A method for parameter parsing of the command line using the flag package in the Go language _golang

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

How to use:

Flag. Type (name, defvalue, usage)

Where type is string, INT, bool, and so on, and returns a pointer to the corresponding type.

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

Bind the flag to a variable.

Custom Flag
as long as the realization of flag. The value interface can:

Type Value Interface {
  string () string
  Set (String) Error
}

The flag is defined by the following methods:

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,) *p = percentage (v) return err} func (P *percentage) string () string {return FMT. Sprintf ("%f", *p)} func main () {nameptr: = flag. String ("name", "Lyh", "User ' s name") Ageptr: = flag. Int ("Age", "User's Age") Vipptr: = flag. Bool ("VIP", True, "is a VIP user") var email string flag. Stringvar (&email, "email", "lyhopq@gmail.com", "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:lyhopq@gmail.com other
: []

$./command-line-flags-name golang-age 4-vip=true-pop 99 Compact High concurrency
name:golang
age:4 vip:true
Pop :
email:lyhopq@gmail.com Other
: [Simple high concurrency and so on]

$/command-line-flags-h
Usage of./command-line-flags:
 -age=22:user ' age
 -email= ' lyhopq@gmail.com ": User ' s email
 -name=" LYH ": User's name
 -pop=0.0:popularity
 -vip=true:is a VIP user