CODEWITHSUNDEEP
go
Dac0d3r
Dac0d3r

Reputation: 1844

How to "cast" a pointer back to a value in Golang?

I'm using time.Time as a pointer in one of my structs. Eg

type struct Example{
    CreatedDate *time.Time
}

I'm using the pointer, so I can pass nil to the struct, if no date exists.

This does however pose a problem now, since I need to use the time.Since(then) function which does not accept the pointer as the parameter, but takes a time.Time instead.

So...

It's quite easy to put "&" in front of a struct eg. &time.Time, but if you have a pointer, how can you reverse it, back into eg. a type of time.Time?

Eg. (does not work, but might give you an idea of what I mean)

var t *time.Time = &time.Now()
var t2 time.Time = t.(time.Time)

I hope you can help. The question feels quite silly, since I can't find anything about it when googling. I get the feeling I'm just missing something here ;-)

Upvotes: 54

Views: 56076

Answers (1)

Not_a_Golfer
Not_a_Golfer

Reputation: 49187

var t *time.Time = &time.Now()
var t2 time.Time = *t

Just like in C, & means "address of" and assigns a pointer which is marked as *T. But * also means "value of", or dereferencing the pointer, and assigns the value.

This is a bit off-topic, but IMO this dual use of * is partly what gets newbies in C and friends confused about pointers.

Upvotes: 104

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