Parse Command-line Flags

package main

import (
    "flag"
    "fmt"
)

func main() {

    // Basic flag declarations are available for string, integer, and boolean options.
    // Here we declare a string flag word with a default value "foo" and a short description.
    // This flag.String function returns a string pointer (not a string value);
    // we’ll see how to use this pointer below.
    wordPtr := flag.String("word", "foo", "a string")

    // This declares numb and fork flags, using a similar approach to the word flag.
    numbPtr := flag.Int("numb", 42, "an int")
    boolPtr := flag.Bool("fork", false, "a bool")

    // It’s also possible to declare an option that uses an existing var declared elsewhere in the program.
    // Note that we need to pass in a pointer to the flag declaration function.
    var svar string
    flag.StringVar(&svar, "svar", "bar", "a string var")

    // Once all flags are declared, call flag.Parse() to execute the command-line parsing.
    flag.Parse()

    fmt.Println("word:", *wordPtr)
    fmt.Println("numb:", *numbPtr)
    fmt.Println("fork:", *boolPtr)
    fmt.Println("svar:", svar)
    fmt.Println("tail:", flag.Args())
}