Go Systems Programming

The io package

The io package offers functions that allow you to write to or read from files. Its use will be illustrated in the usingIO.go file, which will be presented in three parts. What the program does is read 8 bytes from a file and write them in a standard output.

The first part is the preamble of the Go program:

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

The second part is the following Go code:

func main() { 
   if len(os.Args) != 2 { 
         fmt.Println("Please provide a filename") 
         os.Exit(1) 
   } 
 
   filename := os.Args[1] 
   f, err := os.Open(filename) 
   if err != nil { 
         fmt.Printf("error opening %s: %s", filename, err) 
         os.Exit(1) 
   } 
   defer f.Close() 

The program also uses the handy defer command that defers the execution of a function until the surrounding ...