读文件

package main
import (
    "bufio"
    "fmt"
    "io"
    "io/ioutil"
    "os"
)
func customRead() {
    fileContent, err := os.Open("./shiwo.txt")
    if err != nil {
        fmt.Println("open file error", err)
    }
    defer fileContent.Close()
    var tmp [128]byte
    n, err := fileContent.Read(tmp[:])
    fmt.Println(string(tmp[:n]))
}
func BufioRead() {
    fileContent, err := os.Open("./shiwo.txt")
    if err != nil {
        fmt.Println("open file error", err)
    }
    defer fileContent.Close()
    render := bufio.NewReader(fileContent)
    for {
        //问题：当读到最后时如果最后不存在换行符会导致最后一行无法读取
        line, err := render.ReadString('\n')
        if err == io.EOF {
            return
        }
        if err != nil {
            fmt.Println("render error ", err)
            return
        }
        fmt.Println(line)
    }
}
func IoutilRead() {
    ret, err := ioutil.ReadFile("./shiwo.txt")
    if err != nil {
        fmt.Println("read file error", err)
    }
    fmt.Println(string(ret))
}
func main() {
    customRead()
}

写文件

package main
import (
    "fmt"
    "io/ioutil"
    "os"
)
func IoutilWrite() {
    err := ioutil.WriteFile("./yy.txt", []byte("niwo"), 0664)
    if err != nil {
        fmt.Println("writer file failed", err)
    }
}
func main() {
    //O_RDONLY int = syscall.O_RDONLY // open the file read-only.
    //O_WRONLY int = syscall.O_WRONLY // open the file write-only.
    //O_RDWR   int = syscall.O_RDWR   // open the file read-write.
    //// The remaining values may be or'ed in to control behavior.
    //O_APPEND int = syscall.O_APPEND // append data to the file when writing.
    //O_CREATE int = syscall.O_CREAT  // create a new file if none exists.
    //O_EXCL   int = syscall.O_EXCL   // used with O_CREATE, file must not exist.
    //O_SYNC   int = syscall.O_SYNC   // open for synchronous I/O.
    //O_TRUNC  int = syscall.O_TRUNC // truncate regular writable file when opened.
    //参数说明，OpenFile（文件名，操作模式，文件权限），文件权限只在linux下生效
    file, err := os.OpenFile("./zz.txt", os.O_CREATE|os.O_APPEND, 0644)
    if err != nil {
        fmt.Println("open file failed", err)
    }
    file.WriteString("hahaha")
    file.Close()
}