Yes there is...-10 is a number and an operator, while "-10" is just a
string that happens to be a negative number.
Rick
On Mon, May 14, 2018 at 5:20 PM, Leslie Turriff <[email protected]> wrote:
> There seems to be a difference between -10 and "-10", though. :-)
>
> On 2018-05-14 15:43:59 Rick McGuire wrote:
> > The Rexx language has no such distinctions. Strings are strings, numbers
> > are strings that match the definition of a Rexx number. I wrote the
> code, I
> > do know how it works. There is absolutely no difference between
> >
> > a = 10
> >
> > and
> >
> > a = '10'
> >
> > The both produce the same result (although there's some hidden
> optimization
> > going on under the covers that is hidden from the programmer). The choice
> > of quoting the value or not is exactly that...a choice.
> >
> > Rick
> >
> > On Mon, May 14, 2018 at 1:41 PM, CV Bruce <[email protected]> wrote:
> > > It’s pretty clear that in all your test cases, the data is being
> treated
> > > as text.
> > >
> > > If the cases where the data is in the format of “testxx” it will always
> > > be treated as a text string. Specifying just that portion of the
> variable
> > > that is numeric doesn’t override that.
> > >
> > > In the case where you array contains just numbers, when you created the
> > > array you quoted all the numbers you assigned to the array thereby
> > > telling Rexx that you wanted those values treated as text strings.
> > >
> > > Bottom line, just because something looks like a number doesn’t mean
> that
> > > Rexx has the context to treat it as a number. For example if a
> variable
> > > looks like a number and then has an arithmetic operation performed on
> it,
> > > Rexx has enough context to treat the variable as a number.
> > > X='-2' <— text string
> > > X=X+0 <— Ok, it’s now a number.
> > > X=-2 <— Number
> > > X=X||” ” <— Ok, you want a text string
> > >
> > > As to:
> > > > For all the other comparison operators, if both terms are numeric,
> the
> > >
> > > String
> > >
> > > > class does a numeric comparison (ignoring, for example, leading zeros
> > >
> > > Rexx doesn’t know that it is a number until you tell it, it is a
> number.
> > > You loaded the array with text strings, and didn’t tell it otherwise so
> > > it compared them as text strings.
> > >
> > > Bruce
> > >
> > > > On May 14, 2018, at 9:59 AM, Leslie Turriff <[email protected]>
> wrote:
> > > >
> > > > I need to sort an array of strings by their signed numeric
> > >
> > > suffixes, but I'm
> > >
> > > > getting some strange results from sort and sortWith. I have attached
> > > > my
> > >
> > > V4.2
> > >
> > > > test program; together with its output.
> > > >
> > > > Section 5.1.3.8 of the Language Reference says,
> > > > 'The strict comparison operators do not attempt to perform a numeric
> > > > comparison on the two operands.
> > > > For all the other comparison operators, if both terms are numeric,
> the
> > >
> > > String
> > >
> > > > class does a numeric comparison (ignoring, for example, leading
> zeros—
> > >
> > > see
> > >
> > > > Section 10.4, “Numeric Comparisons”).'
> > > >
> > > > Section 10.4 says,
> > > > 'Numeric values are compared by subtracting the two numbers
> > > > (calculating
> > >
> > > the
> > >
> > > > difference) and then comparing the result with 0. That is, the
> > > > operation: A ? Z
> > > > where ? is any numeric comparison operator, is identical with:
> > > > (A - Z) ? "0"
> > > > It is, therefore, the difference between two numbers, when subtracted
> > >
> > > under
> > >
> > > > Rexx subtraction rules, that determines their equality.'
> > > >
> > > > Further, Section 10 says,
> > > > 'Numbers can be expressed flexibly. Leading and trailing whitespace
> > >
> > > characters
> > >
> > > > are permitted, and
> > > > exponential notation can be used. Valid numbers are, for example:
> > > >
> > > > Example 10.1. Numbers
> > > >
> > > > 12 /* a whole number */
> > > > "-76" /* a signed whole number */
> > > > 12.76 /* decimal places */
> > > > " + 0.003 " /* blanks around the sign and so forth */
> > > > 17. /* same as 17 */
> > > > .5 /* same as 0.5 */
> > > > 4E9 /* exponential notation */
> > > > 0.73e-7 /* exponential notation */
> > > >
> > > > A number in Rexx is defined as follows:
> > > >>> -+------------+--+----------------------+--+-digits--------+
> > >
> > > ---------->
> > >
> > > > +-whitespace-+ +-sign--+------------+-+ +-digits.digits-+
> > > > +-whitespace-+ +-.digits-------+
> > > > +-digits.-------+
> > > >
> > > >> --+------------+--------------------------------------------
> ------><
> > > >
> > > > +-whitespace-+
> > > >
> > > > whitespace
> > > > are one or more blanks or horizontal tab characters.
> > > > sign
> > > > is either + or -.
> > > > digits
> > > > are one or more of the decimal digits 0-9.'
> > > >
> > > > However, in section 5.3.18, Sorting Arrays, we see that
> > > > 'The sort method orders the strings by using the compareTo method of
> > > > the String class. The compareTo method knows how to compare one
> string
> > > > to another, and returns the values -1 (less than), 0 (equal), or 1
> > > > (greater than) to indicate the relative ordering of the two strings.'
> > > >
> > > > and
> > > > 'Performs a sort comparison of the target string to the string
> > > > argument.
> > >
> > > If
> > >
> > > > the two strings are equal, 0 is returned. If the target string is
> > >
> > > larger, 1
> > >
> > > > is returned. -1 if the string argument is the larger string.
> > > > The comparison is performed starting at character n for length
> > >
> > > characters in
> > >
> > > > both strings. n must be a positive whole number. If n is omitted, the
> > > > comparison starts at the first character. length must be a
> non-negative
> > >
> > > whole
> > >
> > > > number. If omitted, the comparison will take place to the end of the
> > >
> > > target
> > >
> > > > string.'
> > > >
> > > > which seems to imply a character comparison; and the examples for
> > >
> > > compareTo
> > >
> > > > include no numeric strings.
> > > >
> > > > Looking at the output from the test program, ooRexx seems to be
> > >
> > > sorting
> > >
> > > > signed numeric strings non-numerically (+ < - < 0), contrary to what
> > >
> > > would be
> > >
> > > > expected from section 10. This seems to me to be a bug? I would not
> > >
> > > expect
> > >
> > > > to have to write a custom comparator to re-implement a built-in
> > >
> > > mechanism.
> > >
> > > > Leslie
> > > >
> > > >
> > > >
> > > > <testSort.txt><testSort.txt>--------------------------------
> > >
> > > ----------------------------------------------
> > >
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> > >
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> > >
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>
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