Source file
src/strconv/ftoa_test.go
1
2
3
4
5 package strconv_test
6
7 import (
8 "math"
9 "math/rand"
10 . "strconv"
11 "testing"
12 )
13
14 type ftoaTest struct {
15 f float64
16 fmt byte
17 prec int
18 s string
19 }
20
21 func fdiv(a, b float64) float64 { return a / b }
22
23 const (
24 below1e23 = 99999999999999974834176
25 above1e23 = 100000000000000008388608
26 )
27
28 var ftoatests = []ftoaTest{
29 {1, 'e', 5, "1.00000e+00"},
30 {1, 'f', 5, "1.00000"},
31 {1, 'g', 5, "1"},
32 {1, 'g', -1, "1"},
33 {1, 'x', -1, "0x1p+00"},
34 {1, 'x', 5, "0x1.00000p+00"},
35 {20, 'g', -1, "20"},
36 {20, 'x', -1, "0x1.4p+04"},
37 {1234567.8, 'g', -1, "1.2345678e+06"},
38 {1234567.8, 'x', -1, "0x1.2d687cccccccdp+20"},
39 {200000, 'g', -1, "200000"},
40 {200000, 'x', -1, "0x1.86ap+17"},
41 {200000, 'X', -1, "0X1.86AP+17"},
42 {2000000, 'g', -1, "2e+06"},
43 {1e10, 'g', -1, "1e+10"},
44
45
46 {400, 'g', 2, "4e+02"},
47 {40, 'g', 2, "40"},
48 {4, 'g', 2, "4"},
49 {.4, 'g', 2, "0.4"},
50 {.04, 'g', 2, "0.04"},
51 {.004, 'g', 2, "0.004"},
52 {.0004, 'g', 2, "0.0004"},
53 {.00004, 'g', 2, "4e-05"},
54 {.000004, 'g', 2, "4e-06"},
55
56 {0, 'e', 5, "0.00000e+00"},
57 {0, 'f', 5, "0.00000"},
58 {0, 'g', 5, "0"},
59 {0, 'g', -1, "0"},
60 {0, 'x', 5, "0x0.00000p+00"},
61
62 {-1, 'e', 5, "-1.00000e+00"},
63 {-1, 'f', 5, "-1.00000"},
64 {-1, 'g', 5, "-1"},
65 {-1, 'g', -1, "-1"},
66
67 {12, 'e', 5, "1.20000e+01"},
68 {12, 'f', 5, "12.00000"},
69 {12, 'g', 5, "12"},
70 {12, 'g', -1, "12"},
71
72 {123456700, 'e', 5, "1.23457e+08"},
73 {123456700, 'f', 5, "123456700.00000"},
74 {123456700, 'g', 5, "1.2346e+08"},
75 {123456700, 'g', -1, "1.234567e+08"},
76
77 {1.2345e6, 'e', 5, "1.23450e+06"},
78 {1.2345e6, 'f', 5, "1234500.00000"},
79 {1.2345e6, 'g', 5, "1.2345e+06"},
80
81
82 {1.2345e6, 'e', 3, "1.234e+06"},
83 {1.2355e6, 'e', 3, "1.236e+06"},
84 {1.2345, 'f', 3, "1.234"},
85 {1.2355, 'f', 3, "1.236"},
86 {1234567890123456.5, 'e', 15, "1.234567890123456e+15"},
87 {1234567890123457.5, 'e', 15, "1.234567890123458e+15"},
88 {108678236358137.625, 'g', -1, "1.0867823635813762e+14"},
89
90 {1e23, 'e', 17, "9.99999999999999916e+22"},
91 {1e23, 'f', 17, "99999999999999991611392.00000000000000000"},
92 {1e23, 'g', 17, "9.9999999999999992e+22"},
93
94 {1e23, 'e', -1, "1e+23"},
95 {1e23, 'f', -1, "100000000000000000000000"},
96 {1e23, 'g', -1, "1e+23"},
97
98 {below1e23, 'e', 17, "9.99999999999999748e+22"},
99 {below1e23, 'f', 17, "99999999999999974834176.00000000000000000"},
100 {below1e23, 'g', 17, "9.9999999999999975e+22"},
101
102 {below1e23, 'e', -1, "9.999999999999997e+22"},
103 {below1e23, 'f', -1, "99999999999999970000000"},
104 {below1e23, 'g', -1, "9.999999999999997e+22"},
105
106 {above1e23, 'e', 17, "1.00000000000000008e+23"},
107 {above1e23, 'f', 17, "100000000000000008388608.00000000000000000"},
108 {above1e23, 'g', 17, "1.0000000000000001e+23"},
109
110 {above1e23, 'e', -1, "1.0000000000000001e+23"},
111 {above1e23, 'f', -1, "100000000000000010000000"},
112 {above1e23, 'g', -1, "1.0000000000000001e+23"},
113
114 {fdiv(5e-304, 1e20), 'g', -1, "5e-324"},
115 {fdiv(-5e-304, 1e20), 'g', -1, "-5e-324"},
116
117 {32, 'g', -1, "32"},
118 {32, 'g', 0, "3e+01"},
119
120 {100, 'x', -1, "0x1.9p+06"},
121 {100, 'y', -1, "%y"},
122
123 {math.NaN(), 'g', -1, "NaN"},
124 {-math.NaN(), 'g', -1, "NaN"},
125 {math.Inf(0), 'g', -1, "+Inf"},
126 {math.Inf(-1), 'g', -1, "-Inf"},
127 {-math.Inf(0), 'g', -1, "-Inf"},
128
129 {-1, 'b', -1, "-4503599627370496p-52"},
130
131
132 {0.9, 'f', 1, "0.9"},
133 {0.09, 'f', 1, "0.1"},
134 {0.0999, 'f', 1, "0.1"},
135 {0.05, 'f', 1, "0.1"},
136 {0.05, 'f', 0, "0"},
137 {0.5, 'f', 1, "0.5"},
138 {0.5, 'f', 0, "0"},
139 {1.5, 'f', 0, "2"},
140
141
142 {2.2250738585072012e-308, 'g', -1, "2.2250738585072014e-308"},
143
144 {2.2250738585072011e-308, 'g', -1, "2.225073858507201e-308"},
145
146
147 {383260575764816448, 'f', 0, "383260575764816448"},
148 {383260575764816448, 'g', -1, "3.8326057576481645e+17"},
149
150
151 {498484681984085570, 'f', -1, "498484681984085570"},
152 {-5.8339553793802237e+23, 'g', -1, "-5.8339553793802237e+23"},
153
154
155 {123.45, '?', 0, "%?"},
156 {123.45, '?', 1, "%?"},
157 {123.45, '?', -1, "%?"},
158
159
160 {2.275555555555555, 'x', -1, "0x1.23456789abcdep+01"},
161 {2.275555555555555, 'x', 0, "0x1p+01"},
162 {2.275555555555555, 'x', 2, "0x1.23p+01"},
163 {2.275555555555555, 'x', 16, "0x1.23456789abcde000p+01"},
164 {2.275555555555555, 'x', 21, "0x1.23456789abcde00000000p+01"},
165 {2.2755555510520935, 'x', -1, "0x1.2345678p+01"},
166 {2.2755555510520935, 'x', 6, "0x1.234568p+01"},
167 {2.275555431842804, 'x', -1, "0x1.2345668p+01"},
168 {2.275555431842804, 'x', 6, "0x1.234566p+01"},
169 {3.999969482421875, 'x', -1, "0x1.ffffp+01"},
170 {3.999969482421875, 'x', 4, "0x1.ffffp+01"},
171 {3.999969482421875, 'x', 3, "0x1.000p+02"},
172 {3.999969482421875, 'x', 2, "0x1.00p+02"},
173 {3.999969482421875, 'x', 1, "0x1.0p+02"},
174 {3.999969482421875, 'x', 0, "0x1p+02"},
175
176
177 {1.801439850948199e+16, 'g', -1, "1.801439850948199e+16"},
178 {5.960464477539063e-08, 'g', -1, "5.960464477539063e-08"},
179 {1.012e-320, 'g', -1, "1.012e-320"},
180 }
181
182 func TestFtoa(t *testing.T) {
183 for i := 0; i < len(ftoatests); i++ {
184 test := &ftoatests[i]
185 s := FormatFloat(test.f, test.fmt, test.prec, 64)
186 if s != test.s {
187 t.Error("testN=64", test.f, string(test.fmt), test.prec, "want", test.s, "got", s)
188 }
189 x := AppendFloat([]byte("abc"), test.f, test.fmt, test.prec, 64)
190 if string(x) != "abc"+test.s {
191 t.Error("AppendFloat testN=64", test.f, string(test.fmt), test.prec, "want", "abc"+test.s, "got", string(x))
192 }
193 if float64(float32(test.f)) == test.f && test.fmt != 'b' {
194 test_s := test.s
195 if test.f == 5.960464477539063e-08 {
196
197
198 test_s = "5.9604645e-08"
199 continue
200 }
201 s := FormatFloat(test.f, test.fmt, test.prec, 32)
202 if s != test.s {
203 t.Error("testN=32", test.f, string(test.fmt), test.prec, "want", test_s, "got", s)
204 }
205 x := AppendFloat([]byte("abc"), test.f, test.fmt, test.prec, 32)
206 if string(x) != "abc"+test_s {
207 t.Error("AppendFloat testN=32", test.f, string(test.fmt), test.prec, "want", "abc"+test_s, "got", string(x))
208 }
209 }
210 }
211 }
212
213 func TestFtoaPowersOfTwo(t *testing.T) {
214 for exp := -2048; exp <= 2048; exp++ {
215 f := math.Ldexp(1, exp)
216 if !math.IsInf(f, 0) {
217 s := FormatFloat(f, 'e', -1, 64)
218 if x, _ := ParseFloat(s, 64); x != f {
219 t.Errorf("failed roundtrip %v => %s => %v", f, s, x)
220 }
221 }
222 f32 := float32(f)
223 if !math.IsInf(float64(f32), 0) {
224 s := FormatFloat(float64(f32), 'e', -1, 32)
225 if x, _ := ParseFloat(s, 32); float32(x) != f32 {
226 t.Errorf("failed roundtrip %v => %s => %v", f32, s, float32(x))
227 }
228 }
229 }
230 }
231
232 func TestFtoaRandom(t *testing.T) {
233 N := int(1e4)
234 if testing.Short() {
235 N = 100
236 }
237 t.Logf("testing %d random numbers with fast and slow FormatFloat", N)
238 for i := 0; i < N; i++ {
239 bits := uint64(rand.Uint32())<<32 | uint64(rand.Uint32())
240 x := math.Float64frombits(bits)
241
242 shortFast := FormatFloat(x, 'g', -1, 64)
243 SetOptimize(false)
244 shortSlow := FormatFloat(x, 'g', -1, 64)
245 SetOptimize(true)
246 if shortSlow != shortFast {
247 t.Errorf("%b printed as %s, want %s", x, shortFast, shortSlow)
248 }
249
250 prec := rand.Intn(12) + 5
251 shortFast = FormatFloat(x, 'e', prec, 64)
252 SetOptimize(false)
253 shortSlow = FormatFloat(x, 'e', prec, 64)
254 SetOptimize(true)
255 if shortSlow != shortFast {
256 t.Errorf("%b printed as %s, want %s", x, shortFast, shortSlow)
257 }
258 }
259 }
260
261 func TestFormatFloatInvalidBitSize(t *testing.T) {
262 defer func() {
263 if r := recover(); r == nil {
264 t.Fatalf("expected panic due to invalid bitSize")
265 }
266 }()
267 _ = FormatFloat(3.14, 'g', -1, 100)
268 }
269
270 var ftoaBenches = []struct {
271 name string
272 float float64
273 fmt byte
274 prec int
275 bitSize int
276 }{
277 {"Decimal", 33909, 'g', -1, 64},
278 {"Float", 339.7784, 'g', -1, 64},
279 {"Exp", -5.09e75, 'g', -1, 64},
280 {"NegExp", -5.11e-95, 'g', -1, 64},
281 {"LongExp", 1.234567890123456e-78, 'g', -1, 64},
282
283 {"Big", 123456789123456789123456789, 'g', -1, 64},
284 {"BinaryExp", -1, 'b', -1, 64},
285
286 {"32Integer", 33909, 'g', -1, 32},
287 {"32ExactFraction", 3.375, 'g', -1, 32},
288 {"32Point", 339.7784, 'g', -1, 32},
289 {"32Exp", -5.09e25, 'g', -1, 32},
290 {"32NegExp", -5.11e-25, 'g', -1, 32},
291 {"32Shortest", 1.234567e-8, 'g', -1, 32},
292 {"32Fixed8Hard", math.Ldexp(15961084, -125), 'e', 8, 32},
293 {"32Fixed9Hard", math.Ldexp(14855922, -83), 'e', 9, 32},
294
295 {"64Fixed1", 123456, 'e', 3, 64},
296 {"64Fixed2", 123.456, 'e', 3, 64},
297 {"64Fixed3", 1.23456e+78, 'e', 3, 64},
298 {"64Fixed4", 1.23456e-78, 'e', 3, 64},
299 {"64Fixed12", 1.23456e-78, 'e', 12, 64},
300 {"64Fixed16", 1.23456e-78, 'e', 16, 64},
301
302 {"64Fixed12Hard", math.Ldexp(6965949469487146, -249), 'e', 12, 64},
303 {"64Fixed17Hard", math.Ldexp(8887055249355788, 665), 'e', 17, 64},
304 {"64Fixed18Hard", math.Ldexp(6994187472632449, 690), 'e', 18, 64},
305
306
307
308 {"Slowpath64", 8.03413753080882349e+43, 'e', -1, 64},
309
310
311
312
313
314 {"SlowpathDenormal64", 622666234635.3213e-320, 'e', -1, 64},
315 }
316
317 func BenchmarkFormatFloat(b *testing.B) {
318 for _, c := range ftoaBenches {
319 b.Run(c.name, func(b *testing.B) {
320 for i := 0; i < b.N; i++ {
321 FormatFloat(c.float, c.fmt, c.prec, c.bitSize)
322 }
323 })
324 }
325 }
326
327 func BenchmarkAppendFloat(b *testing.B) {
328 dst := make([]byte, 30)
329 for _, c := range ftoaBenches {
330 b.Run(c.name, func(b *testing.B) {
331 for i := 0; i < b.N; i++ {
332 AppendFloat(dst[:0], c.float, c.fmt, c.prec, c.bitSize)
333 }
334 })
335 }
336 }
337
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