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The Way to Go

Writing to a File

This lesson provides code examples and their explanations for writing to a file.

We'll cover the following...

Writing data to a file

Writing data to a file is demonstrated in the following program:

Go (1.6.2)
package main
import (
  "os"
  "bufio"
  "fmt"
)
func main () {
  outputFile, outputError := os.OpenFile("output/output.dat", os.O_WRONLY|os.O_CREATE, 0666)
  if outputError != nil {
    fmt.Printf("An error occurred with file creation\n")
    return
  }
  defer outputFile.Close()
  outputWriter:= bufio.NewWriter(outputFile)
  outputString := "hello world!\n"
  for i:=0; i<10; i++ {
    outputWriter.WriteString(outputString)
  }
  outputWriter.Flush()
}

Apart from a filehandle, we now need a writer from bufio. We open a file output.dat for write-only at line 9. The file is created if it does not exist.

The os.OpenFile is a function that allows more control over the opening mode of a file. We see that the OpenFile function takes a filename, one or more flags (logically OR-d together using the | bitwise OR operator if more than one) and the file permissions to use. The following flags ...