为什么在输出中忽略_（下划线）？

Question

I would like to know the reason behind the output of this program.

package main

Program

import (
    "fmt"
)

func main() {
    a := 1_00_000
    fmt.Println(a)
}

Output

100000

How come the underscore is ignored in the output. What is the use of this new feature in Go?

Answer 1

It's not ignored in the output; it's ignored in the source code. The underscores are a convenience to make large number literals in code easier to read; the literal is still an integer, and integers don't contain underscores. You could always use a string of course:

a := "1_00_000"
fmt.Println(a)

Underscores as separators were added as a new feature in Go 1.13: https://golang.org/doc/go1.13#language