for的条件表达式中的“已声明但未使用”变量

Question

My intuitive approach: https://play.golang.org/p/6xzg7TK1IH

and it doesn't work.

Can you share some alternative ways?

Answer 1

You use := which discards the previous contents of the variables. You don't use morelines in that scope, thus the error message.

If you declare your variables beforehand and don't use :=, it works fine. The function ReadLine() might not do what you think it should do.

package main

import (
    "bufio"
    "fmt"
    "log"
    "os"
)

func main() {
    bio := bufio.NewReader(os.Stdin)
    var line []byte
    var err error
    moreline := true
    for moreline {
        line, moreline, err = bio.ReadLine()
        if err != nil {
            log.Fatal(err)
        }
        fmt.Println(line)
    }
}