at most 34 digits, and an optional fractional point.
//
// The status field of a is not checked.
// If you need to check the status of a, you can call a.Error().
//
func (a Quad) QuadToString() string {
var (
retStr C.Ret_str
strSlice []byte // capacity must be exactly DecquadString
s string
)
retStr = C.mdq_QuadToString(a.val) // may use exponent notation
strSlice = pool.Get().([]byte)[:DecquadString]
defer pool.Put(strSlice)
for i := 0; i < int(retStr.length); i++ {
strSlice[i] = byte(retStr.s[i])
}
s = string(strSlice[:retStr.length])
return s
}
// AppendQuad appends string representation of Quad into byte slice.
// AppendQuad and String are best to display Quad, as exponent notation is used less often than with QuadToString.
//
// AppendQuad() writes a number without exp notation if it can be displayed with at most 34 digits, and an optional fractional point.
// Else, falls back on QuadToString(), which will use exponential notation.
//
// See also method String(), which calls AppendQuad internally.
//
// The status field of a is not checked.
// If you need to check the status of a, you can call a.Error().
//
func AppendQuad(dst []byte, a Quad) []byte {
var (
retStr C.Ret_str
strSlice []byte // length must be exactly DecquadString
ret C.Ret_BCD
d byte
skipLeadingZero bool = true
inf_nan uint32
exp int32
sign uint32
BCDslice []byte // length must be exactly DecquadPmax
buff [DecquadString]byte // enough for sign optional "0." 34 digits
)
// fill BCD array
ret = C.mdq_to_BCD(a.val) // sign will be 1 for negative and non-zero number, else, 0. If Inf or Nan, returns an error.
BCDslice = pool.Get().([]byte)[:DecquadPmax]
defer pool.Put(BCDslice)
for i := 0; i < DecquadPmax; i++ {
BCDslice[i] = byte(ret.BCD[i])
}
inf_nan = uint32(ret.inf_nan)
exp = int32(ret.exp)
sign = uint32(ret.sign)
// if Quad value is not in 34 digits range, or Inf or Nan, we want our function to output the number, or Infinity, or NaN. Falls back on QuadToString.
if exp > 0 || exp < -DecquadPmax || inf_nan != 0 {
retStr = C.mdq_QuadToString(a.val) // may use exponent notation
strSlice = pool.Get().([]byte)[:DecquadString]
defer pool.Put(strSlice)
for i := 0; i < int(retStr.length); i++ {
strSlice[i] = byte(retStr.s[i])
}
dst = append(dst, strSlice[:retStr.length]...) // write buff into destination and return
return dst
}
// write string. Here, the number is not Inf nor Nan.
i := 0
integralPartLength := len(BCDslice) + int(exp) // here, exp is [-DecquadPmax ... 0]
BCDintegralPart := BCDslice[:integralPartLength]
BCDfractionalPart := BCDslice[integralPartLength:]
for _, d = range BCDintegralPart { // ==== write integral part ====
if skipLeadingZero && d == 0 {
continue
} else {
skipLeadingZero = false
}
buff[i] = '0' + d
i++
}
if i == 0 { // write '0' if no digit written for integral part
buff[i] = '0'
i++
}
if sign != 0 {
dst = append(dst, '-') // write '-' sign if any into destination
}
dst = append(dst, buff[:i]...) // write integral part into destination
if exp == 0 { // if no fractional part, just return
return dst
}
dst = append(dst, '.') // ==== write fractional part ====
i = 0
for _, d = range BCDfractionalPart {
buff[i] = '0' + d
i++
}
dst = append(dst, buff[:i]...) // write fractional part into destination
return dst
}