Scanln in Golang doesn't accept whitespace

go, io, stdin, string

Solution

You can't use the `fmt` package's `Scanln()` and similar functions for what you want to do, because quoting from `fmt` package doc:

Input processed by verbs is implicitly space-delimited: the implementation of every verb except %c starts by discarding leading spaces from the remaining input, and the %s verb (and %v reading into a string) stops consuming input at the first space or newline character.

The `fmt` package intentionally filters out whitespaces, this is how it is implemented.

Instead use `bufio.Scanner` to read lines that might contain white spaces which you don't want to filter out. To read / scan from the standard input, create a new `bufio.Scanner` using the `bufio.NewScanner()` function, passing `os.Stdin`.

Example:

scanner := bufio.NewScanner(os.Stdin)
if scanner.Scan() {
    line := scanner.Text()
    fmt.Printf("Input was: %q\n", line)
}

Now if you enter 3 spaces and press Enter, the output will be:

Input was: "   "

A more complete example that keeps reading lines until you terminate the app or enter `"quit"`, and also checks if there was an error:

scanner := bufio.NewScanner(os.Stdin)
for scanner.Scan() {
    line := scanner.Text()
    fmt.Printf("Input was: %q\n", line)
    if line == "quit" {
        fmt.Println("Quitting...")
        break
    }
}
if err := scanner.Err(); err != nil {
    fmt.Println("Error encountered:", err)
}

Problem

Original source