从未使用过此预订值 (SA4006)

Question

我正在尝试学习 Golang，当我在 Youtube 上与 Techworld 和 Nana 一起做一个教程，并学习将逻辑与函数分组时，它显示了一个之前没有的错误，并且没有显示她在视频里。

bookTicket(remainingTickets, userTickets, bookings, firstName, lastName, email, conferenceName)

以上是对以下函数的调用：

func bookTicket(remainingTickets uint, userTickets uint, bookings []string, firstName string, lastName string, email string, conferenceName string) {
remainingTickets = remainingTickets - userTickets
bookings = append(bookings, firstName+" "+lastName)

它说“从未使用过此预订值 (SA4006)”

所以，这是完整的代码：

https://go.dev/play/p/GFMR7f64li1

package main

import (
    "fmt"
    "strings"
)

func main() {
    conferenceName := "Go Conference"
    const conferenceTickets int = 50
    var remainingTickets uint = 50
    bookings := []string{}

    greetUsers(conferenceName, conferenceTickets, remainingTickets)

    for {

        firstName, lastName, email, userTickets := getUserInput()

        isValidName, isValidEmail, isValidTicketNumber := validateUserInput(firstName, lastName, email, userTickets, remainingTickets)

        if isValidName && isValidEmail && isValidTicketNumber {

            bookTicket(remainingTickets, userTickets, bookings, firstName, lastName, email, conferenceName)

            firstNames := getFirstNames(bookings)
            fmt.Printf("The first name of our bookings are: %v\n", firstNames)

            if remainingTickets == 0 {
                // sair do loop/programa
                fmt.Println("Our conference is booked out. Come back next year.")
                break
            }
        } else {
            if !isValidName {
                fmt.Println("First name or last name too short.")
            }
            if !isValidEmail {
                fmt.Println("E-mail doesn't contain @ sign.")
            }
            if !isValidTicketNumber {
                fmt.Println("Number of tickets entered is invalid.")
            }

        }

    }

}

func greetUsers(confName string, confTickets int, remainingTickets uint) {
    fmt.Printf("Welcome to %v booking application!\n", confName)
    fmt.Printf("We have a total of %v tickets and %v are still available.\n", confTickets, remainingTickets)
    fmt.Println("Get your tickets here to attend.")

}

func getFirstNames(bookings []string) []string {
    firstNames := []string{}
    for _, booking := range bookings {
        var names = strings.Fields(booking)
        firstNames = append(firstNames, names[0])
    }
    return firstNames
}

func validateUserInput(firstName string, lastName string, email string, userTickets uint, remainingTickets uint) (bool, bool, bool) {
    isValidName := len(firstName) >= 2 && len(lastName) >= 2
    isValidEmail := strings.Contains(email, "@")
    isValidTicketNumber := userTickets > 0 && userTickets <=
        remainingTickets
    return isValidName, isValidEmail, isValidTicketNumber
}

func getUserInput() (string, string, string, uint) {

    var firstName string
    var lastName string
    var email string
    var userTickets uint

    fmt.Println("Enter your first name: ")
    fmt.Scan(&firstName)

    fmt.Println("Enter your last name: ")
    fmt.Scan(&lastName)

    fmt.Println("Enter your e-mail address: ")
    fmt.Scan(&email)

    fmt.Println("Enter number of tickets: ")
    fmt.Scan(&userTickets)

    return firstName, lastName, email, userTickets
}

func bookTicket(remainingTickets uint, userTickets uint, bookings []string, firstName string, lastName string, email string,
    conferenceName string) {
    remainingTickets = remainingTickets - userTickets
    bookings = append(bookings, firstName+" "+lastName)

    fmt.Printf("Thank you %v %v for booking %v tickets. You will receive a confirmation email at %v\n", firstName, lastName, userTickets, email)
    fmt.Printf("%v tickets remaining for the %v.\n", remainingTickets, conferenceName)
    fmt.Println(bookings)
}

当我用输入测试它时，名字没有按要求附加。 This is the tutorial I'm following.

这是终端：

Welcome to Go Conference booking application!

We have a total of 50 tickets and 50 are still available.

Get your tickets here to attend.

Enter your first name:

caio

Enter your last name: 

rodrigues

Enter your e-mail address: 

cc@cc.com

Enter number of tickets: 

3

Thank you caio rodrigues for booking 3 tickets. You will receive a 
confirmation email at cc@cc.com

47 tickets remaining for the Go Conference.

[caio rodrigues]

**The first name of our bookings are: []**

Enter your first name:

john

Enter your last name: 

smith

Enter your e-mail address: 

jj@jj.com

Enter number of tickets: 

5

Thank you john smith for booking 5 tickets. You will receive a 
confirmation email at jj@jj.com

45 tickets remaining for the Go Conference.

[john smith]

**The first name of our bookings are: []**

应该将名字附加到列表中。

Answer 1

与大多数其他主流语言不同，如果您不对变量的值执行某些操作，Go 不允许使用变量。因此，在测试代码中解决这个问题的方法是将值打印到控制台。在末尾添加这一行：

fmt.Println(bookings)

Answer 2

因此，我对代码进行了一些清理，现在它又可以正常工作了。

bookings 现在作为包级变量在 main 之外，并且可以正常工作。

package main

import (
    "fmt"
    "strings"
)

const conferenceTickets int = 50

var conferenceName = "Go Conference"
var remainingTickets uint = 50

var bookings = []string{}

bookTickets 调用现在是：

bookTicket(userTickets, firstName, lastName, email)

调用函数：

func bookTicket(userTickets uint, firstName string, lastName string, email string) {
    remainingTickets = remainingTickets - userTickets
    bookings = append(bookings, firstName+" "+lastName)

    fmt.Printf("Thank you %v %v for booking %v tickets. You will receive a confirmation email at %v\n", firstName, lastName, userTickets, email)
    fmt.Printf("%v tickets remaining for the %v.\n", remainingTickets, conferenceName)
}

谢谢大家。

从未使用过此预订值 (SA4006)

this value of bookings is never used (SA4006)

error-handling

append

go