// frequently used to compute short identities for binary

// or text blobs. For example, the [git revision control

// system](http://git-scm.com/) uses SHA1s extensively to

// identify versioned files and directories. Here's how to

// compute SHA1 hashes in Go.

​

package main

​

// Go implements several hash functions in various

// `crypto/*` packages.

import "crypto/sha1"

import "fmt"

​

func main() {

    s := "sha1 this string"

​

    // The pattern for generating a hash is `sha1.New()`,

    // `sha1.Write(bytes)`, then `sha1.Sum([]byte{})`.

    // Here we start with a new hash.

    h := sha1.New()

​

    // `Write` expects bytes. If you have a string `s`,

    // use `[]byte(s)` to coerce it to bytes.

    h.Write([]byte(s))

​

    // This gets the finalized hash result as a byte

    // slice. The argument to `Sum` can be used to append

    // to an existing byte slice: it usually isn't needed.

    bs := h.Sum(nil)

​

    // SHA1 values are often printed in hex, for example

    // in git commits. Use the `%x` format verb to convert

    // a hash results to a hex string.

    fmt.Println(s)

    fmt.Printf("%x\n", bs)

}

​