From https://code.google.com/p/go/issues/detail?id=5391

fmt.scanf()函数的bug

 package main

    import "fmt"

    func main() {
        min, max := 0, 100
        fmt.Printf("%d--%d", min, max)
        for min < max  {
            i := (min + max) / 2
            fmt.Printf("<=%d(y or n)  ", i)
            var s string
            fmt.Scanf("%s", &s)
            if s != "" && s[0] == 'y' {
                max = i
            } else {
                min = i + 1
            }
        }
        fmt.Printf("%d\n", max)
    }