Flag is a package Qanda.ren library that the Go Standard library provides parsing command-line arguments

Flag

Flag is the package that the Go standard library provides to parse the command-line arguments.

Flag is a package Qanda.ren library that the Go Standard library provides parsing command-line arguments

How to use:

Flag. Type (name, defvalue, usage)

Where type is a string, Int, bool, and so on, and returns a pointer of the corresponding type.

Flag. Typevar (&flagvar, name, defvalue, usage)

Binds the flag to a variable.

Custom Flag

Just implement flag. The value interface can:

Type Value Interface {

String () string

Set (String) error

}

Define the flag in the following way:

Flag. Var (&flagvar, name, usage)

Example

Package Main

Import "Flag"

Import "FMT"

Import "StrConv"

Type percentage float32

Func (P *percentage) Set (s string) error {

V, err: = StrConv. Parsefloat (S, 32)

*p = percentage (v)

return err

}

Func (P *percentage) string () string {return FMT. Sprintf ("%f", *p)}

Func Main () {

Nameptr: = flag. String ("name", "Lyh", "User ' name")

Ageptr: = flag. Int ("Age", page, "User's Age")

Vipptr: = flag. Bool ("VIP", True, "is a VIP user")

var email string

Flag. Stringvar (&email, "email", "[email protected]", "User's email")

var pop percentage

Flag. Var (&pop, "Pop", "popularity")

Flag. Parse ()

Others: = flag. Args ()

Fmt. Println ("Name:", *nameptr)

Fmt. Println ("Age:", *ageptr)

Fmt. Println ("VIP:", *vipptr)

Fmt. Println ("Pop:", pop)

Fmt. Println ("Email:", email)

Fmt. Println ("Other:", others)

}

$./command-line-flags

Name:lyh

Age:22

Vip:true

Email: [Email protected]

Other: []

$./command-line-flags-name golang-age 4-vip=true-pop 99 simple, high concurrency, etc.

Name:golang

Age:4

Vip:true

pop:99

Email: [Email protected]

Other: [Simple high concurrency, etc.]

$./command-line-flags-h

Usage of./command-line-flags:

-age=22:user ' s Age

-email= "[Email protected]": User ' s email

-name= "lyh": User ' s name

-pop=0.0:popularity

-vip=true:is a VIP User

Flag is a package Qanda.ren library that the Go Standard library provides parsing command-line arguments