COBOL Date-Time Functions

COBOL provides intrinsic functions for date and time: getting the current date and time (CURRENT-DATE), converting between dates and integers for arithmetic (INTEGER-OF-DATE, DATE-OF-INTEGER), and related functions. These help you avoid hand-written date logic for month boundaries and leap years. This page explains the main date-time functions and how to use them.

Explain Like I'm Five: Date-Time Functions

Date-time functions are helpers that answer questions like "what is today?" (CURRENT-DATE) or "what date is 30 days from this date?" (INTEGER-OF-DATE, add 30, DATE-OF-INTEGER). Instead of you counting days and months, the function does it. You give it a date (or nothing for "now") and get back a value you can store or use in calculations.

Common Date-Time Functions

CURRENT-DATE

FUNCTION CURRENT-DATE takes no arguments and returns the current date and time. The return format is implementation-defined; often it is a 21-character string where positions 1–4 are year, 5–6 month, 7–8 day, 9–10 hour, 11–12 minute, 13–14 second, and the rest may be hundredths and timezone. Extract the date with reference modification: MOVE FUNCTION CURRENT-DATE(1:8) TO WS-YYYYMMDD gives you an 8-character date. Extract time with (9:6) for HHMMSS.

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       01  WS-DATE-TIME    PIC X(21).
       01  WS-YYYYMMDD    PIC X(8).
       01  WS-HHMMSS      PIC X(6).
       
       MOVE FUNCTION CURRENT-DATE TO WS-DATE-TIME
       *> Extract date (positions 1-8) and time (9-14 or 9-6 depending on format)
       MOVE WS-DATE-TIME(1:8) TO WS-YYYYMMDD
       MOVE WS-DATE-TIME(9:6) TO WS-HHMMSS

INTEGER-OF-DATE and DATE-OF-INTEGER

INTEGER-OF-DATE converts a date (typically in YYYYMMDD or similar format) to an integer that represents that date (e.g. days since a base date). DATE-OF-INTEGER converts that integer back to a date. The base date and exact argument/return formats are defined by your COBOL implementation. Use these for date arithmetic: convert to integer, add or subtract days, convert back. This correctly handles month and year boundaries and leap years.

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       *> Add 30 days to WS-START-DATE (PIC 9(8) YYYYMMDD)
       01  WS-START-DATE   PIC 9(8) VALUE 20240101.
       01  WS-INT-DATE     PIC S9(9).
       01  WS-END-DATE     PIC 9(8).
       
       COMPUTE WS-INT-DATE = FUNCTION INTEGER-OF-DATE(WS-START-DATE) + 30
       MOVE FUNCTION DATE-OF-INTEGER(WS-INT-DATE) TO WS-END-DATE
       *> WS-END-DATE now holds the date 30 days later

Step-by-Step: Get Today and Format It

• Move FUNCTION CURRENT-DATE to an alphanumeric field long enough for the return value (e.g. 21 characters).
• Use reference modification to copy the date portion (e.g. 1:8) into a YYYYMMDD field and the time portion (e.g. 9:6) into an HHMMSS field if needed.
• For display, build a formatted string (e.g. MM/DD/YYYY) using the extracted parts and STRING or separate MOVE statements.

Best Practices

• Check your compiler documentation for the exact CURRENT-DATE format and for INTEGER-OF-DATE/DATE-OF-INTEGER argument and return types.
• Use INTEGER-OF-DATE and DATE-OF-INTEGER for date arithmetic instead of manual day/month/year logic.
• Use reference modification or subordinate items to extract date and time parts from CURRENT-DATE so the code is clear and maintainable.

Related Concepts