5 ms·

I had a similarly fun time back in the 90s debugging a VBA script a co-worker had written for an Excel spreadsheet. She was looping through a bunch of time val

I had a similarly fun time back in the 90s debugging a VBA script a co-worker had written for an Excel spreadsheet. She was looping through a bunch of time values... ... so she named her variable "time" ... which, when modified, would (naturally) set the system time of the computer. I'm not sure whether they've fixed that one yet.

ja27 14y ago
At least once a quarter I'd have a student working on some programming assignment on one of our unix-ish systems where they named the executable "test" and couldn't figure out why it wasn't doing anything they expected. I also got to the point with FORTRAN (yes, I'm old) students where I'd cut them off and tell them to count the columns and make sure each line started with 6 blanks, not 5. My favorite bug is still some piece of C code buried in a library that was like this: if (flag == TRUE) ... Or there's the old for loop typo (much easier to detect on today's high-DPI screens): for(float x=0.0; x < 3,4; x = x + 0.1) ...
- viraptor 14y ago
  I don't get what's wrong with the flag check apart from being a bit too verbose.
  - mpyne 14y ago
    TRUE is going to be 1. The flag value might have the value 0x2, 0x4, 0xsomething_else, etc., which will not equal exactly 1 (TRUE). What you want varies but is probably something like: if (flag & FLAG_VALUE) ... if (flag) .... if ((flag & FLAG_VALUE) == TRUE) ... that kind of thing.
    - geon 14y ago
      if ((flag & FLAG_VALUE) == TRUE) ... That would still check if flag is 1, right?
      - azth 14y ago
        That is correct.
        mpyne 14y ago
        Indeed, great catch (this is why I use things like QFlags now, as it has a simple "testFlag" method)
    - to3m 14y ago
      flag&FLAG_VALUE will be FLAG_VALUE or 0, so unless FLAG_VALUE==TRUE the answer could be wrong. Suggest (flag&FLAG_VALUE), or, if you need the expression to be of type bool, ((flag&FLAG_VALUE)!=0) or (!!(flag&FLAG_VALUE)).
      - mpyne 14y ago
        Very true, I just checked to see if I can edit but I can't, so mea culpa.
    - ja27 14y ago
      Boolean true / TRUE wasn't defined in any standard way before C99. Back in the "olden days", most programmers #defined it as 1, but not always. I ran into one of those "not always" cases in some inherited code.
- anonymouz 14y ago
  I'm curious about the test one. Do you have "." in your PATH? Or do students simply not realize that they should call their program as ./test anyway?
  - ja27 14y ago
    Student accounts had "." in their PATH by default. I'm sure someone did it to keep students from asking why their program wouldn't run at all. Fun times.
bch 14y ago
I had this with Perl, using $a or $b for a throw-away script, but Perl uses these internally for sorting. Didn't take -too- long to sort it out, but certainly broke my flow.
- jey 14y ago
  using $a or $b for a throw-away script, but Perl uses these internally for sorting Everything I learn about Perl just makes me hate it more. But a lot of people seem to love it -- it must have some redeeming qualities, right?
  - kamaal 14y ago
    Everything I learn about the world makes me hate it more. But a lot of people seem to love it --it must have some redeeming qualities, right? Answer: Yes, depends on where in the world you live.
  - draegtun 14y ago
    There is nothing to be afraid of here, sort just makes use of localised $a & $b package variable names as references to the sort block: our $a = 100; # using $a package variable # then later do a sort on @list my @sorted = sort { $a cmp $b } @list; # @sorted worked correctly, $a = 100 had no effect on it # and $a is still 100 And if we change our to my (so lexical variable) then script will fail to compile giving the fatal error: Can't use "my $a" in sort comparison at... For more information on sort see: http://perldoc.perl.org/functions/sort.html http://perldoc.perl.org/functions/sort.html PS. The OP problem may have been due to issue/bug in older version of Perl. Also using use strict; use warnings do help highlight issues with code.
    - bch 14y ago
      Indeed. First 3 lines of all perl code for me are: #!/usr/bin/env perl use strict; use warnings;
Achshar 14y ago
Are you saying changing the value of a variable in excel changes system time? Isn't that a little... nevermind. What about the privileges required to change time? Did it bypass them or it only worked for admins?
- StavrosK 14y ago
  What privileges? It was Windows in the 90s.
  - Achshar 14y ago
    Oops, missed that part.
    - StavrosK 14y ago
      Yes, it was the excellent security model of "let's not bother with security models".
niggler 14y ago
Time is a reserved keyword according to MS-VBAL. My guess is that excel itself didn't follow their standard ...

ja27 14y ago

At least once a quarter I'd have a student working on some programming assignment on one of our unix-ish systems where they named the executable "test" and couldn't figure out why it wasn't doing anything they expected. I also got to the point with FORTRAN (yes, I'm old) students where I'd cut them off and tell them to count the columns and make sure each line started with 6 blanks, not 5. My favorite bug is still some piece of C code buried in a library that was like this: if (flag == TRUE) ... Or there's the old for loop typo (much easier to detect on today's high-DPI screens): for(float x=0.0; x < 3,4; x = x + 0.1) ...

viraptor 14y ago
I don't get what's wrong with the flag check apart from being a bit too verbose.
- mpyne 14y ago
  TRUE is going to be 1. The flag value might have the value 0x2, 0x4, 0xsomething_else, etc., which will not equal exactly 1 (TRUE). What you want varies but is probably something like: if (flag & FLAG_VALUE) ... if (flag) .... if ((flag & FLAG_VALUE) == TRUE) ... that kind of thing.
  - geon 14y ago
    if ((flag & FLAG_VALUE) == TRUE) ... That would still check if flag is 1, right?
    - azth 14y ago
      That is correct.
      - mpyne 14y ago
        Indeed, great catch (this is why I use things like QFlags now, as it has a simple "testFlag" method)
  - to3m 14y ago
    flag&FLAG_VALUE will be FLAG_VALUE or 0, so unless FLAG_VALUE==TRUE the answer could be wrong. Suggest (flag&FLAG_VALUE), or, if you need the expression to be of type bool, ((flag&FLAG_VALUE)!=0) or (!!(flag&FLAG_VALUE)).
    - mpyne 14y ago
      Very true, I just checked to see if I can edit but I can't, so mea culpa.
  - ja27 14y ago
    Boolean true / TRUE wasn't defined in any standard way before C99. Back in the "olden days", most programmers #defined it as 1, but not always. I ran into one of those "not always" cases in some inherited code.
anonymouz 14y ago
I'm curious about the test one. Do you have "." in your PATH? Or do students simply not realize that they should call their program as ./test anyway?
- ja27 14y ago
  Student accounts had "." in their PATH by default. I'm sure someone did it to keep students from asking why their program wouldn't run at all. Fun times.

bch 14y ago

I had this with Perl, using $a or $b for a throw-away script, but Perl uses these internally for sorting. Didn't take -too- long to sort it out, but certainly broke my flow.

jey 14y ago
using $a or $b for a throw-away script, but Perl uses these internally for sorting Everything I learn about Perl just makes me hate it more. But a lot of people seem to love it -- it must have some redeeming qualities, right?
- kamaal 14y ago
  Everything I learn about the world makes me hate it more. But a lot of people seem to love it --it must have some redeeming qualities, right? Answer: Yes, depends on where in the world you live.
- draegtun 14y ago
  There is nothing to be afraid of here, sort just makes use of localised $a & $b package variable names as references to the sort block: our $a = 100; # using $a package variable # then later do a sort on @list my @sorted = sort { $a cmp $b } @list; # @sorted worked correctly, $a = 100 had no effect on it # and $a is still 100 And if we change our to my (so lexical variable) then script will fail to compile giving the fatal error: Can't use "my $a" in sort comparison at... For more information on sort see: http://perldoc.perl.org/functions/sort.html http://perldoc.perl.org/functions/sort.html PS. The OP problem may have been due to issue/bug in older version of Perl. Also using use strict; use warnings do help highlight issues with code.
  - bch 14y ago
    Indeed. First 3 lines of all perl code for me are: #!/usr/bin/env perl use strict; use warnings;

Achshar 14y ago

Are you saying changing the value of a variable in excel changes system time? Isn't that a little... nevermind. What about the privileges required to change time? Did it bypass them or it only worked for admins?

StavrosK 14y ago
What privileges? It was Windows in the 90s.
- Achshar 14y ago
  Oops, missed that part.
  - StavrosK 14y ago
    Yes, it was the excellent security model of "let's not bother with security models".

niggler 14y ago

Time is a reserved keyword according to MS-VBAL. My guess is that excel itself didn't follow their standard ...