Reading and writing

Reading and writing files can be done in numerous ways. Go provides interfaces that make it easy to write your own functions that work with files or any other reader/writer interface.

Between the os, io, and ioutil packages, you can find the right function for your needs. These examples cover a number of the options available.

Copying a file

The following example uses the io.Copy() function to copy the contents from one reader to another writer:

package main 
 
import ( 
   "io" 
   "log" 
   "os" 
) 
 
func main() { 
   // Open original file 
   originalFile, err := os.Open("test.txt") 
   if err != nil { 
      log.Fatal(err) 
   } 
   defer originalFile.Close() 
 
   // Create new file 
   newFile, err := os.Create("test_copy.txt") 
   if err != nil { 
      log.Fatal(err) 
   } 
   defer newFile.Close() 
 
   // Copy the bytes to destination from source 
   bytesWritten, err := io.Copy(newFile, originalFile) 
   if err != nil { 
      log.Fatal(err) 
   } 
   log.Printf...