GO 文件相關操做

package main

import(
	"fmt"
	"os"
	"bufio"
	"io"
	"io/ioutil"
)

type ChartCount struct{
	Chct int
	Spacect int
	Numberct int
	Otherct int
}

func main() {
	file,err := os.Open("./test.txt")
	if err != nil {
		fmt.Println("Open file fail", err)
	}
	defer file.Close()

	reader := bufio.NewReader(file)
	for {
		str,err := reader.ReadString('\n')
		if err == io.EOF {
			break
		}
		fmt.Print(str)
	}

	content,err := ioutil.ReadFile("./test.txt")
	if err != nil {
		fmt.Println("Read file fail ", err)
	}

	fmt.Printf("%v\n", content)
	fmt.Printf("%v\n", string(content))

	//寫文件O_CREATE文件不存在建立, O_TRUNC清空文件, O_APPEND追加, （O_RDWR | O_APPEND)讀寫模式 並追加
	wfile,err := os.OpenFile("./test2.txt", os.O_WRONLY | os.O_CREATE, 0666)
	if err != nil {
		fmt.Println("Open file fail", err)
	}
	defer wfile.Close()

	writer := bufio.NewWriter(wfile)
	wstr  := "hello,world\n"
	for i := 0; i < 5; i++ { 
		writer.WriteString(wstr)
	}
	writer.Flush()

	rcontent,_ := ioutil.ReadFile("./test2.txt") 
	ioutil.WriteFile("./test3.txt", rcontent, 0666) //寫文件

	//判斷文件是否存在
	isexist,iserror := filePathIsExists("./test3.txt")
	if isexist {
		fmt.Println("文件or路徑存在")
	}  else {
		fmt.Println("文件or路徑不存在", iserror)
	}

	//copy文件
	copyFile("./test3.txt", "./test4.log")

	//統計一個文件裏各個字符的個數
	var ct ChartCount
	ct.tj("./testCt.log")
	fmt.Printf("chartct=%v,spaceCt=%v,Numberct=%v,Otherct=%v", ct.Chct, ct.Spacect, ct.Numberct, ct.Otherct)
}

func filePathIsExists (path string) (bool,error) {
	_,error := os.Stat(path)
	if nil == error {
		return true,nil
	}
	if os.IsNotExist(error) {
		return false,nil
	}

	return false,error
}

func copyFile(srcfile string,  dstfile string) (written int64, err error) {
	rfile,err := os.Open(srcfile)
	if err != nil {
		fmt.Println("open rfile fail", err)
	}
	reader := bufio.NewReader(rfile)
	defer rfile.Close()
	wfile,err := os.OpenFile(dstfile, os.O_WRONLY | os.O_CREATE, 0666)
	if err != nil {
		fmt.Println("open wfile fail", err)
	}
	defer wfile.Close()
	writer := bufio.NewWriter(wfile)

	return io.Copy(writer, reader)
}

func (ct *ChartCount) tj(filename string) {
	file,err := os.Open(filename)
	if err != nil {
		fmt.Println("open rfile fail", err)
	}
	reader := bufio.NewReader(file)
	defer file.Close()
	for {
		str,err := reader.ReadString('\n')
		if err == io.EOF {
			break
		}
		for _,v := range str {
			switch{
				case v >= 'a' && v <= 'z':
					fallthrough
				case v >= 'A' && v <= 'Z':
					ct.Chct++
				case v == ' ' || v == '\t':
					ct.Spacect++
				case v >= 0	|| v <= 9:
					ct.Numberct++
				default:
					ct.Otherct++			
			}
		}
	}
}