1、拷贝文件

  说明:将一张图片/电影/mp3拷贝到另外一个文件e:/abc.jpg
io包func Copy(dst Writer, src Reader) (written int64, err error)

package mainimport ("bufio""fmt""io""os"
)func CopyFile(destFileName string, srcFileName string) (written int64, err error) {srcFile, err := os.Open(srcFileName)if err != nil {fmt.Printf("open file err=%v\n", err)}defer srcFile.Close()reader := bufio.NewReader(srcFile)dstFile, err := os.OpenFile(destFileName, os.O_WRONLY|os.O_CREATE, 0666)if err != nil {fmt.Printf("open file err=%v\n", err)return}writer := bufio.NewWriter(dstFile)defer dstFile.Close()return io.Copy(writer, reader)
}
func main{srcFile := "src\\file\\file01\\cdntest.jpg"dstFile := "src\\file\\file01\\test.jpg"_, err := CopyFile(dstFile, srcFile)if err == nil {fmt.Printf("拷贝完成\n")} else {fmt.Printf("拷贝错误 err=%v\n", err)}
}

2、统计英文、数字、空格和其他字符数量

package mainimport ("bufio""fmt""io""os"
)type ChartCount struct {ChCount    int //记录英文个数NumCount   int //记录数字字数SpaceCount int //记录空格个数OtherCount int //记录其他字符个数
}
func main{//思路:打开一个文件,创一个Reader//每读取一行，就去统计该行有多少个英文、数字、空格和其他字符//然后将结果保存到一个结构体fileName := "src\\file\\file01\\test.txt"file, err := os.Open(fileName)if err != nil {fmt.Printf("open file err=%v\n", err)return}defer file.Close()//定义一个ChartCount实例var count ChartCountreader := bufio.NewReader(file)//循环读取文件内容for {str, err := reader.ReadString('\n')if err == io.EOF { //读到文件末尾就退出break}//为了兼容中文字符，可以将str转成[]runestr = string([]rune(str))//遍历str，进行统计for _, v := range str {switch {case v >= 'a' && v <= 'z':fallthrough //穿透case v >= 'A' && v <= 'Z':count.ChCount++case v == ' ' || v == '\t':count.SpaceCount++case v >= '0' && v <= '9':count.NumCount++default:count.OtherCount++}}}fmt.Printf("字符的个数为=%v 数字的个数为=%v 空格的个数为=%v 其他字符的个数为=%v",count.ChCount, count.NumCount, count.SpaceCount, count.OtherCount)
}

3、获取命令行参数个数

fmt.Println("命令行参数有", len(os.Args))//遍历os.Args切片，就可以得到所有的命令行输入的参数值for i, v := range os.Args {fmt.Printf("args[%v]=%v\n", i, v)}