What is the difference between := and = in Go?

Question

Accepted Answer

**:=** — declare and initialize. **=** — assign.

```go
// := — short variable declaration
x := 42  // Declares x and assigns 42

// = — assignment
x = 100  // Assigns new value to x

// var — explicit declaration
var y int = 10
```

**Rules for :=:**
- Only inside functions.
- At least one new variable.
- Cannot redeclare in same scope.

```go
func main() {
    x := 1
    x := 2  // Error! x already declared

x, y := 1, 2  // OK — y is new
    x, y = 3, 4   // OK — assignment
}
```

- **:=** — declare new variable.
- **=** — assign to existing.

Go: What is the difference between := and = in Go?