tour: unclear instruction for errors exercise #273
Description
Context: https://tour.golang.org/methods/20
The instruction does not clearly define what to do.
I was expecting an output:
1.41
cannot Sqrt negative number: -2
while the only output I was able to produce is
1.41 <nil>
0 cannot Sqrt negative number: -2
as fmt.Println(Sqrt(2)) will print "error"
and fmt.Println(Sqrt(-2)) will print the float64 part
It should be also noted earlier that %g is the way to print float64
My code:
type ErrNegativeSqrt float64
func (e ErrNegativeSqrt) Error() string {
return fmt.Sprintf("cannot Sqrt negative number: %g", float64(e))
}
func (e ErrNegativeSqrt) String() string {
return fmt.Sprintf("%f",e)
}
func Sqrt(x float64) /*ErrNegativeSqrt*/(float64, error) {
if x<0 {
return 0,ErrNegativeSqrt(x) // Why do I need to include 0? nil seems more appropriate
}
var z1, z2 float64 = 1,0
for i:=0; i<8; i++ {
z2 = z1-((z1*z1-x)/(2*z1))
z1=z2
}
return z2, nil
}