GO语言：文件操作之写入文件及iota生成常量

目录标题

一、Writing files 写入文件
- 1. Writing string to a file 写入字符串
- 2. Writing bytes to a file 写入字节
- 3. Writing strings line by line to a file 一行一行写入
- 4. Appending to a file 添加内容
- 5. Writing to file concurrently 并发写入文件
二、iota 常量生成器

一、Writing files 写入文件

1. Writing string to a file 写入字符串

        package mainimport ("fmt""os")func main() {f, err := os.Create("writing.txt") // 创建文件fmt.Println(err)if err != nil { // 查看是否出错fmt.Println(err)return}l, err := f.WriteString("Hello, World!") // 写入文件fmt.Println(err)if err != nil { // 查看是否出错fmt.Println(err)f.Close()return}fmt.Println(l, "bytes written successfully")err = f.Close()if err != nil { // 查看是否出错fmt.Println(err)return}}// <nil>// <nil>// 13 bytes written successfully

2. Writing bytes to a file 写入字节

        package mainimport ("fmt""os")func main() {f, err := os.Create("bytes")if err != nil {fmt.Println(err)return}d2 := []byte{104, 101, 108, 108, 111, 32, 98, 121, 116, 101, 115}n, err := f.Write(d2)if err != nil {fmt.Println(err)f.Close()return}fmt.Println(n, "Bytes written successfully")err = f.Close()if err != nil {fmt.Println(err)return}}// 11 Bytes written successfully

3. Writing strings line by line to a file 一行一行写入

        package mainimport ("fmt""os")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) // 使用 fmt.Fprintln() 函数将每个元素写入文件if err != nil {fmt.Println(err)return}}err = f.Close()if err != nil {fmt.Println(err)return}fmt.Println("File written successfully")}// File written successfully

4. Appending to a file 添加内容

        package mainimport (  "fmt""os")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")}// File appended successfully

5. Writing to file concurrently 并发写入文件

        package mainimport ("fmt""math/rand""os""sync")func produce(data chan int, wg *sync.WaitGroup) {n := rand.Intn(999) 	// 随机生成999以内的数字传入通道data <- nwg.Done()}func consume(data chan int, done chan bool) {f, err := os.Create("concurrent")		// 创建文件if err != nil {fmt.Println(err)return}for d := range data {_, err = fmt.Fprintln(f, d) 	// 循环添加入文件if err != nil {             	// 如果不为nil则写入失败fmt.Println(err)f.Close()done <- false 	// 传入通道失败return}}err = f.Close() 	// 关闭文件if err != nil {fmt.Println(err)done <- falsereturn}done <- true 	// 关闭通道}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 := <-doneif d {fmt.Println("File written successfully")} else {fmt.Println("File writing failed")}}// File written successfully

读取文件请查看上一篇文章

二、iota 常量生成器

        type WeekDay intconst (Sunday WeekDay = iotaMondayTuesdayWednesdayThursdayFridaySaturday)func main() {fmt.Println(Sunday, Monday, Tuesday, Wednesday, Thursday, Friday, Saturday, WeekDay(2))fmt.Println(WeekDay(0))day := WeekDay(1)switch day {case Sunday:fmt.Println("今天是星期日")case Monday:fmt.Println("今天是星期一")case Tuesday:fmt.Println("今天是星期二")case Wednesday:fmt.Println("今天是星期三")case Thursday:fmt.Println("今天是星期四")case Friday:fmt.Println("今天是星期五")case Saturday:fmt.Println("今天是星期六")default:fmt.Println("无效的星期")}}// 0 1 2 3 4 5 6 2// 0// 今天是星期一