## 寫文件 ### 將字符串寫入文件 ~~~ func main() { var ( f *os.File err error ) f, err = os.Create("test.txt") defer func() { err = f.Close() if err != nil { fmt.Println("close file failed") } }() if err != nil { fmt.Println("create file failed") return } f.WriteString("Hello World! go") } ~~~ ### 將字節寫入文件 ~~~go func main() { f, err := os.Create("/home/naveen/bytes") if err != nil { fmt.Println(err) return } d2 := []byte{104, 101, 108, 108, 111, 32, 119, 111, 114, 108, 100} n2, err := f.Write(d2) if err != nil { fmt.Println(err) f.Close() return } fmt.Println(n2, "bytes written successfully") err = f.Close() if err != nil { fmt.Println(err) return } } ~~~ ### 將字符串一行一行的寫入文件 ~~~go func main() { f, err := os.Create("lines") if err != nil { fmt.Println(err) f.Close() return } d := []string{"Welcome to the world of Go1.", "Go is a compiled language.", "It is easy to learn Go."} for _, v := range d { fmt.Fprintln(f, v) if err != nil { fmt.Println(err) return } } err = f.Close() if err != nil { fmt.Println(err) return } fmt.Println("file written successfully") } ~~~ ### 追加到文件 ~~~go func main() { f, err := os.OpenFile("lines", os.O_APPEND|os.O_WRONLY, 0644) if err != nil { fmt.Println(err) return } newLine := "File handling is easy." _, err = fmt.Fprintln(f, newLine) if err != nil { fmt.Println(err) f.Close() return } err = f.Close() if err != nil { fmt.Println(err) return } fmt.Println("file appended successfully") } ~~~ ### 并發寫文件 ~~~go func produce(data chan int, wg *sync.WaitGroup) { n := rand.Intn(999) data <- n wg.Done() } func consume(data chan int, done chan bool) { f, err := os.Create("concurrent") if err != nil { fmt.Println(err) return } for d := range data { _, err = fmt.Fprintln(f, d) if err != nil { fmt.Println(err) f.Close() done <- false return } } err = f.Close() if err != nil { fmt.Println(err) done <- false return } done <- true } func main() { data := make(chan int) done := make(chan bool) wg := sync.WaitGroup{} for i := 0; i < 100; i++ { wg.Add(1) go produce(data, &wg) } go consume(data, done) go func() { wg.Wait() close(data) }() d := <-done if d == true { fmt.Println("File written successfully") } else { fmt.Println("File writing failed") } } ~~~