...
Run Format

Source file src/strconv/ftoa_test.go

Documentation: strconv

  // Copyright 2009 The Go Authors. All rights reserved.
  // Use of this source code is governed by a BSD-style
  // license that can be found in the LICENSE file.
  
  package strconv_test
  
  import (
  	"math"
  	"math/rand"
  	. "strconv"
  	"testing"
  )
  
  type ftoaTest struct {
  	f    float64
  	fmt  byte
  	prec int
  	s    string
  }
  
  func fdiv(a, b float64) float64 { return a / b }
  
  const (
  	below1e23 = 99999999999999974834176
  	above1e23 = 100000000000000008388608
  )
  
  var ftoatests = []ftoaTest{
  	{1, 'e', 5, "1.00000e+00"},
  	{1, 'f', 5, "1.00000"},
  	{1, 'g', 5, "1"},
  	{1, 'g', -1, "1"},
  	{20, 'g', -1, "20"},
  	{1234567.8, 'g', -1, "1.2345678e+06"},
  	{200000, 'g', -1, "200000"},
  	{2000000, 'g', -1, "2e+06"},
  
  	// g conversion and zero suppression
  	{400, 'g', 2, "4e+02"},
  	{40, 'g', 2, "40"},
  	{4, 'g', 2, "4"},
  	{.4, 'g', 2, "0.4"},
  	{.04, 'g', 2, "0.04"},
  	{.004, 'g', 2, "0.004"},
  	{.0004, 'g', 2, "0.0004"},
  	{.00004, 'g', 2, "4e-05"},
  	{.000004, 'g', 2, "4e-06"},
  
  	{0, 'e', 5, "0.00000e+00"},
  	{0, 'f', 5, "0.00000"},
  	{0, 'g', 5, "0"},
  	{0, 'g', -1, "0"},
  
  	{-1, 'e', 5, "-1.00000e+00"},
  	{-1, 'f', 5, "-1.00000"},
  	{-1, 'g', 5, "-1"},
  	{-1, 'g', -1, "-1"},
  
  	{12, 'e', 5, "1.20000e+01"},
  	{12, 'f', 5, "12.00000"},
  	{12, 'g', 5, "12"},
  	{12, 'g', -1, "12"},
  
  	{123456700, 'e', 5, "1.23457e+08"},
  	{123456700, 'f', 5, "123456700.00000"},
  	{123456700, 'g', 5, "1.2346e+08"},
  	{123456700, 'g', -1, "1.234567e+08"},
  
  	{1.2345e6, 'e', 5, "1.23450e+06"},
  	{1.2345e6, 'f', 5, "1234500.00000"},
  	{1.2345e6, 'g', 5, "1.2345e+06"},
  
  	{1e23, 'e', 17, "9.99999999999999916e+22"},
  	{1e23, 'f', 17, "99999999999999991611392.00000000000000000"},
  	{1e23, 'g', 17, "9.9999999999999992e+22"},
  
  	{1e23, 'e', -1, "1e+23"},
  	{1e23, 'f', -1, "100000000000000000000000"},
  	{1e23, 'g', -1, "1e+23"},
  
  	{below1e23, 'e', 17, "9.99999999999999748e+22"},
  	{below1e23, 'f', 17, "99999999999999974834176.00000000000000000"},
  	{below1e23, 'g', 17, "9.9999999999999975e+22"},
  
  	{below1e23, 'e', -1, "9.999999999999997e+22"},
  	{below1e23, 'f', -1, "99999999999999970000000"},
  	{below1e23, 'g', -1, "9.999999999999997e+22"},
  
  	{above1e23, 'e', 17, "1.00000000000000008e+23"},
  	{above1e23, 'f', 17, "100000000000000008388608.00000000000000000"},
  	{above1e23, 'g', 17, "1.0000000000000001e+23"},
  
  	{above1e23, 'e', -1, "1.0000000000000001e+23"},
  	{above1e23, 'f', -1, "100000000000000010000000"},
  	{above1e23, 'g', -1, "1.0000000000000001e+23"},
  
  	{fdiv(5e-304, 1e20), 'g', -1, "5e-324"},   // avoid constant arithmetic
  	{fdiv(-5e-304, 1e20), 'g', -1, "-5e-324"}, // avoid constant arithmetic
  
  	{32, 'g', -1, "32"},
  	{32, 'g', 0, "3e+01"},
  
  	{100, 'x', -1, "%x"},
  
  	{math.NaN(), 'g', -1, "NaN"},
  	{-math.NaN(), 'g', -1, "NaN"},
  	{math.Inf(0), 'g', -1, "+Inf"},
  	{math.Inf(-1), 'g', -1, "-Inf"},
  	{-math.Inf(0), 'g', -1, "-Inf"},
  
  	{-1, 'b', -1, "-4503599627370496p-52"},
  
  	// fixed bugs
  	{0.9, 'f', 1, "0.9"},
  	{0.09, 'f', 1, "0.1"},
  	{0.0999, 'f', 1, "0.1"},
  	{0.05, 'f', 1, "0.1"},
  	{0.05, 'f', 0, "0"},
  	{0.5, 'f', 1, "0.5"},
  	{0.5, 'f', 0, "0"},
  	{1.5, 'f', 0, "2"},
  
  	// http://www.exploringbinary.com/java-hangs-when-converting-2-2250738585072012e-308/
  	{2.2250738585072012e-308, 'g', -1, "2.2250738585072014e-308"},
  	// http://www.exploringbinary.com/php-hangs-on-numeric-value-2-2250738585072011e-308/
  	{2.2250738585072011e-308, 'g', -1, "2.225073858507201e-308"},
  
  	// Issue 2625.
  	{383260575764816448, 'f', 0, "383260575764816448"},
  	{383260575764816448, 'g', -1, "3.8326057576481645e+17"},
  }
  
  func TestFtoa(t *testing.T) {
  	for i := 0; i < len(ftoatests); i++ {
  		test := &ftoatests[i]
  		s := FormatFloat(test.f, test.fmt, test.prec, 64)
  		if s != test.s {
  			t.Error("testN=64", test.f, string(test.fmt), test.prec, "want", test.s, "got", s)
  		}
  		x := AppendFloat([]byte("abc"), test.f, test.fmt, test.prec, 64)
  		if string(x) != "abc"+test.s {
  			t.Error("AppendFloat testN=64", test.f, string(test.fmt), test.prec, "want", "abc"+test.s, "got", string(x))
  		}
  		if float64(float32(test.f)) == test.f && test.fmt != 'b' {
  			s := FormatFloat(test.f, test.fmt, test.prec, 32)
  			if s != test.s {
  				t.Error("testN=32", test.f, string(test.fmt), test.prec, "want", test.s, "got", s)
  			}
  			x := AppendFloat([]byte("abc"), test.f, test.fmt, test.prec, 32)
  			if string(x) != "abc"+test.s {
  				t.Error("AppendFloat testN=32", test.f, string(test.fmt), test.prec, "want", "abc"+test.s, "got", string(x))
  			}
  		}
  	}
  }
  
  func TestFtoaRandom(t *testing.T) {
  	N := int(1e4)
  	if testing.Short() {
  		N = 100
  	}
  	t.Logf("testing %d random numbers with fast and slow FormatFloat", N)
  	for i := 0; i < N; i++ {
  		bits := uint64(rand.Uint32())<<32 | uint64(rand.Uint32())
  		x := math.Float64frombits(bits)
  
  		shortFast := FormatFloat(x, 'g', -1, 64)
  		SetOptimize(false)
  		shortSlow := FormatFloat(x, 'g', -1, 64)
  		SetOptimize(true)
  		if shortSlow != shortFast {
  			t.Errorf("%b printed as %s, want %s", x, shortFast, shortSlow)
  		}
  
  		prec := rand.Intn(12) + 5
  		shortFast = FormatFloat(x, 'e', prec, 64)
  		SetOptimize(false)
  		shortSlow = FormatFloat(x, 'e', prec, 64)
  		SetOptimize(true)
  		if shortSlow != shortFast {
  			t.Errorf("%b printed as %s, want %s", x, shortFast, shortSlow)
  		}
  	}
  }
  
  var ftoaBenches = []struct {
  	name    string
  	float   float64
  	fmt     byte
  	prec    int
  	bitSize int
  }{
  	{"Decimal", 33909, 'g', -1, 64},
  	{"Float", 339.7784, 'g', -1, 64},
  	{"Exp", -5.09e75, 'g', -1, 64},
  	{"NegExp", -5.11e-95, 'g', -1, 64},
  
  	{"Big", 123456789123456789123456789, 'g', -1, 64},
  	{"BinaryExp", -1, 'b', -1, 64},
  
  	{"32Integer", 33909, 'g', -1, 32},
  	{"32ExactFraction", 3.375, 'g', -1, 32},
  	{"32Point", 339.7784, 'g', -1, 32},
  	{"32Exp", -5.09e25, 'g', -1, 32},
  	{"32NegExp", -5.11e-25, 'g', -1, 32},
  
  	{"64Fixed1", 123456, 'e', 3, 64},
  	{"64Fixed2", 123.456, 'e', 3, 64},
  	{"64Fixed3", 1.23456e+78, 'e', 3, 64},
  	{"64Fixed4", 1.23456e-78, 'e', 3, 64},
  
  	// Trigger slow path (see issue #15672).
  	{"Slowpath64", 622666234635.3213e-320, 'e', -1, 64},
  }
  
  func BenchmarkFormatFloat(b *testing.B) {
  	for _, c := range ftoaBenches {
  		b.Run(c.name, func(b *testing.B) {
  			for i := 0; i < b.N; i++ {
  				FormatFloat(c.float, c.fmt, c.prec, c.bitSize)
  			}
  		})
  	}
  }
  
  func BenchmarkAppendFloat(b *testing.B) {
  	dst := make([]byte, 30)
  	for _, c := range ftoaBenches {
  		b.Run(c.name, func(b *testing.B) {
  			for i := 0; i < b.N; i++ {
  				AppendFloat(dst[:0], c.float, c.fmt, c.prec, c.bitSize)
  			}
  		})
  	}
  }
  

View as plain text