Why doesn't fmt.Scanf in Go wait for user input?

I am working through Caleb Doxsey's Go book and I have two questions about fmt.Scanf http://www.golang-book.com/4

I am wondering why the program does not stop after the second Scanf and wait for user input? And how do I test if the user entered an integer and/or did not leave blank?

package main

import (
"fmt"
//"math"
)


// compute square roots by using Newton's method

func main() {

var x float64		 	//number to take square root
var y float64			//this is the guess
var q float64			//this is the quotient
var a float64			//this is the average


// how do check if the user entered a number
fmt.Print("Enter a number to take its square root: ")
var inputSquare float64
fmt.Scanf("%f", &inputSquare)

// why doesn't program stop after 
// the Print statement and wait
// for user input?
fmt.Print("Enter first guess ")
var inputGuess float64
fmt.Scanf("%f", &inputGuess)

//x = 2
x = inputSquare
y = inputGuess

for i := 0; i < 10; i++ {	//set up the for loop for iterations
	q = x/y					//compute the quotient; x and y are given
	a = (q + y) / x			//compute the average		
	y = a					//set the guess to the average				
}							//for the next loop


fmt.Println("y --> ", y)
//fmt.Println("Sqrt(2)", math.Sqrt(2))
}

Update: was fixed almost a decade ago. The docs for fmt now read

> In all the scanning functions, a carriage return followed immediately by a newline is treated as a plain newline (\r\n means the same as \n).

If you continue to have scanning errors, mind that it isn't your IDE's fault.

It's Issue 5391: fmt: Scanf rejects \r\n at end of line on Windows.

As a workaround and to check for valid input, write,

var inputSquare float64
n, err := fmt.Scanf("%f\n", &inputSquare)
if err != nil || n != 1 {
	// handle invalid input
	fmt.Println(n, err)
}

and

var inputGuess float64
n, err = fmt.Scanf("%f\n", &inputGuess)
if err != nil || n != 1 {
	// handle invalid input
	fmt.Println(n, err)
}

The workaround is the newline in the "%f\n" format strings.

> Package fmt
>
> func Scanf
>
> func Scanf(format string, a ...interface{}) (n int, err error)
>
> Scanf scans text read from standard input, storing successive
> space-separated values into successive arguments as determined by the
> format. It returns the number of items successfully scanned.

Here's a complete working program:

package main

import (
	"fmt"
)

// compute square roots by using Newton's method
func main() {
	var x float64 //number to take square root
	var y float64 //this is the guess
	var q float64 //this is the quotient
	var a float64 //this is the average

	fmt.Print("Enter a number to take its square root: ")
	var inputSquare float64
	n, err := fmt.Scanf("%f\n", &inputSquare)
	if err != nil || n != 1 {
		// handle invalid input
		fmt.Println(n, err)
		return
	}

	fmt.Print("Enter first guess ")
	var inputGuess float64
	n, err = fmt.Scanf("%f\n", &inputGuess)
	if err != nil || n != 1 {
		// handle invalid input
		fmt.Println(n, err)
		return
	}

	x = inputSquare
	y = inputGuess
	for i := 0; i < 10; i++ {
		q = x / y       // compute the quotient; x and y are given
		a = (q + y) / x // compute the average
		y = a           // set the guess to the average
	}
	fmt.Printf("sqrt(%g) = %g\n", x, y)
}

Output:

Enter a number to take its square root: 2.0
Enter first guess 1.0
sqrt(2) = 1.414213562373095

I used Go 1.1.1 on Windows 7:

C:\>go version
go version go1.1.1 windows/amd64