What is the difference between interface and struct in Go?

Question

Accepted Answer

**Interface** — behavior (methods). **Struct** — data structure.

**Interface:**
- Method signatures only.
- No data fields.
- Implicit implementation.
- Can be empty (any type).

```go
// Interface
type Speaker interface {
    Speak() string
}

// Any type with Speak() implements Speaker
type Dog struct { Name string }

func (d Dog) Speak() string {
    return "Woof"
}
```

**Struct:**
- Data fields.
- Can have methods.
- Value type.

```go
// Struct
type Person struct {
    Name string
    Age  int
}

// Method
func (p Person) Greet() {
    fmt.Println("Hello")
}
```

**Empty interface:**
```go
// Accepts any type
func PrintAnything(v interface{}) {
    fmt.Println(v)
}
```

Go: What is the difference between interface and struct in Go?