39 lines
955 B
Go
39 lines
955 B
Go
// Copyright © 2018 Inanc Gumus
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// Learn Go Programming Course
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// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
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//
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// For more tutorials : https://learngoprogramming.com
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// In-person training : https://www.linkedin.com/in/inancgumus/
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// Follow me on twitter: https://twitter.com/inancgumus
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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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"strconv"
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)
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func main() {
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// UNCOMMENT THIS TO SEE IT IN ACTION:
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// var n int
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if a := os.Args; len(a) != 2 {
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fmt.Println("Give me a number.")
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} else if n, err := strconv.Atoi(a[1]); err != nil {
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// else if here shadows the main func's n
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// variable and it declares it own
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// with the same name: n
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fmt.Printf("Cannot convert %q.\n", a[1])
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} else {
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fmt.Printf("%s * 2 is %d\n", a[1], n*2)
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}
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// n here belongs to the main func
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// not to the if statement above
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// UNCOMMENT ALSO LINES BELOW TO SEE IT IN ACTION:
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// fmt.Printf("n is %d. 👻 👻 👻 - you've been shadowed ;-)\n", n)
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}
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