Copy your Sqrt function from the earlier exercises and modify it to return an error value.
Sqrt should return a non-nil error value when given a negative number, as it doesn't support complex numbers.
Create a new type
type ErrNegativeSqrt float64
and make it an error by giving it a
func (e ErrNegativeSqrt) Error() string
method such that ErrNegativeSqrt(-2).Error() returns "cannot
Sqrt negative number: -2".
Note: a call to fmt.Print(e) inside the Error method
will send the program into an infinite loop. You can avoid this by converting e first:fmt.Print(float64(e)).
Why?
Change your Sqrt function to return an ErrNegativeSqrt value
when given a negative number.
package main
import (
"fmt"
)
type ErrNegativeSqrt float64
func (e ErrNegativeSqrt) Error() string{
return fmt.Sprintf("cantnot Sqrt negative number: %v", float64(e))
}
func Sqrt(f float64) (float64, error) {
if f < 0 {
return 0, ErrNegativeSqrt(f)
}
z := f
for i := 0; i < 10; i++ {
z = (z + f/z)/2
}
return z, nil
}
func main() {
if value, err := Sqrt(-2); err != nil {
fmt.Println(err)
} else {
fmt.Println(value)
}
if value, err := Sqrt(2); err != nil {
fmt.Println(err)
} else {
fmt.Println(value)
}
}