1 // Copyright 2015 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. 4 5 package io_test 6 7 import ( 8 "bytes" 9 "fmt" 10 "io" 11 "io/ioutil" 12 "log" 13 "os" 14 "strings" 15 ) 16 17 func ExampleCopy() { 18 r := strings.NewReader("some io.Reader stream to be read\n") 19 20 if _, err := io.Copy(os.Stdout, r); err != nil { 21 log.Fatal(err) 22 } 23 24 // Output: 25 // some io.Reader stream to be read 26 } 27 28 func ExampleCopyBuffer() { 29 r1 := strings.NewReader("first reader\n") 30 r2 := strings.NewReader("second reader\n") 31 buf := make([]byte, 8) 32 33 // buf is used here... 34 if _, err := io.CopyBuffer(os.Stdout, r1, buf); err != nil { 35 log.Fatal(err) 36 } 37 38 // ... reused here also. No need to allocate an extra buffer. 39 if _, err := io.CopyBuffer(os.Stdout, r2, buf); err != nil { 40 log.Fatal(err) 41 } 42 43 // Output: 44 // first reader 45 // second reader 46 } 47 48 func ExampleCopyN() { 49 r := strings.NewReader("some io.Reader stream to be read") 50 51 if _, err := io.CopyN(os.Stdout, r, 5); err != nil { 52 log.Fatal(err) 53 } 54 55 // Output: 56 // some 57 } 58 59 func ExampleReadAtLeast() { 60 r := strings.NewReader("some io.Reader stream to be read\n") 61 62 buf := make([]byte, 33) 63 if _, err := io.ReadAtLeast(r, buf, 4); err != nil { 64 log.Fatal(err) 65 } 66 fmt.Printf("%s\n", buf) 67 68 // buffer smaller than minimal read size. 69 shortBuf := make([]byte, 3) 70 if _, err := io.ReadAtLeast(r, shortBuf, 4); err != nil { 71 fmt.Println("error:", err) 72 } 73 74 // minimal read size bigger than io.Reader stream 75 longBuf := make([]byte, 64) 76 if _, err := io.ReadAtLeast(r, longBuf, 64); err != nil { 77 fmt.Println("error:", err) 78 } 79 80 // Output: 81 // some io.Reader stream to be read 82 // 83 // error: short buffer 84 // error: EOF 85 } 86 87 func ExampleReadFull() { 88 r := strings.NewReader("some io.Reader stream to be read\n") 89 90 buf := make([]byte, 4) 91 if _, err := io.ReadFull(r, buf); err != nil { 92 log.Fatal(err) 93 } 94 fmt.Printf("%s\n", buf) 95 96 // minimal read size bigger than io.Reader stream 97 longBuf := make([]byte, 64) 98 if _, err := io.ReadFull(r, longBuf); err != nil { 99 fmt.Println("error:", err) 100 } 101 102 // Output: 103 // some 104 // error: unexpected EOF 105 } 106 107 func ExampleWriteString() { 108 io.WriteString(os.Stdout, "Hello World") 109 110 // Output: Hello World 111 } 112 113 func ExampleLimitReader() { 114 r := strings.NewReader("some io.Reader stream to be read\n") 115 lr := io.LimitReader(r, 4) 116 117 if _, err := io.Copy(os.Stdout, lr); err != nil { 118 log.Fatal(err) 119 } 120 121 // Output: 122 // some 123 } 124 125 func ExampleMultiReader() { 126 r1 := strings.NewReader("first reader ") 127 r2 := strings.NewReader("second reader ") 128 r3 := strings.NewReader("third reader\n") 129 r := io.MultiReader(r1, r2, r3) 130 131 if _, err := io.Copy(os.Stdout, r); err != nil { 132 log.Fatal(err) 133 } 134 135 // Output: 136 // first reader second reader third reader 137 } 138 139 func ExampleTeeReader() { 140 r := strings.NewReader("some io.Reader stream to be read\n") 141 var buf bytes.Buffer 142 tee := io.TeeReader(r, &buf) 143 144 printall := func(r io.Reader) { 145 b, err := ioutil.ReadAll(r) 146 if err != nil { 147 log.Fatal(err) 148 } 149 150 fmt.Printf("%s", b) 151 } 152 153 printall(tee) 154 printall(&buf) 155 156 // Output: 157 // some io.Reader stream to be read 158 // some io.Reader stream to be read 159 } 160 161 func ExampleSectionReader() { 162 r := strings.NewReader("some io.Reader stream to be read\n") 163 s := io.NewSectionReader(r, 5, 17) 164 165 if _, err := io.Copy(os.Stdout, s); err != nil { 166 log.Fatal(err) 167 } 168 169 // Output: 170 // io.Reader stream 171 } 172 173 func ExampleSectionReader_ReadAt() { 174 r := strings.NewReader("some io.Reader stream to be read\n") 175 s := io.NewSectionReader(r, 5, 16) 176 177 buf := make([]byte, 6) 178 if _, err := s.ReadAt(buf, 10); err != nil { 179 log.Fatal(err) 180 } 181 182 fmt.Printf("%s\n", buf) 183 184 // Output: 185 // stream 186 } 187 188 func ExampleSectionReader_Seek() { 189 r := strings.NewReader("some io.Reader stream to be read\n") 190 s := io.NewSectionReader(r, 5, 16) 191 192 if _, err := s.Seek(10, io.SeekStart); err != nil { 193 log.Fatal(err) 194 } 195 196 buf := make([]byte, 6) 197 if _, err := s.Read(buf); err != nil { 198 log.Fatal(err) 199 } 200 201 fmt.Printf("%s\n", buf) 202 203 // Output: 204 // stream 205 } 206 207 func ExampleSeeker_Seek() { 208 r := strings.NewReader("some io.Reader stream to be read\n") 209 if _, err := io.Copy(os.Stdout, r); err != nil { 210 log.Fatal(err) 211 } 212 213 r.Seek(15, io.SeekStart) 214 if _, err := io.Copy(os.Stdout, r); err != nil { 215 log.Fatal(err) 216 } 217 218 r.Seek(-5, io.SeekEnd) 219 if _, err := io.Copy(os.Stdout, r); err != nil { 220 log.Fatal(err) 221 } 222 223 // Output: 224 // some io.Reader stream to be read 225 // stream to be read 226 // read 227 } 228 229 func ExampleMultiWriter() { 230 r := strings.NewReader("some io.Reader stream to be read\n") 231 232 var buf1, buf2 bytes.Buffer 233 w := io.MultiWriter(&buf1, &buf2) 234 235 if _, err := io.Copy(w, r); err != nil { 236 log.Fatal(err) 237 } 238 239 fmt.Print(buf1.String()) 240 fmt.Print(buf2.String()) 241 242 // Output: 243 // some io.Reader stream to be read 244 // some io.Reader stream to be read 245 } 246 247 func ExamplePipe() { 248 r, w := io.Pipe() 249 250 go func() { 251 fmt.Fprint(w, "some text to be read\n") 252 w.Close() 253 }() 254 255 buf := new(bytes.Buffer) 256 buf.ReadFrom(r) 257 fmt.Print(buf.String()) 258 259 // Output: 260 // some text to be read 261 } 262
