scan.go

f, err := os.Open("salary.txt")
if err != nil {
	log.Fatal(err)
}
defer f.Close()

var xs []float64
scan := bufio.NewScanner(f)
for scan.Scan() {
	var v float64
	txt := scan.Text()
	_, err := fmt.Sscanf(txt, "%f", &v)
	if err != nil {
		log.Fatalf("could not convert to float64 %q: %v", txt, err)
	}
	xs = append(xs, v)
}

// make sure scanning the file and extracting values
// went fine without any error
if err = scan.Err(); err != nil {
	log.Fatalf("error scanning file: %v", err)
}