example_test.go

Documentation: hash

		 1  // Copyright 2017 The Go Authors. All rights reserved.
		 2  // Use of this source code is governed by a BSD-style
		 3  // license that can be found in the LICENSE file.
		 4  
		 5  package hash_test
		 6  
		 7  import (
		 8  	"bytes"
		 9  	"crypto/sha256"
		10  	"encoding"
		11  	"fmt"
		12  	"log"
		13  )
		14  
		15  func Example_binaryMarshaler() {
		16  	const (
		17  		input1 = "The tunneling gopher digs downwards, "
		18  		input2 = "unaware of what he will find."
		19  	)
		20  
		21  	first := sha256.New()
		22  	first.Write([]byte(input1))
		23  
		24  	marshaler, ok := first.(encoding.BinaryMarshaler)
		25  	if !ok {
		26  		log.Fatal("first does not implement encoding.BinaryMarshaler")
		27  	}
		28  	state, err := marshaler.MarshalBinary()
		29  	if err != nil {
		30  		log.Fatal("unable to marshal hash:", err)
		31  	}
		32  
		33  	second := sha256.New()
		34  
		35  	unmarshaler, ok := second.(encoding.BinaryUnmarshaler)
		36  	if !ok {
		37  		log.Fatal("second does not implement encoding.BinaryUnmarshaler")
		38  	}
		39  	if err := unmarshaler.UnmarshalBinary(state); err != nil {
		40  		log.Fatal("unable to unmarshal hash:", err)
		41  	}
		42  
		43  	first.Write([]byte(input2))
		44  	second.Write([]byte(input2))
		45  
		46  	fmt.Printf("%x\n", first.Sum(nil))
		47  	fmt.Println(bytes.Equal(first.Sum(nil), second.Sum(nil)))
		48  	// Output:
		49  	// 57d51a066f3a39942649cd9a76c77e97ceab246756ff3888659e6aa5a07f4a52
		50  	// true
		51  }
		52
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