30-HasAndChecksum2.go

package main

import (
	"crypto/md5"
	"fmt"
	"io"
	"log"
	"os"
)

func main() {

	/*
	   Hashing and Checksums
	*/

	// Open file for reading
	file, err := os.Open("test.txt")
	if err != nil {
		log.Fatal(err)
	}
	defer file.Close()

	// Create new hasher, which is a writer interface
	hasher := md5.New()
	_, err = io.Copy(hasher, file)
	if err != nil {
		log.Fatal(err)
	}

	sum := hasher.Sum(nil)
	fmt.Printf("Md5 checksum: %x\n", sum)
}