Pointers is an actively used design pattern created in 1964. A pointer is a programming language object that stores the memory address of another value located in computer memory.

55Years Old

Languages without Pointers include javascript

Languages with Pointers include ada, blitzmax, c, cobol, csharp, d, eiffel, felix, fortran-90, freebasic, go, pl-i

Example from c:

int *ptr;

Example from csharp:

// Pointers supported only under certain conditions.
// Get 16 bytes of memory from the process's unmanaged memory
IntPtr pointer = System.Runtime.InteropServices.Marshal.AllocHGlobal(16);

Example from felix:

var x = 1;
&x <- 2;

Example from fortran-90:

type real_list_t
  real :: sample_data(100)
  type (real_list_t), pointer :: next => null ()
end type

type (real_list_t), target :: my_real_list
type (real_list_t), pointer :: real_list_temp

real_list_temp => my_real_list
do
  read (1,iostat=ioerr) real_list_temp%sample_data
  if (ioerr /= 0) exit
  allocate (real_list_temp%next)
  real_list_temp => real_list_temp%next
end do

Example from go:

package main

import "fmt"

func main() {
  i, j := 42, 2701

  p := &i         // point to i
  fmt.Println(*p) // read i through the pointer
  *p = 21         // set i through the pointer
  fmt.Println(i)  // see the new value of i

  p = &j         // point to j
  *p = *p / 37   // divide j through the pointer
  fmt.Println(j) // see the new value of j
}

Last updated June 22nd, 2020

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