02-learning-golang-pointers-2025-09-12

References

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Introduction

The next segment is about pointers. I wonder if these are similar to C?

At first glance, it looks similar.

Here is how to define a pointer,

var p *int

The * syntax defines a pointer.

And the & operator generates a pointer to its operand,

myString := "hello"
myStringPtr := &myString

We can use the * operator to dereference a pointer to get back its original value.

*myStringPtr = "world"                              // set myString through the pointer
fmt.Printf("value of myString: %s\n", *myStringPtr) // read myString through the pointer
// value of myString: world

Am not sure what this means yet - but the course says “Unlike C, Go has no pointer arithmetic”.

I do not understand this part about pointers to structs. i.e. the following is invalid,

msgTotal := *analytics.MessagesTotal

Instead one of these might be fine?

msgTotal := analytics.MessagesTotal
(*analytics).MessagesTotal

What bothers me, is that the first one - does not look to be using pointers at all!

Something I forgot about functions in golang is the concept of function receivers. Due to the lack of OOP - they are the way to attach methods to structs. There are two ways to make the association - by using pointer receivers and by using non-pointer receivers.

Here is the example of how to use a pointer receiver,

type car struct {
	color string
}
 
func (c *car) setColor(color string) {
	c.color = color
}
 
func main() {
	c := car{
		color: "white",
	}
	c.setColor("blue")
	fmt.Println(c.color)
	// prints "blue"
}

And here is how to use a non-function receiver,

type car struct {
	color string
}
 
func (c car) setColor(color string) {
	c.color = color
}
 
func main() {
	c := car{
		color: "white",
	}
	c.setColor("blue")
	fmt.Println(c.color)
	// prints "white"
}

Both of them have access to the original struct. But it’s only using the pointer receiver can you mutate the value of the struct.