Author Topic: LOCATE can be a pain in the ASCII.  (Read 3496 times)

0 Members and 1 Guest are viewing this topic.

Offline Pete

  • Forum Resident
  • Posts: 2361
  • Cuz I sez so, varmint!
    • View Profile
LOCATE can be a pain in the ASCII.
« on: September 26, 2020, 04:06:30 pm »
A newcomer asked some questions about the LOCATE statement, recently. It made me recall some past issues I had , decades ago.Just for discussion sake, I thought I'd post this. View the comments in the code to see what's happening.

Code: QB64: [Select]
  1. PRINT "This will not fill the screen, as intended..."
  2. x$ = STRING$(_WIDTH * _HEIGHT, 219)
  3. PRINT x$;
  4. PRINT "But this will..." ' And why does this PRINT statement appear on row #2, after a CLS statement?
  5. x$ = STRING$(_WIDTH * (_HEIGHT - 1), 219) ' Print all but last row.
  6. PRINT x$;
  7. PRINT STRING$(_WIDTH, 219); ' Print last row, separately.

I recall doing my first WP program that I made some special conditions when the cursor went past the width of the screen, and was hanging in limbo until the next statement determined its fate. I wish I saved the initial problem somewhere, but I didn't, so sorry for being rather vague here. I'm just pointing out that LOCATE can seem to act a bit fickle at time, in my opinion, but I'm sure if all the workings were taken into consideration, there would be reasons for it having to act in a certain way, so as to not mess up other uses, I suppose. Anyway, run the example and see what you think. For whatever reason, printing to the entire screen with a semi-colon scrolls it, but if you leave the last line blank, relocate the cursor to that last line, and then print a solid row with a semi-colon, you're good.

The other part that is unusual is the "But this will..." statement should print on row #1, not row #2. It follows a CLS statement, which should reset LOCATE to 1, 1, but that STRING$ print statement appears to be interfering with that expected result.

/ramble

Pete
Want to learn how to write code on cave walls? https://www.tapatalk.com/groups/qbasic/qbasic-f1/