Golang : Compare files modify date example

Problem:

You're writing a game that will create multiple save files and you want to compare the save game files modify date for sorting purpose and avoid overwriting older files. You also want the game to load a proper file instead of a directory.

Solution:

Below is a code example on how to compare files modify date and perform simple sanity checks.

Here you go!

---

 package main

 import (
 "fmt"
 "os"
 "time"
 )

 func main() {

 if len(os.Args) != 3 {
 fmt.Printf("Usage : %s <file1> <file2> \n", os.Args[0]) // return the program name back to %s
 fmt.Printf("Compare <file1> <file2> modify date \n")
 os.Exit(0) // graceful exit
 }

 file1 := os.Args[1]
 file2 := os.Args[2]

 // perform sanity checks on file1 and file2

 file1Info, err := os.Stat(file1)
 if err != nil {
 fmt.Printf("%s is not a file. \n", file1)
 os.Exit(-1)
 }

 mode1 := file1Info.Mode()
 if mode1.IsDir() {
 fmt.Printf("%s is a directory, not a file. \n", file1)
 os.Exit(-1)
 }

 file2Info, err := os.Stat(file2)
 if err != nil {
 fmt.Printf("%s is not a file. \n", file2)
 os.Exit(-1)
 }

 mode2 := file2Info.Mode()
 if mode2.IsDir() {
 fmt.Printf("%s is a directory, not a file. \n", file2)
 os.Exit(-1)
 }

 // get last modified date of the files
 modTime1 := file1Info.ModTime()
 modTime2 := file2Info.ModTime()

 diff := modTime1.Sub(modTime2)

 if diff == (time.Duration(0) * time.Second) {
 fmt.Printf("%s has the same last modified timestamp as %s \n", file1, file2)
 }

 if diff < (time.Duration(0) * time.Second) {
 fmt.Printf("%s is older than %s \n", file1, file2)
 }

 if diff > (time.Duration(0) * time.Second) {
 fmt.Printf("%s is younger than %s \n", file1, file2)
 }

 fmt.Printf("file1 is [%s] with last modified time of [%s]\n", file1, modTime1)
 fmt.Printf("file2 is [%s] with last modified time of [%s]\n", file2, modTime2)

 }

Sample output:

./cmpdate writer.dat .atom

.atom is a directory, not a file.

---

./cmpdate writer.dat writexml.go

writer.dat is older than writexml.go

file1 is [writer.dat] with last modified time of [2015-03-25 09:56:27 +0800 SGT]

file2 is [writexml.go] with last modified time of [2015-04-04 16:10:16 +0800 SGT]

---

./cmpdate writer.dat writer.dat

writer.dat has the same last modified timestamp as writer.dat

file1 is [writer.dat] with last modified time of [2015-03-25 09:56:27 +0800 SGT]

file2 is [writer.dat] with last modified time of [2015-03-25 09:56:27 +0800 SGT]

References:

https://www.socketloop.com/tutorials/golang-check-to-see-if-file-is-a-file-or-directory

https://github.com/SimonHung/LodeRunner_TotalRecall/blob/master/tools/cmpDate.cpp

https://www.socketloop.com/tutorials/golang-comparing-date-or-timestamp

https://www.socketloop.com/tutorials/golang-calculate-time-different