Challenge 1 — Solution

Task: Write a function divide(a, b float64) (float64, error) that
returns an error from the errors package if b is 0, otherwise the
division result and nil. Call it twice — once with b = 0, once with
a real divisor — handling both with if err != nil.

package main

import (
	"errors"
	"fmt"
)

func divide(a, b float64) (float64, error) {
	if b == 0 {
		return 0, errors.New("cannot divide by zero")
	}
	return a / b, nil
}

func main() {
	result, err := divide(10, 0)
	if err != nil {
		fmt.Println("Error:", err)
	} else {
		fmt.Println("Result:", result)
	}

	result, err = divide(10, 2)
	if err != nil {
		fmt.Println("Error:", err)
	} else {
		fmt.Println("Result:", result)
	}
}


Expected output:

Error: cannot divide by zero
Result: 5

Notes:
- The second call reuses result and err with = instead of := since
  both variables already exist from the first call.
- errors.New("...") creates a real error value; printing it with
  fmt.Println shows just the message text.
- divide(10, 2) returns nil as its error, so the if err != nil check
  correctly falls through to printing the result instead.