COBOL12 Compiler

DATES

Date is a specific data type. A date field is four bytes long and is comprised of four one-byte binary values for the century, year, month and day, in that sequence. Date fields will therefore provide correct date sequence when used as file or table keys.

The external format of a date is the format in which a date is displayed, the format of a literal date in the source program, and the format in which a date is input to the compiled program. It is specified by an optional clause in the Special-names paragraph.

ENVIRONMENT DIVISION.
SPECIAL-NAMES.
   [ DATE IS |"S-"|"E-"|"A-"| ]

where:  S   Sequential:  ccyy-mm-dd
        E   European:    dd-mm-ccyy
        A   American:    mm-dd-ccyy
         -  any character except a space or a digit.

The default format is "S-".

A literal value in the source program or a value input on the screen to a compiled program may have both the day and the month zero suppressed. In addition, if the century is omitted, the century of the current system date is used instead.

A date field is defined in the Data Division as follows.

DATA DIVISION.
lvl-no  dataname [USAGE IS] DATE 
        [ VALUE IS |date-lit|ZERO ] .

A date is always stored in a four character field; the PIC X(4) is not necessary in the definition. A null date is defined as ZERO, is stored as a LOW-VALUES field, and is displayed by the program as spaces.

A literal date must be enclosed in quotes.

PROCEDURE DIVISION.

The following special actions are available in the Procedure Division with date fields.

MOVE date-item TO numeric-item

The numeric item will be set to the day of the week, 1 to 7 representing Sunday to Saturday respectively, with zero representing a null date.

MOVE date-item TO display-item

Converts the date to the defined external format in the display-item.

MOVE display-item TO date-item

De-edits the display-item and stores the derived date in the date-item. If display-item does not contain a valid date, date-item is set to low-values.

ADD number TO date-item

Adds a number of days to the date.

SUBTRACT number FROM date-item

Subtracts a number of days from the date.

SUBTRACT date-item-1 FROM date-item-2 GIVING binary-item

Calculates the difference in days between the two dates and stores the result in binary-item, which must be defined as a binary integer item.

ADD and SUBTRACT statements are valid only for dates from 1901 to 2099 inclusive. Any other date will return a date or a value of zero.

Date Validation
There is no specific statement to validate a date. However, adding a number to a date always returns a valid date regardless of the validity of the original date. Thus, a date may be validated conveniently with the following method:

  MOVE ZERO TO null-count
  MOVE date-to-validate TO check-date
  ADD null-count TO check-date
  IF check-date NOT = date-to-validate
     GO TO date-error
  .