Read line in golang | 易学教程

问题

There are so many option to do this in Go. For example:

scanner := bufio.NewScanner(os.Stdin)
for scanner.Scan() {
    fmt.Println(scanner.Text())
}

reader := bufio.NewReader(os.Stdin)
text, _ := reader.ReadString('\n')

Neither is working in my case. I am unable to find the reason why new line scan is not working.

Here's the question I'm working on: https://www.hackerrank.com/challenges/30-dictionaries-and-maps

And here's my code:

package main
import (
    "fmt"
    "bufio"
    "os"
    "strings"
)

func main() {
    var count int
    fmt.Scan(&count)

    m := make(map[string]string)
    for i := 0; i<count; i++{
        reader := bufio.NewReader(os.Stdin)
        text,err := reader.ReadString('\n')
        if err != nil {
           fmt.Println(err)
        }
        value := strings.Fields(text)
        m[value[0]] = value[1]
    }
    var names []string
    for i := 0; i<count; i++{
        var name string
        fmt.Scan(&name)
        names = append(names,name)
    }

    for j:= 0; j<len(names);j++{
        if m[names[j]] != ""{
            fmt.Println(names[j] +" = "+ m[names[j]])
        }else{
            fmt.Println("Not found")
        }

    }

}

It is working in my editor, but when I use the question's input, it doesn't work.

回答1:

As requested in the comments, here was my working example:

package main

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

func main() {
    phonebook := make(map[string]int)

    var count int
    fmt.Scan(&count)
    for i := 0; i < count; i++ {
        var name string
        var number int
        fmt.Scan(&name, &number)
        phonebook[name] = number
    }

    scanner := bufio.NewScanner(os.Stdin)
    for scanner.Scan() {
        name := scanner.Text()
        if number, ok := phonebook[name]; ok {
            fmt.Printf("%s=%d\n", name, number)
        } else {
            fmt.Println("Not found")
        }
    }
}

回答2:

First of all, you initiate your reader each time in a loop.
Second, if you go with Reader, stick with it. You initialize input reader, then try to go back to fmt.Scan, but Reader already got your input.
Third, remember that you need to .Trim() your input

    package main

    import (
            "fmt"
    "bufio"
    "os"
    "strings"
    )

    func main() {
        var count int
        fmt.Scan(&count)
        reader := bufio.NewReader(os.Stdin)
        m := make(map[string]string)
        for i := 0; i<count; i++{

            text,err := reader.ReadString('\n')
            if err != nil {
                fmt.Println(err)
            }
            value := strings.Fields(text)
            m[value[0]] = value[1]
        }
        var names []string
        for i := 0; i<count; i++{
            var name string
            name, _ = reader.ReadString('\n')
            names = append(names,strings.Trim(name, " \n"))
        }

        for _, name := range names {

            phone, found := m[name]
            if found {
                fmt.Println(name +"="+ phone)
            }else{
                fmt.Println("Not found")
            }

        }

    }

来源：https://stackoverflow.com/questions/40035635/read-line-in-golang

标签

reader