Golang Config.FloatFormat方法代码示例

func (i BigInt) Sprint(conf *config.Config) string {
	bitLen := i.BitLen()
	format := conf.Format()
	var maxBits = (uint64(conf.MaxDigits()) * 33222) / 10000 // log 10 / log 2 is 3.32192809489
	if uint64(bitLen) > maxBits && maxBits != 0 {
		// Print in floating point.
		return BigFloat{newF(conf).SetInt(i.Int)}.Sprint(conf)
	}
	if format != "" {
		verb, prec, ok := conf.FloatFormat()
		if ok {
			return i.floatString(verb, prec)
		}
		return fmt.Sprintf(format, i.Int)
	}
	// Is this from a rational and we could use an int?
	if i.BitLen() < intBits {
		return Int(i.Int64()).Sprint(conf)
	}
	switch conf.OutputBase() {
	case 0, 10:
		return fmt.Sprintf("%d", i.Int)
	case 2:
		return fmt.Sprintf("%b", i.Int)
	case 8:
		return fmt.Sprintf("%o", i.Int)
	case 16:
		return fmt.Sprintf("%x", i.Int)
	}
	Errorf("can't print number in base %d (yet)", conf.OutputBase())
	return ""
}

func (r BigRat) Sprint(conf *config.Config) string {
	format := conf.Format()
	if format != "" {
		verb, prec, ok := conf.FloatFormat()
		if ok {
			return r.floatString(verb, prec)
		}
		return fmt.Sprintf(conf.RatFormat(), r.Num(), r.Denom())
	}
	num := BigInt{r.Num()}
	den := BigInt{r.Denom()}
	return fmt.Sprintf("%s/%s", num.Sprint(conf), den.Sprint(conf))
}

func (i Int) Sprint(conf *config.Config) string {
	format := conf.Format()
	if format != "" {
		verb, prec, ok := conf.FloatFormat()
		if ok {
			return i.floatString(verb, prec)
		}
		return fmt.Sprintf(format, int64(i))
	}
	base := conf.OutputBase()
	if base == 0 {
		base = 10
	}
	return strconv.FormatInt(int64(i), base)
}

func (f BigFloat) Sprint(conf *config.Config) string {
	var mant big.Float
	exp := f.Float.MantExp(&mant)
	positive := 1
	if exp < 0 {
		positive = 0
		exp = -exp
	}
	verb, prec := byte('g'), 12
	format := conf.Format()
	if format != "" {
		v, p, ok := conf.FloatFormat()
		if ok {
			verb, prec = v, p
		}
	}
	// Printing huge floats can be very slow using
	// big.Float's native methods; see issue #11068.
	// For example 1e5000000 takes a minute of CPU time just
	// to print. The code below is instantaneous, by rescaling
	// first. It is however less feature-complete.
	// (Big ints are problematic too, but if you print 1e50000000
	// as an integer you probably won't be surprised it's slow.)

	if fastFloatPrint && exp > 10000 {
		// We always use %g to print the fraction, and it will
		// never have an exponent, but if the format is %E we
		// need to use a capital E.
		eChar := 'e'
		if verb == 'E' || verb == 'G' {
			eChar = 'E'
		}
		fexp := newF(conf).SetInt64(int64(exp))
		fexp.Mul(fexp, floatLog2)
		fexp.Quo(fexp, floatLog10)
		// We now have a floating-point base 10 exponent.
		// Break into the integer part and the fractional part.
		// The integer part is what we will show.
		// The 10**(fractional part) will be multiplied back in.
		iexp, _ := fexp.Int(nil)
		fraction := fexp.Sub(fexp, newF(conf).SetInt(iexp))
		// Now compute 10**(fractional part).
		// Fraction is in base 10. Move it to base e.
		fraction.Mul(fraction, floatLog10)
		scale := exponential(conf, fraction)
		if positive > 0 {
			mant.Mul(&mant, scale)
		} else {
			mant.Quo(&mant, scale)
		}
		ten := newF(conf).SetInt64(10)
		i64exp := iexp.Int64()
		// For numbers not too far from one, print without the E notation.
		// Shouldn't happen (exp must be large to get here) but just
		// in case, we keep this around.
		if -4 <= i64exp && i64exp <= 11 {
			if i64exp > 0 {
				for i := 0; i < int(i64exp); i++ {
					mant.Mul(&mant, ten)
				}
			} else {
				for i := 0; i < int(-i64exp); i++ {
					mant.Quo(&mant, ten)
				}
			}
			return fmt.Sprintf("%g\n", &mant)
		} else {
			sign := ""
			if mant.Sign() < 0 {
				sign = "-"
				mant.Neg(&mant)
			}
			// If it has a leading zero, rescale.
			digits := mant.Text('g', prec)
			for digits[0] == '0' {
				mant.Mul(&mant, ten)
				if positive > 0 {
					i64exp--
				} else {
					i64exp++
				}
				digits = mant.Text('g', prec)
			}
			return fmt.Sprintf("%s%s%c%c%d", sign, digits, eChar, "-+"[positive], i64exp)
		}
	}
	return f.Float.Text(verb, prec)
}