Length of Arrays in SML

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2 total messages Started by Susan E Smith Tue, 05 Jan 1993 19:49

#1056

Author: Susan E Smith
Date: Tue, 05 Jan 1993 19:49

29 lines
1656 bytes

PROBLEM:  I am using Standard ML (New Jersey), Version 0.66 and I am trying
to use the Array function "length" to get the length of an array.  I have
defined my array using arrayoflist:

	eg.	val My_Array = arrayoflist ["Hi","My","Name","Is","Bob"];

	Now I want to use "length My_Array" to return the integer 5.

The reference manual I am using, says that this can be done and that the
function length is one that takes an array and returns an int.

However, this gives me an error when I try it in my version of SML and when
I type "length;" it tells me that length accepts a list and returns an int,

	eg.	length My_List;  returns the length of the list, My_List.

	I have tested this and this is the case.

The discrepancy between my reference manual and my version of SML is not the
major concern here, what I really want to know is:  Is there a way to get
the length of an array in the version of SML I am using.  This is important
to my application because I have a statement that says My_Array sub i where
i is begin incremented; hence, once i is out of range for the array, I don't
want the function to continue executing.

Any help would be greatly appreciated.

Susan
ssmith@ug.cs.dal.ca

Re: Length of Arrays in SML

#1057

Author: Andrew Koenig
Date: Wed, 06 Jan 1993 09:28

16 lines
990 bytes

In article <C0ECE1.Ju@cs.dal.ca> ssmith@ug.cs.dal.ca (Susan E Smith) writes:

> PROBLEM:  I am using Standard ML (New Jersey), Version 0.66 and I am trying
> to use the Array function "length" to get the length of an array.

The problem is that the built-in function "length" takes a list,
as you found out.  What you want is the "length" in the Array
structure, which is therefore called Array.length:

	val My_Array = arrayoflist ["Hi","My","Name","Is","Bob"];
	Array.length My_Array;

should print 5.
-- 
				--Andrew Koenig
				  ark@europa.att.com

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