sizeof

Returns the total size, in bytes, of the input variable.

Prototype

	function sizeof (
		data       
	)

	return_val [1] :  integer or long

Arguments

A variable of any type or dimensionality.

Description

The sizeof function returns a value that is the size in bytes of the data pointed to by the parameter data.

In versions 6.0.0 or later, this function will return a long if on a 64-bit system and the value is greater than or equal to 2 gigabytes (GB).

To return the length of a string, don't use this function. Use strlen instead.

For variables like file pointers and graphical objects, this function is not very useful as it just returns the size of the pointer that points to the file or object.

See Also

strlen, dimsizes, typeof, new, default_fillvalue, set_default_fillvalue

Examples

The example below shows how sizeof works for different types and dimensionalities:

Example 1

  carray = new((/2,3/),character)
  sarray = new(5,short)
  iarray = new(1,integer)
  larray = new((/1,2/),long)
  farray = new((/2,3,4,5/),float)
  darray = new((/2,3,4,5/),double)

  print(sizeof(carray))       ; should be 6
  print(sizeof(sarray))       ; should be 10
  print(sizeof(iarray))       ; should be 4
  print(sizeof(larray))       ; should be 8 (or 16 on 64-bit machine)
  print(sizeof(farray))       ; should be 480
  print(sizeof(darray))       ; should be 960

;
; Variable types for which "sizeof" doesn't provide much information.
;
  f    = addfile("$NCARG_ROOT/lib/ncarg/data/cdf/Pstorm.cdf","r")
  plot = new(1,graphic)
  str  = "Comedy is not pretty"     ; quote by Steve Martin

  print(sizeof(f))      ; Should be 4 (or 8 on 64-bit machine)
  print(sizeof(plot))   ; Should be 4 (or 8 on 64-bit machine)
  print(sizeof(str))    ; Should be 4 (or 8 on 64-bit machine)

Example 2

Create an array that's larger than 2 GB. This will not work on a 32-bit system, or with versions 5.2.x or earlier:

  x =  new(tolong(2^29),float)    
  s = sizeof(x)
  print(s)

Output:

Variable: s
Type: long
Total Size: 8 bytes
            1 values
Number of Dimensions: 1
Dimensions and sizes:[1]
Coordinates: 
(0)   2147483648