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57.go
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57.go
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/*
Exercise: Errors
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 (
// "errors"
// "fmt"
// "math"
// )
// func Sqrt(f float64) (float64, error) {
// if f < 0 {
// e := errors.New("cannot Sqrt negative number")
// return f, e
// }
// return math.Sqrt(f), nil
// }
// func main() {
// fmt.Println(Sqrt(2))
// fmt.Println(Sqrt(-2))
// }
package main
import (
"fmt"
"math"
)
type ErrNegativeSqrt float64
func (e ErrNegativeSqrt) Error() string {
return fmt.Sprint("cannot Sqrt negative number ", float64(e))
}
func Sqrt(f float64) (float64, error) {
if f < 0 {
return f, ErrNegativeSqrt(f)
}
return math.Sqrt(f), nil
}
func main() {
fmt.Println(Sqrt(2))
fmt.Println(Sqrt(-2))
}