CODEWITHSUNDEEP
go
New Sance
New Sance

Reputation: 93

Is there an idiomatic go way to print string pointer contents or nil?

I have a string pointer that may or may not be nil, and I want to print out either the contents of the string if contents exist, or indicate that the pointer is nil if it is nil. Is there a clever way to do this that doesn't involve either an if check or a temporary variable (preferably a single line)?

Right now I'm using something like this:

if p == nil {
    fmt.Print(p)
} else {
    fmt.Print(*p)
}

But this is particularly awkward and verbose when there is other formatting and other variables that are intended to be printed before and/or after that value.

Upvotes: 8

Views: 11268

Answers (1)

Franck Jeannin
Franck Jeannin

Reputation: 6844

You could do something like this: 

func main() {
    var hello SmartString = "hello"

    p := &hello
    p.Print()
    p = nil
    p.Print()

}

type SmartString string

func (p *SmartString) Print() {
    if p == nil {
        fmt.Println(p)
    } else {
        fmt.Println(*p)
    }
}

Whether it's a good idea or not is up to you.

You can even use the String interface to make it work with fmt.Println

func main() {
    var hello SmartString = "hello"

    p := &hello
    fmt.Println(p)
    p = nil
    fmt.Println(p)

}

type SmartString string

func (p *SmartString) String() string {
    if p == nil {
        return "<nil>"
    }
    return string(*p)
}

Upvotes: 7

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