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36 lines
696 B
Go
36 lines
696 B
Go
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// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
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// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
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// See page 173.
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// Bytecounter demonstrates an implementation of io.Writer that counts bytes.
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package main
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import (
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"fmt"
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)
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//!+bytecounter
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type ByteCounter int
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func (c *ByteCounter) Write(p []byte) (int, error) {
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*c += ByteCounter(len(p)) // convert int to ByteCounter
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return len(p), nil
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}
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//!-bytecounter
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func main() {
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//!+main
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var c ByteCounter
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c.Write([]byte("hello"))
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fmt.Println(c) // "5", = len("hello")
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c = 0 // reset the counter
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var name = "Dolly"
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fmt.Fprintf(&c, "hello, %s", name)
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fmt.Println(c) // "12", = len("hello, Dolly")
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//!-main
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}
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