> For the complete documentation index, see [llms.txt](https://zeyad-abulaban.gitbook.io/notes/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://zeyad-abulaban.gitbook.io/notes/golang-programming/pointers.md).

# Pointers

***

## Basic Syntax

```go
package main

import "fmt"

func main() {
	var a int = 42
	var b *int = &a //Points to "a" address.
	fmt.Println(&a,b)
}
```

## Derefrencing

```go
package main

import "fmt"

func main() {
	var a int = 42
	var b *int = &a //Points to "a" address.
	fmt.Println(a,*b) // Makes the complier find the value stored in memmory annd displayes it.
}
```

**Examples**

```go
package main

import "fmt"

func main() {
	var a int = 42
	var b *int = &a //Points to "a" address.
	*b = 15
	fmt.Println(a,*b) //Prints 15
}
```

```go
package main

import "fmt"

func main() {
	a := [3]int{1,2,3}
	b := &a[0]
	c := &a[1]
	fmt.Printf("%v %p %p\n",a,b,c)
}
```

**Pointers arthmetic isn't available in go** The following code will produce an error:

```go
package main

import "fmt"

func main() {
	a := [3]int{1,2,3}
	b := &a[0]
	c := &a[1] - 4
	fmt.Printf("%v %p %p\n",a,b,c)
}
```

> Note: You can use `unsafe` package

## Pointers with structs

The output is like saying: "`ms` is holding the address of an object that has a field of `value 42` in it "

```go
package main

import "fmt"

func main() {
	var ms *myStruct
	ms = &myStruct{foo:42}
	fmt.Println(ms)
}

type myStruct struct{
	foo int
}
```

**With an empty object**

```go
package main

import "fmt"

func main() {
	var ms *myStruct
	ms = new(myStruct)
	fmt.Println(ms)
}

type myStruct struct{
	foo int
}
```

## *nil*

```go
package main

import "fmt"

func main() {
	var ms *myStruct
	fmt.Println(ms) // Because the ms Points to Null
	ms = &myStruct{foo:42}
	fmt.Println(ms)
}

type myStruct struct{
	foo int
}
```

**Assigning a value**

```go
package main

import "fmt"

func main() {
	var ms *myStruct
	ms = new(myStruct)
	(*ms).foo = 42
	fmt.Println((*ms).foo)
}

type myStruct struct{
	foo int
}
```

**Compiler can help us :)**

```go
package main

import "fmt"

func main() {
	var ms *myStruct
	ms = new(myStruct)
	ms.foo = 42
	fmt.Println(ms.foo)
}

type myStruct struct{
	foo int
}
```


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