Golang : Accept input from user with fmt.Scanf skipped white spaces and how to fix it



Tags : golang accept-input scanf whitespace bufio-readstring

Problem :

Your program accepts user input from console(terminal). It was working fine if the user input is in one word, but not for words(i.e whitespaces in between). What is going on and how to fix it?

Solution :

According Golang's official documentation ( http://golang.org/pkg/fmt/#pkg-overview ). Under the Scanning section :

Scanln, Fscanln and Sscanln stop scanning at a newline and require that the items be followed by one;

Scanf, Fscanf and Sscanf require newlines in the input to match newlines in the format; the other routines treat newlines as spaces.

Chances are...that... your program is accepting user input with fmt.Scanf() function such as below :

 fmt.Print("Please enter your name ... ")
 fmt.Scanf("%s", &name)

and fmt.Scanf() function loves to get stopped by white spaces. To fix this problem, use bufio.NewReader() and bufio.ReadString() functions to read from standard input (os.Stdin).

For example :

 package main

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

 func main() {

 consoleReader := bufio.NewReader(os.Stdin)
 fmt.Print("Enter your name .... \n")

 input, _ := consoleReader.ReadString('\n')

 fmt.Println("Your name is : ", input)

 }

Sample output :

Enter your name ....

Boo Boo Baa

Your name is : Boo Boo Baa

Hope this tutorial can be useful to you. Happy coding!



Tags : golang accept-input scanf whitespace bufio-readstring

By Adam Ng

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