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// Copyright 2015 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 io_test
import (
"fmt"
"io"
"log"
"os"
"strings"
)
func ExampleCopy() {
r := strings.NewReader("some io.Reader stream to be read\n")
if _, err := io.Copy(os.Stdout, r); err != nil {
log.Fatal(err)
}
// Output:
// some io.Reader stream to be read
}
func ExampleCopyBuffer() {
r1 := strings.NewReader("first reader\n")
r2 := strings.NewReader("second reader\n")
buf := make([]byte, 8)
// buf is used here...
if _, err := io.CopyBuffer(os.Stdout, r1, buf); err != nil {
log.Fatal(err)
}
// ... reused here also. No need to allocate an extra buffer.
if _, err := io.CopyBuffer(os.Stdout, r2, buf); err != nil {
log.Fatal(err)
}
// Output:
// first reader
// second reader
}
func ExampleCopyN() {
r := strings.NewReader("some io.Reader stream to be read")
if _, err := io.CopyN(os.Stdout, r, 4); err != nil {
log.Fatal(err)
}
// Output:
// some
}
func ExampleReadAtLeast() {
r := strings.NewReader("some io.Reader stream to be read\n")
buf := make([]byte, 14)
if _, err := io.ReadAtLeast(r, buf, 4); err != nil {
log.Fatal(err)
}
fmt.Printf("%s\n", buf)
// buffer smaller than minimal read size.
shortBuf := make([]byte, 3)
if _, err := io.ReadAtLeast(r, shortBuf, 4); err != nil {
fmt.Println("error:", err)
}
// minimal read size bigger than io.Reader stream
longBuf := make([]byte, 64)
if _, err := io.ReadAtLeast(r, longBuf, 64); err != nil {
fmt.Println("error:", err)
}
// Output:
// some io.Reader
// error: short buffer
// error: unexpected EOF
}
func ExampleReadFull() {
r := strings.NewReader("some io.Reader stream to be read\n")
buf := make([]byte, 4)
if _, err := io.ReadFull(r, buf); err != nil {
log.Fatal(err)
}
fmt.Printf("%s\n", buf)
// minimal read size bigger than io.Reader stream
longBuf := make([]byte, 64)
if _, err := io.ReadFull(r, longBuf); err != nil {
fmt.Println("error:", err)
}
// Output:
// some
// error: unexpected EOF
}
func ExampleWriteString() {
if _, err := io.WriteString(os.Stdout, "Hello World"); err != nil {
log.Fatal(err)
}
// Output: Hello World
}
func ExampleLimitReader() {
r := strings.NewReader("some io.Reader stream to be read\n")
lr := io.LimitReader(r, 4)
if _, err := io.Copy(os.Stdout, lr); err != nil {
log.Fatal(err)
}
// Output:
// some
}
func ExampleMultiReader() {
r1 := strings.NewReader("first reader ")
r2 := strings.NewReader("second reader ")
r3 := strings.NewReader("third reader\n")
r := io.MultiReader(r1, r2, r3)
if _, err := io.Copy(os.Stdout, r); err != nil {
log.Fatal(err)
}
// Output:
// first reader second reader third reader
}
func ExampleTeeReader() {
var r io.Reader = strings.NewReader("some io.Reader stream to be read\n")
r = io.TeeReader(r, os.Stdout)
// Everything read from r will be copied to stdout.
if _, err := io.ReadAll(r); err != nil {
log.Fatal(err)
}
// Output:
// some io.Reader stream to be read
}
func ExampleSectionReader() {
r := strings.NewReader("some io.Reader stream to be read\n")
s := io.NewSectionReader(r, 5, 17)
if _, err := io.Copy(os.Stdout, s); err != nil {
log.Fatal(err)
}
// Output:
// io.Reader stream
}
func ExampleSectionReader_Read() {
r := strings.NewReader("some io.Reader stream to be read\n")
s := io.NewSectionReader(r, 5, 17)
buf := make([]byte, 9)
if _, err := s.Read(buf); err != nil {
log.Fatal(err)
}
fmt.Printf("%s\n", buf)
// Output:
// io.Reader
}
func ExampleSectionReader_ReadAt() {
r := strings.NewReader("some io.Reader stream to be read\n")
s := io.NewSectionReader(r, 5, 17)
buf := make([]byte, 6)
if _, err := s.ReadAt(buf, 10); err != nil {
log.Fatal(err)
}
fmt.Printf("%s\n", buf)
// Output:
// stream
}
func ExampleSectionReader_Seek() {
r := strings.NewReader("some io.Reader stream to be read\n")
s := io.NewSectionReader(r, 5, 17)
if _, err := s.Seek(10, io.SeekStart); err != nil {
log.Fatal(err)
}
if _, err := io.Copy(os.Stdout, s); err != nil {
log.Fatal(err)
}
// Output:
// stream
}
func ExampleSectionReader_Size() {
r := strings.NewReader("some io.Reader stream to be read\n")
s := io.NewSectionReader(r, 5, 17)
fmt.Println(s.Size())
// Output:
// 17
}
func ExampleSeeker_Seek() {
r := strings.NewReader("some io.Reader stream to be read\n")
r.Seek(5, io.SeekStart) // move to the 5th char from the start
if _, err := io.Copy(os.Stdout, r); err != nil {
log.Fatal(err)
}
r.Seek(-5, io.SeekEnd)
if _, err := io.Copy(os.Stdout, r); err != nil {
log.Fatal(err)
}
// Output:
// io.Reader stream to be read
// read
}
func ExampleMultiWriter() {
r := strings.NewReader("some io.Reader stream to be read\n")
var buf1, buf2 strings.Builder
w := io.MultiWriter(&buf1, &buf2)
if _, err := io.Copy(w, r); err != nil {
log.Fatal(err)
}
fmt.Print(buf1.String())
fmt.Print(buf2.String())
// Output:
// some io.Reader stream to be read
// some io.Reader stream to be read
}
func ExamplePipe() {
r, w := io.Pipe()
go func() {
fmt.Fprint(w, "some io.Reader stream to be read\n")
w.Close()
}()
if _, err := io.Copy(os.Stdout, r); err != nil {
log.Fatal(err)
}
// Output:
// some io.Reader stream to be read
}
func ExampleReadAll() {
r := strings.NewReader("Go is a general-purpose language designed with systems programming in mind.")
b, err := io.ReadAll(r)
if err != nil {
log.Fatal(err)
}
fmt.Printf("%s", b)
// Output:
// Go is a general-purpose language designed with systems programming in mind.
}