example_test.go

Documentation: io/ioutil

		 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 ioutil_test
		 6  
		 7  import (
		 8  	"fmt"
		 9  	"io/ioutil"
		10  	"log"
		11  	"os"
		12  	"path/filepath"
		13  	"strings"
		14  )
		15  
		16  func ExampleReadAll() {
		17  	r := strings.NewReader("Go is a general-purpose language designed with systems programming in mind.")
		18  
		19  	b, err := ioutil.ReadAll(r)
		20  	if err != nil {
		21  		log.Fatal(err)
		22  	}
		23  
		24  	fmt.Printf("%s", b)
		25  
		26  	// Output:
		27  	// Go is a general-purpose language designed with systems programming in mind.
		28  }
		29  
		30  func ExampleReadDir() {
		31  	files, err := ioutil.ReadDir(".")
		32  	if err != nil {
		33  		log.Fatal(err)
		34  	}
		35  
		36  	for _, file := range files {
		37  		fmt.Println(file.Name())
		38  	}
		39  }
		40  
		41  func ExampleTempDir() {
		42  	content := []byte("temporary file's content")
		43  	dir, err := ioutil.TempDir("", "example")
		44  	if err != nil {
		45  		log.Fatal(err)
		46  	}
		47  
		48  	defer os.RemoveAll(dir) // clean up
		49  
		50  	tmpfn := filepath.Join(dir, "tmpfile")
		51  	if err := ioutil.WriteFile(tmpfn, content, 0666); err != nil {
		52  		log.Fatal(err)
		53  	}
		54  }
		55  
		56  func ExampleTempDir_suffix() {
		57  	parentDir := os.TempDir()
		58  	logsDir, err := ioutil.TempDir(parentDir, "*-logs")
		59  	if err != nil {
		60  		log.Fatal(err)
		61  	}
		62  	defer os.RemoveAll(logsDir) // clean up
		63  
		64  	// Logs can be cleaned out earlier if needed by searching
		65  	// for all directories whose suffix ends in *-logs.
		66  	globPattern := filepath.Join(parentDir, "*-logs")
		67  	matches, err := filepath.Glob(globPattern)
		68  	if err != nil {
		69  		log.Fatalf("Failed to match %q: %v", globPattern, err)
		70  	}
		71  
		72  	for _, match := range matches {
		73  		if err := os.RemoveAll(match); err != nil {
		74  			log.Printf("Failed to remove %q: %v", match, err)
		75  		}
		76  	}
		77  }
		78  
		79  func ExampleTempFile() {
		80  	content := []byte("temporary file's content")
		81  	tmpfile, err := ioutil.TempFile("", "example")
		82  	if err != nil {
		83  		log.Fatal(err)
		84  	}
		85  
		86  	defer os.Remove(tmpfile.Name()) // clean up
		87  
		88  	if _, err := tmpfile.Write(content); err != nil {
		89  		log.Fatal(err)
		90  	}
		91  	if err := tmpfile.Close(); err != nil {
		92  		log.Fatal(err)
		93  	}
		94  }
		95  
		96  func ExampleTempFile_suffix() {
		97  	content := []byte("temporary file's content")
		98  	tmpfile, err := ioutil.TempFile("", "example.*.txt")
		99  	if err != nil {
	 100  		log.Fatal(err)
	 101  	}
	 102  
	 103  	defer os.Remove(tmpfile.Name()) // clean up
	 104  
	 105  	if _, err := tmpfile.Write(content); err != nil {
	 106  		tmpfile.Close()
	 107  		log.Fatal(err)
	 108  	}
	 109  	if err := tmpfile.Close(); err != nil {
	 110  		log.Fatal(err)
	 111  	}
	 112  }
	 113  
	 114  func ExampleReadFile() {
	 115  	content, err := ioutil.ReadFile("testdata/hello")
	 116  	if err != nil {
	 117  		log.Fatal(err)
	 118  	}
	 119  
	 120  	fmt.Printf("File contents: %s", content)
	 121  
	 122  	// Output:
	 123  	// File contents: Hello, Gophers!
	 124  }
	 125  
	 126  func ExampleWriteFile() {
	 127  	message := []byte("Hello, Gophers!")
	 128  	err := ioutil.WriteFile("hello", message, 0644)
	 129  	if err != nil {
	 130  		log.Fatal(err)
	 131  	}
	 132  }
	 133
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