Cobol dashes are confusing me [duplicate]

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cobol difference with Picture having a dash (-) and a having a X

I'm tying to get to grips with Cobol and can't understand the dashes when formatting a number. I have this example:

--9

Am I correct with the following?

The first dash - If number is a negative put a dash otherwise don't.

the second dash - I'm confused with this. There is already a dash at the start to specify whether its neg开发者_开发百科ative or positive.

9 - Numeric digit (0-9)

An example would be good. :S

Thanks

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In view of your previous question, Im not sure what you are having trouble with. But lets try again...

In COBOL, numeric display fields may contain various types of "punctuation". This "punctuation" is defined in the items PICTURE clause. A few examples of the type of "punctuation" symbols you can use are: Explicit decimal points, plus/minus signs, CR/DR indicators and thousnads separators (commas in North America). There is a well defined set of rules that determine what type of "punctuation" can occur in the PICTURE clause and where. This link to PICTURE CLAUSE editing explains how to construct (or read) any given PICTURE clause.

One thing that you, and many others new to COBOL, trip up on is that a data definition in COBOL specifies two distinctly different types of information about numeric display data. One is the range of values it may hold and the other is how that range of values may be displayed. Your example: PICTURE --9 tells me two things about the data item: 1) Values are integers in the range of -99 through to +99, and 2) Displaying this item will take 3 spaces. If the number is positive, spaces will appear before the first non zero digit. If the number is negative a minus sign will appear immediately to the left of the first non zero digit. Consider the following COBOL DISPLAY statement:

 DISPLAY '>' DISP-NBR '<'

IF DISP-NBR has a PICTURE clause of: --9 this is how various values will be displayed.

  0 displays as: >  0<
 -1 displays as: > -1<
-11 displays as: >-11<
 10 displays as: > 10<

Note that all displays take 3 character positions. At least 1 digit will always be displayed (because of the '9' in the PICTURE clause), other than that, no leading zeros are displayed. A minus sign will display only for negative values. The minus sign, if displayed will be to the immediate left of the first displayed digit.

Now to answer you specific question: The total number of character positions needed to display a numeric display data item is determined by the length of the PICTURE. You have a 3 character PICTURE so 3 character positions are needed. When a sign is specified in the PICTURE, a space is always reserved for it. This is what limits the range of integers to those containing at most 2 digits. The second minus sign indicates 'zero supression'. Zero supression just means not printing leading zeros. Only 1 minus sign is ever printed and it will be to the immediate left of the first displayed digit.

COBOL contains a lot of flexability with respect to displaying numbers. Understanding the numeric display PICTURE clause is key to understanding how this all works.

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from stackoverflow:cobol-difference-with-picture-having-a-dash-and-a-having-a-x

The dash means that if you have a negative number, a dash will be shown beside (at the left) of the number. Only one dash will be displayed. If the number is positive, a space will shown for every dashes.