go 文件操作

package main

import (
    "fmt"
    "os"
)

func main(){
//file指针
    file,err:=os.Open("d:/test.txt")
    if err!=nil{
        fmt.Println("open file err=",err)
    }
    //输出文件
    fmt.Printf("file=%v",file)
    err=file.Close()
    if err!=nil{
        fmt.Println("close file err=",err)
    }
}

package main

import (
    "bufio"
    "fmt"
    "io"
    "os"
)
//逐行读取
func main() {
    file, err := os.Open("d:/test.txt")
    if err != nil {
        fmt.Println("open file err=", err)
    }
    defer file.Close()
    const
    (
        defaultltBufSize = 4096 //默认缓冲区为4096
    )

    reader := bufio.NewReader(file)
    //循环读取文件的内容
    for {
        str, err := reader.ReadString(‘\n‘) //读取到一个换行就结束
        fmt.Print(str)
        if err == io.EOF {
            break
        }

    }

}

package main

import (
    "fmt"
    "io/ioutil"
)

func main(){
    //使用ioutil.ReadFile,一次性将文件读取到位
    file:="d:/test.txt"
    content,err:=ioutil.ReadFile(file)
if err!=nil{
    fmt.Printf("read file err=%v",err)
}
fmt.Printf("%v",string(content))
}

package main

import (
    "bufio"
    "fmt"
    "os"
)

func main(){
    //创建文件并写入
    filePath:="d:/abc.txt"
    file,err:=os.OpenFile(filePath,os.O_WRONLY|os.O_CREATE,0666)
    if err!=nil{
        fmt.Printf("open file err=%v\n",err)
        return
    }


    defer file.Close()
    str:="hello gardon\n"
    writer:=bufio.NewWriter(file)
    for i:=0;i<5;i++{
        writer.WriteString(str)
    }
    writer.Flush()
}

package main

import (
    "bufio"
    "fmt"
    "os"
)

func main(){
    //覆盖文件内容
    filePath:="d:/abc.txt"
    file,err:=os.OpenFile(filePath,os.O_WRONLY|os.O_TRUNC,0666)
    if err!=nil{
        fmt.Printf("open file err=%v\n",err)
        return
    }


    defer file.Close()
    str:="hello kitty\n"
    writer:=bufio.NewWriter(file)
    for i:=0;i<5;i++{
        writer.WriteString(str)
    }
    writer.Flush()
}

package main

import (
    "bufio"
    "fmt"
    "os"
)

func main(){
    //追加文件内容
    filePath:="d:/abc.txt"
    file,err:=os.OpenFile(filePath,os.O_WRONLY|os.O_APPEND,0666)
    if err!=nil{
        fmt.Printf("open file err=%v\n",err)
        return
    }


    defer file.Close()
    str:="我是追加内容\n"
    writer:=bufio.NewWriter(file)
    for i:=0;i<5;i++{
        writer.WriteString(str)
    }
    writer.Flush()
}

package main

import (
    "bufio"
    "fmt"
    "os"
)

func main(){
    //先读取后追加文件内容
    filePath:="d:/abc.txt"
    file,err:=os.OpenFile(filePath,os.O_RDWR|os.O_APPEND,0666)
    if err!=nil{
        fmt.Printf("open file err=%v\n",err)
        return
    }


    defer file.Close()
    str:="我是读取后追加内容\n"
    writer:=bufio.NewWriter(file)
    for i:=0;i<5;i++{
        writer.WriteString(str)
    }
    writer.Flush()
}

package main

import (
    "fmt"
    "io/ioutil"
)

func main(){

    //将一个文件的内容写入另外一个文件
    filepath:="d:/abc.txt"
    filepath2:="d:/kkk.txt"
    data,err:=ioutil.ReadFile(filepath)
    if err!=nil{
        fmt.Printf("read file err=%v",err)
        return
    }
    err=ioutil.WriteFile(filepath2,data,0666)
    if err!=nil{
        fmt.Printf("write file err=%v\n",err)
    }

}

package main

import (
    "fmt"
    "os"
)

func main() {
fmt.Println(PathExists("d:/"))
}

//判断文件.或文件夹是否存在
func PathExists(path string) (bool, error) {
    _, err := os.Stat(path)
    if err == nil {
        return true, nil
    }
    if os.IsNotExist(err) {
        return false, nil
    }
    return false, nil
}

package main

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

//文件拷贝
func CopyFile(dstFileName 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(dstFileName, 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:="d:/flower.jpg"
    dstFile:="e:/abc.jpg"
    _,err:=CopyFile(dstFile,srcFile)
    if err==nil{
        fmt.Print("拷贝完成\n")
    }else{
        fmt.Printf("拷贝错误err=%v",err)
    }
}

package main
import (
    "fmt"
    "os"
    "io"
    "bufio"
)

//定义一个结构体，用于保存统计结果
type CharCount struct {
    ChCount int // 记录英文个数
    NumCount int // 记录数字的个数
    SpaceCount int // 记录空格的个数
    OtherCount int // 记录其它字符的个数
}

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 := "d:/abc.txt"
    file, err := os.Open(fileName)
    if err != nil {
        fmt.Printf("open file err=%v\n", err)
        return
    }
    defer file.Close()
    //定义个CharCount 实例
    var count CharCount
    //创建一个Reader
    reader := bufio.NewReader(file)

    //开始循环的读取fileName的内容
    for {
        str, err := reader.ReadString(‘\n‘)
        if err == io.EOF { //读到文件末尾就退出
            break
        }
        //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++
            }
        }
    }

    //输出统计的结果看看是否正确
    fmt.Printf("字符的个数为=%v 数字的个数为=%v 空格的个数为=%v 其它字符个数=%v",
        count.ChCount, count.NumCount, count.SpaceCount, count.OtherCount)


}