Generating new instance of struct from scanner input

Question

I was attempting to run a program that created a new instance of a predefined struct from the users input.
The struct is comprised of 3 fields type string. The goal being for the user to input strings into a scanner, creating a new, unique instance of the struct, using the input as it's values. The program would be in a loop, allowing the user to create multiple instances of the struct.
In the code presented, there are 2 struct types; Boat and Car. The first string input would indicate which type of struct is chosen to be created, and the next 3 strings would be to fill the struct values.

package main

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

type Boat struct {
   name string
   color string
   design string
}
type Car struct {
   name string
   color string
   design string
}

func main() {

    TempBoat := Boat{"gerrard","red","speed"}
    TempCar := Car{"conroy","blue","cruiser"}

        /* I was using a template that would then be filled by the user, but 
          this only allows for one instance that would continue to be 
          overwritten. */

    scanner := bufio.NewScanner(os.Stdin)
    for {
        if scanner.Scan() {
            userIn := scanner.Text()
            scanMain := strings.Fields(userIn)
            Scan0 := scanMain[0]
            Scan1 := scanMain[1]
            Scan2 := scanMain[2]
            Scan3 := scanMain[3]
            if Scan0 == "car" {
                TempCar.name = Scan1
                TempCar.color = Scan2
                TempCar.design = Scan3
            } else if Scan0 == "boat" {
                TempBoat.name = Scan1
                TempBoat.name = Scan2
                TempBoat.name = Scan3
            } else {
                fmt.Println("Invalid Input. Try Again.")
            }
        }
    }
}

To create a unique value on each iteration, move the `TempBoat` and `TempCar` declarations to the inside the loop. What is it that you want to do with those values? — Charlie Tumahai, Oct 28 '22 at 18:14
than you @Cerise Limón. I am attempting to implement those changes now. — CodeDragon, Oct 28 '22 at 18:17
I would like those values to be added to the struct, as a unique variable of type Car or Boat. — CodeDragon, Oct 28 '22 at 18:21
You seem to be lacking `slice = append(slice, value)`. You should take the Go Tour to learn the basics. — mkopriva, Oct 28 '22 at 18:23
Is your actual question "How do I collect a boat or car created on each iteration of the loop?" — Charlie Tumahai, Oct 28 '22 at 18:37
Yes Cerise, I apologize for any confusion. SHA2048 had suggested creating a slice of structs and appending the struct on each iteration of the loop. I had no considered using a slice to store the input data. — CodeDragon, Oct 28 '22 at 18:42

score 3 · Accepted Answer · answered Oct 28 '22 at 18:27

You didn't really specify what you wanted to do with the values being read so i just put them into a slice for safe keeping.

package main

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

type Boat struct {
    name   string
    color  string
    design string
}
type Car struct {
    name   string
    color  string
    design string
}

func main() {

    var Boats = []Boat{}
    var Cars = []Car{}

    scanner := bufio.NewScanner(os.Stdin)
    for scanner.Scan() {
        userIn := scanner.Text()
        scanMain := strings.Fields(userIn)
        if len(scanMain) == 0 {
            break
        }
        if len(scanMain) != 4 {
            fmt.Println("Invalid Input. Try Again.")
        }
        Scan0 := scanMain[0]
        Scan1 := scanMain[1]
        Scan2 := scanMain[2]
        Scan3 := scanMain[3]
        if Scan0 == "car" {
            Cars = append(Cars, Car{Scan1, Scan2, Scan3})
        } else if Scan0 == "boat" {
            Boats = append(Boats, Boat{Scan1, Scan2, Scan3})
        } else {
            fmt.Println("Invalid Input. Try Again.")
        }
    }
    fmt.Println("Boats:", Boats)
    fmt.Println("Cars:", Cars)
}

Thank you SHA2048! I hadn't considered creating a slice of structs to store each individual instance, that was the piece of the puzzle I was missing. Your coding assistance is very much appreciated. /salute — CodeDragon, Oct 28 '22 at 18:32

Generating new instance of struct from scanner input

1 Answers1