1 // Copyright 2009 The Go Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style
3 // license that can be found in the LICENSE file.
14 type ftoaTest struct {
21 func fdiv(a, b float64) float64 { return a / b } // keep compiler in the dark
24 below1e23 = 99999999999999974834176
25 above1e23 = 100000000000000008388608
28 var ftoatests = []ftoaTest{
29 {1, 'e', 5, "1.00000e+00"},
30 {1, 'f', 5, "1.00000"},
34 {1234567.8, 'g', -1, "1.2345678e+06"},
35 {200000, 'g', -1, "200000"},
36 {2000000, 'g', -1, "2e+06"},
38 // g conversion and zero suppression
39 {400, 'g', 2, "4e+02"},
43 {.04, 'g', 2, "0.04"},
44 {.004, 'g', 2, "0.004"},
45 {.0004, 'g', 2, "0.0004"},
46 {.00004, 'g', 2, "4e-05"},
47 {.000004, 'g', 2, "4e-06"},
49 {0, 'e', 5, "0.00000e+00"},
50 {0, 'f', 5, "0.00000"},
54 {-1, 'e', 5, "-1.00000e+00"},
55 {-1, 'f', 5, "-1.00000"},
59 {12, 'e', 5, "1.20000e+01"},
60 {12, 'f', 5, "12.00000"},
64 {123456700, 'e', 5, "1.23457e+08"},
65 {123456700, 'f', 5, "123456700.00000"},
66 {123456700, 'g', 5, "1.2346e+08"},
67 {123456700, 'g', -1, "1.234567e+08"},
69 {1.2345e6, 'e', 5, "1.23450e+06"},
70 {1.2345e6, 'f', 5, "1234500.00000"},
71 {1.2345e6, 'g', 5, "1.2345e+06"},
73 {1e23, 'e', 17, "9.99999999999999916e+22"},
74 {1e23, 'f', 17, "99999999999999991611392.00000000000000000"},
75 {1e23, 'g', 17, "9.9999999999999992e+22"},
77 {1e23, 'e', -1, "1e+23"},
78 {1e23, 'f', -1, "100000000000000000000000"},
79 {1e23, 'g', -1, "1e+23"},
81 {below1e23, 'e', 17, "9.99999999999999748e+22"},
82 {below1e23, 'f', 17, "99999999999999974834176.00000000000000000"},
83 {below1e23, 'g', 17, "9.9999999999999975e+22"},
85 {below1e23, 'e', -1, "9.999999999999997e+22"},
86 {below1e23, 'f', -1, "99999999999999970000000"},
87 {below1e23, 'g', -1, "9.999999999999997e+22"},
89 {above1e23, 'e', 17, "1.00000000000000008e+23"},
90 {above1e23, 'f', 17, "100000000000000008388608.00000000000000000"},
91 {above1e23, 'g', 17, "1.0000000000000001e+23"},
93 {above1e23, 'e', -1, "1.0000000000000001e+23"},
94 {above1e23, 'f', -1, "100000000000000010000000"},
95 {above1e23, 'g', -1, "1.0000000000000001e+23"},
97 {fdiv(5e-304, 1e20), 'g', -1, "5e-324"},
98 {fdiv(-5e-304, 1e20), 'g', -1, "-5e-324"},
101 {32, 'g', 0, "3e+01"},
103 {100, 'x', -1, "%x"},
105 {math.NaN(), 'g', -1, "NaN"},
106 {-math.NaN(), 'g', -1, "NaN"},
107 {math.Inf(0), 'g', -1, "+Inf"},
108 {math.Inf(-1), 'g', -1, "-Inf"},
109 {-math.Inf(0), 'g', -1, "-Inf"},
111 {-1, 'b', -1, "-4503599627370496p-52"},
114 {0.9, 'f', 1, "0.9"},
115 {0.09, 'f', 1, "0.1"},
116 {0.0999, 'f', 1, "0.1"},
117 {0.05, 'f', 1, "0.1"},
119 {0.5, 'f', 1, "0.5"},
123 // http://www.exploringbinary.com/java-hangs-when-converting-2-2250738585072012e-308/
124 {2.2250738585072012e-308, 'g', -1, "2.2250738585072014e-308"},
125 // http://www.exploringbinary.com/php-hangs-on-numeric-value-2-2250738585072011e-308/
126 {2.2250738585072011e-308, 'g', -1, "2.225073858507201e-308"},
129 {383260575764816448, 'f', 0, "383260575764816448"},
130 {383260575764816448, 'g', -1, "3.8326057576481645e+17"},
133 func TestFtoa(t *testing.T) {
134 for i := 0; i < len(ftoatests); i++ {
135 test := &ftoatests[i]
136 s := FormatFloat(test.f, test.fmt, test.prec, 64)
138 t.Error("testN=64", test.f, string(test.fmt), test.prec, "want", test.s, "got", s)
140 x := AppendFloat([]byte("abc"), test.f, test.fmt, test.prec, 64)
141 if string(x) != "abc"+test.s {
142 t.Error("AppendFloat testN=64", test.f, string(test.fmt), test.prec, "want", "abc"+test.s, "got", string(x))
144 if float64(float32(test.f)) == test.f && test.fmt != 'b' {
145 s := FormatFloat(test.f, test.fmt, test.prec, 32)
147 t.Error("testN=32", test.f, string(test.fmt), test.prec, "want", test.s, "got", s)
149 x := AppendFloat([]byte("abc"), test.f, test.fmt, test.prec, 32)
150 if string(x) != "abc"+test.s {
151 t.Error("AppendFloat testN=32", test.f, string(test.fmt), test.prec, "want", "abc"+test.s, "got", string(x))
157 func TestFtoaRandom(t *testing.T) {
162 t.Logf("testing %d random numbers with fast and slow FormatFloat", N)
163 for i := 0; i < N; i++ {
164 bits := uint64(rand.Uint32())<<32 | uint64(rand.Uint32())
165 x := math.Float64frombits(bits)
166 shortFast := FormatFloat(x, 'g', -1, 64)
168 shortSlow := FormatFloat(x, 'g', -1, 64)
170 if shortSlow != shortFast {
171 t.Errorf("%b printed as %s, want %s", x, shortFast, shortSlow)
176 /* This test relies on escape analysis which gccgo does not yet do.
178 func TestAppendFloatDoesntAllocate(t *testing.T) {
179 n := numAllocations(func() {
181 AppendFloat(buf[:0], 1.23, 'g', 5, 64)
183 want := 1 // TODO(bradfitz): this might be 0, once escape analysis is better
185 t.Errorf("with local buffer, did %d allocations, want %d", n, want)
187 n = numAllocations(func() {
188 AppendFloat(globalBuf[:0], 1.23, 'g', 5, 64)
191 t.Errorf("with reused buffer, did %d allocations, want 0", n)
197 func BenchmarkFormatFloatDecimal(b *testing.B) {
198 for i := 0; i < b.N; i++ {
199 FormatFloat(33909, 'g', -1, 64)
203 func BenchmarkFormatFloat(b *testing.B) {
204 for i := 0; i < b.N; i++ {
205 FormatFloat(339.7784, 'g', -1, 64)
209 func BenchmarkFormatFloatExp(b *testing.B) {
210 for i := 0; i < b.N; i++ {
211 FormatFloat(-5.09e75, 'g', -1, 64)
215 func BenchmarkFormatFloatNegExp(b *testing.B) {
216 for i := 0; i < b.N; i++ {
217 FormatFloat(-5.11e-95, 'g', -1, 64)
221 func BenchmarkFormatFloatBig(b *testing.B) {
222 for i := 0; i < b.N; i++ {
223 FormatFloat(123456789123456789123456789, 'g', -1, 64)
227 func BenchmarkAppendFloatDecimal(b *testing.B) {
228 dst := make([]byte, 0, 30)
229 for i := 0; i < b.N; i++ {
230 AppendFloat(dst, 33909, 'g', -1, 64)
234 func BenchmarkAppendFloat(b *testing.B) {
235 dst := make([]byte, 0, 30)
236 for i := 0; i < b.N; i++ {
237 AppendFloat(dst, 339.7784, 'g', -1, 64)
241 func BenchmarkAppendFloatExp(b *testing.B) {
242 dst := make([]byte, 0, 30)
243 for i := 0; i < b.N; i++ {
244 AppendFloat(dst, -5.09e75, 'g', -1, 64)
248 func BenchmarkAppendFloatNegExp(b *testing.B) {
249 dst := make([]byte, 0, 30)
250 for i := 0; i < b.N; i++ {
251 AppendFloat(dst, -5.11e-95, 'g', -1, 64)
255 func BenchmarkAppendFloatBig(b *testing.B) {
256 dst := make([]byte, 0, 30)
257 for i := 0; i < b.N; i++ {
258 AppendFloat(dst, 123456789123456789123456789, 'g', -1, 64)