Q51735: Clock Function Sets errno

Article: Q51735
Product(s): See article
Version(s): 5.00 5.10 | 5.00 5.10
Operating System(s): MS-DOS | OS/2
Keyword(s): ENDUSER | s_quickc s_quickasm | mspl13_c
Last Modified: 16-JAN-1990

Question:

Why does the clock function set errno?

Response:

The clock function uses intdos() to read the system date and time.
When intdos() calls the date/time interrupt, the carry flag is set
upon return. The intdos() function interprets the carry flag as an
error and sets errno to the value in AL. In the case of a request for
the system date, AL (and therefore, errno) contains the day of the
week.

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