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package main
import (
"fmt"
"io"
"os"
)
var path = "/Users/novalagung/Documents/temp/test.txt"
func main() {
createFile()
writeFile()
readFile()
deleteFile()
}
func createFile() {
// detect if file exists
var _, err = os.Stat(path)
// create file if not exists
if os.IsNotExist(err) {
var file, err = os.Create(path)
if isError(err) { return }
defer file.Close()
}
fmt.Println("==> done creating file", path)
}
func writeFile() {
// open file using READ & WRITE permission
var file, err = os.OpenFile(path, os.O_RDWR, 0644)
if isError(err) { return }
defer file.Close()
// write some text line-by-line to file
_, err = file.WriteString("halo\n")
if isError(err) { return }
_, err = file.WriteString("mari belajar golang\n")
if isError(err) { return }
// save changes
err = file.Sync()
if isError(err) { return }
fmt.Println("==> done writing to file")
}
func readFile() {
// re-open file
var file, err = os.OpenFile(path, os.O_RDWR, 0644)
if isError(err) { return }
defer file.Close()
// read file, line by line
var text = make([]byte, 1024)
for {
_, err = file.Read(text)
// break if finally arrived at end of file
if err == io.EOF {
break
}
// break if error occured
if err != nil && err != io.EOF {
isError(err)
break
}
}
fmt.Println("==> done reading from file")
fmt.Println(string(text))
}
func deleteFile() {
// delete file
var err = os.Remove(path)
if isError(err) { return }
fmt.Println("==> done deleting file")
}
func isError(err error) bool {
if err != nil {
fmt.Println(err.Error())
}
return (err != nil)
}
@svigne1
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svigne1 commented Nov 21, 2016

Thank you!

@SerkanSipahi
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SerkanSipahi commented Apr 1, 2017

@milosgajdos83 :)

@lukeramsden
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lukeramsden commented Apr 4, 2017

@milosgajdos83 Would that matter though? Because if the program is exiting, it doesn't need to run the deferred functions. Either way, he could've just used fmt.Fatal().

@yutongz
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yutongz commented May 8, 2017

Helpful for me

@joe94
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joe94 commented May 30, 2017

Like some of you have already suggested, this approach has some bugs. Remember that "defers will not be run when using os.Exit" (https://gobyexample.com/exit).
I fix that issue here: https://gist.github.com/joe94/9725e84392654fbb68ff16053ea6d5bf

@novalagung
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Author

novalagung commented Jul 7, 2017

@milosgajdos83 @joe94 thanks for the responses. I just modified the file for better logging. also all os.Exit() statements are removed now

@edwinyoyada
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edwinyoyada commented Aug 8, 2017

cool!

@LyleScott
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LyleScott commented Sep 11, 2017

Hey, this came in handy. I'd rather read code than words explaining it. thanks!

@abousselmi
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abousselmi commented Nov 6, 2017

thanks !

@anikaraj
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anikaraj commented Dec 19, 2017

I am getting " undefine: isError"

@cys920622
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cys920622 commented Jan 29, 2018

Helped me, thanks.

@kwkrisna2
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kwkrisna2 commented Jul 9, 2018

Suwun cak noval

@alexrios
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alexrios commented Aug 29, 2018

Thanks mate!

@dana321
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dana321 commented Dec 5, 2018

Did you know that you can also use the ioutil functions?

import "io/ioutil"

// read file
bytes,err:= ioutil.ReadFile(filename)
if err!=nil{
panic(err)
}
mystringdata:=string(bytes[:])

//write file
err:=ioutil.WriteFile("myfile.txt",[]byte("write this to file"),0644)
if err!=nil{
panic(err)
}

@webninjastar
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webninjastar commented Apr 5, 2019

I think it has an issue in createFile() function. Because I tested the code without test.txt file in the path but there isn't "test.txt" file after running the code.

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