Go programs express error state with error values.

The error type is a built-in interface similar to fmt.Stringer:

1type error interface {
2  Error() string
3}

functions often return an error value, and calling code should handle errors by testing whether the error equals to nil:

1i, err := strconv.Atoi("42")
2if err != nil {
3    fmt.Printf("couldn't convert number: %v\n", err)
4    return
5}
6fmt.Println("Converted integer:", i)

References

• interface-values-in-go
• stringers-interface-in-go