pointers.md

👉 Pointers

• 👉 Pointers
  • 👀 Fast Lookup
  • 📈 Extra notes

👀 Fast Lookup

• Pointer: Variable that stores memory address of another variable
• Address operator: &variable gets the address of a variable
• Dereference operator: *pointer gets the value at the address
• Declaration: var p *int declares a pointer to int
• Zero value: nil is the zero value of a pointer
• Memory efficiency: Pass large structs by pointer to avoid copying
• Modification: Pointers allow functions to modify original values
• Safety: Go doesn't allow pointer arithmetic (unlike C/C++)

Pointer is a variable that stores the memory address of another variable.

var a int = 10
var b *int = &a // b stores the memory address of a

fmt.Println(a) // 10
fmt.Println(b) // memory address of a
fmt.Println(*b) // 10

*b = 20 // change the value of a. Assign 20 to the place where b points to
fmt.Println(a) // 20

📈 Extra notes

• nil is a zero value of a pointer.

• Q: Why use pointers?

type Data struct {
  value int
  data [1000]float64
}

func DummyFunc1(data Data) {
  // When data is passed to the function, a copy of the data is created.
}

func DummyFunc2(data *Data) {
  // When pointer is passed to the function, the original data is passed.
  // Which means the function can modify the original data.
  // Also means the Data is not copied to the function. 
}