Error handling intro -

nil is a predeclared identifier like true, false, len(), int32, float64 etc.
Since it is a predeclared identifier, it can be used anywhere without importing any package.
nil value means that the value is not initialized yet.

It is similar to following identifiers in other languages:

null    // JavaScript
None    // Python
null    // Java
nil     // Ruby

The zero value of all pointer-based types in Go is nil. Following are the pointer-based types in Go:
- pointers
- slices
- maps
- interfaces
- channels
In Go, nil value can be untyped or typed depending on the context.

Nil in error handling

In Go, nil value is extensively used for Error Handling.

For e.g.

func main() {
    data, err := someFunc()

    if err != nil {
        fmt.Println("Error occurred")
        return
    } else {
        fmt.Println("Success")
    }
}

Nil in error handling

See also