What is the difference between error and exception?

Question

Accepted Answer

**error** — Go interface for expected failures. **Exception** — not in Go (use panic/recover).

**Error interface:**
```go
type error interface {
    Error() string
}
```

**Creating errors:**
```go
var ErrNotFound = errors.New("not found")

type ValidationError struct {
    Field, Message string
}

func (e *ValidationError) Error() string {
    return fmt.Sprintf("%s: %s", e.Field, e.Message)
}

func load(path string) (*Config, error) {
    data, err := os.ReadFile(path)
    if err != nil {
        return nil, fmt.Errorf("loading %s: %w", path, err)
    }
    // ...
}
```

**Error handling:**
```go
if errors.Is(err, ErrNotFound) {
    // handle
}

var valErr *ValidationError
if errors.As(err, &valErr) {
    fmt.Println(valErr.Field)
}
```

**Go philosophy:**
- "Errors are values."
- Explicit handling.

**Common mistakes:**
- Ignoring errors.
- Not wrapping errors.
- Using `==` instead of `errors.Is()`.
- Creating error strings with capitals.
- Overusing panic.

Go: What is the difference between error and exception?