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41 lines
680 B
Go
41 lines
680 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 73.
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// Comma prints its argument numbers with a comma at each power of 1000.
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//
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// Example:
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// $ go build gopl.io/ch3/comma
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// $ ./comma 1 12 123 1234 1234567890
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// 1
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// 12
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// 123
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// 1,234
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// 1,234,567,890
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//
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package main
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import (
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"fmt"
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"os"
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)
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func main() {
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for i := 1; i < len(os.Args); i++ {
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fmt.Printf(" %s\n", comma(os.Args[i]))
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}
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}
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//!+
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// comma inserts commas in a non-negative decimal integer string.
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func comma(s string) string {
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n := len(s)
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if n <= 3 {
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return s
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}
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return comma(s[:n-3]) + "," + s[n-3:]
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}
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//!-
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