从stdin读取到int的字符串的类型转换给我0

Question

Code:

reader := bufio.NewReader(os.Stdin)
fmt.Print("Enter a number")
input,_ := reader.ReadString('
')
fmt.Printf("Type of the entered value is %T
",input)
fmt.Println(input)
out,_ := strconv.Atoi(input)
fmt.Printf("Type now is: %T
", out)
fmt.Printf("Value now is %d
",out)
fmt.Println(out)

Complete beginner to Golang. I was trying to solve one of the problems from r/dailyprogrammer. I took the snippet to read the input from SO, as well as the strconv.Atoi function. The examples for this function make sense but when I apply it to the input I read from stdin, it gives me 0.

Answer 1

If you change your code a little you'll see that strconv.Atoi(input) is returning an error. I hope you've now learned an important lesson about how Go does error handling.

Error is: strconv.Atoi: parsing "1 ": invalid syntax

out, err := strconv.Atoi(input)
if err != nil {
    fmt.Printf("Error is: %v
", err)
}

One way to fix this is by trimming input using strings.TrimSuffix():

reader := bufio.NewReader(os.Stdin)
fmt.Print("Enter a number")
input, _ := reader.ReadString('
')
input = strings.TrimSuffix(input, "
")
fmt.Printf("Type of the entered value is %T
", input)
fmt.Println(input)
out, err := strconv.Atoi(input)
if err != nil {
    fmt.Printf("Error is: %v
", err)
}
fmt.Printf("Type now is: %T
", out)
fmt.Printf("Value now is %d
", out)
fmt.Println(out)

You can also use the Scanner, which doesn't require you to remove the :

scanner := bufio.NewScanner(os.Stdin)
fmt.Print("Enter a number")
scanner.Scan()
input := scanner.Text()