Liren Large Software Subsidy 7/07.iso/c/c100/1.ddi/STDANS.ZIP/STDANS.TXT

Text File | 1988-08-20 | 18.2 KB | 401 lines

    Standard Answers to Frequently Asked Questions
      New, Improved Turbo C++

    Don Corbitt (Not for BI) 74017,3244

    Last changed 25 July 1990

This file has the goal of answering many of the common questions
seen on BPROGB regarding Borland Turbo C++.  I don't represent
Borland, any opinions are my own.

There is a similar file called STDANS.TXT in DL5 of BPROGB.  It
answers common questions that apply to TC++ and TC (and programming
in general).  The file your are now reading is specific to Turbo C++
version 1.0.

Overview
==============
Enable warnings.
Many programming errors can be diagnosed by the compiler.  If
you enable all warning messages you have a much better chance of
writing programs that work the first time.

Formatted messages
When you leave messages regarding problems, please use the
/POST UNFORMATTED option.  Otherwise, CIS (Compuserve Information
Service) will re-format your program into a jumbled mess.

RTM - Read The Manual - readme and helpme!.doc
Before spending $$$ on CIS, it is often useful to read the
documentation.  Also, look at the files README and HELPME!.DOC
included with TC.  They list fixes to many common programming
errors.  The TC++ 1.0 manuals have a lot of good information.

HELP ME!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
========================================
If you're just getting started, and nothing seems to be working,
see these questions first:
  Q4  - assembly code and 3rd party libraries (also Q24)
  Q9  - editor hangs when copying blocks of text
  Q15 - large model and stack checking
  Q19 - overlays and data-only modules
  Q22 - overlays and exit() with C++ or atexit() functions
  Q23 - mouse driver incompatible
  Q24 - assembly code and 3rd party libraries
  Q31 - TDxxx/TProfxxx don't load

TAPCIS
Q1. What is TAPCIS, and how does it help?
A. TAPCIS is a program that calls CIS, checks for new messages,
saves them on disk, and hangs up.  Then it lets you examine the
messages at your own pace, write replies, etc.  TAPCIS then calls
CIS back, and uploads replies you have written.  It saves a lot
on connect charges.  GO TAP for more information.  It is
shareware, and registration is expected if you like it.  Another
program (ATO) is free, but I haven't used it.

OS|2/Windows linking
Q2. Can I use TC for OS|2 or Windows?
A. Windows and OS/2 are both 'strategic areas' for Borland. This
means that eventually BI's main products will work under DOS,
Windows, and OS|2-PM.  At this time, the outside world doesn't
know what the timetable is.  It doesn't do any good to ask for
specific dates, because the people that know aren't allowed to
say.  "Borland does not pre-announce product releases."

Q3. Why is this C++ program illegal?
  void main() {
    int i;
    for (i=0; i<10; i++)
      for (int j=0; j<10; j++)
    ;
    printf("j = %d\n", j);
  }
A. The AT&T C++ 2.0 specification stated that variables can't be
  declared in such a way that the initializer may never execute, but
  they are still in scope.  Turbo C implements this 2.0 rule.  This
  rule was changed back in the AT&T 2.1 spec, and I expect a future
  version from Borland will follow C++ 2.1.
  A simple workaround is to add braces around the inner 'for' loop:

  void main() {
    for (int i=0; i<10; i++) {
      for (int j=0; j<10; j++)
        ;
    }
  }

Q4. Why does malloc() corrupt memory?
   Why does my program fail in mysterious ways?
   Why does my program die when linked with TLINK 3.0, but
   work with TLINK 2.0?
   (etc.)
A. If you are linking in any assembly code, look for the DOSSEG
   directive.  DOSSEG was defined for a previous version of MSC
   compilers, and is not currently needed.  In fact, it conflicts
   with the segment ordering of Turbo C++.  Previous versions of
   TLINK ignored the DOSSEG record, so they (often) worked.  The
   solution is to remove DOSSEG from your assembly source, and
   reassemble.  If you are linking with third party libraries
   and don't have the source, ask them to send you a new library.
   If they can't/won't, try linking in the integrated environment,
   and find a new library vendor that is easier to work with! :-)

Q5. Why does qsort() give a warning/error, when it worked fine under
   TC 2.0.
A. TC++ 1.0 is more strict in ANSI compliance.  It is warning you
   that your program may not work on certain computers.  Two examples
   of correct compare functions are:

  /* if sorting an array of integers */
  int fcmp(void const *p1, void const *p2) {
    const int *ip1 = p1;
    const int *ip2 = p2;
    if (*ip1 < *ip2) return -1;
    if (*ip1 > *ip2) return 1;
    return 0;
  }

  /* if sorting an array of strings */
  int fcmp(void const *p1, void const *p2) {
    return strcmp(p1, p2);
  }

Q6. When I use overlays, I get a linker warning that setjmp and
   longjmp are multiply defined.  Why?
A. OVERLAY.LIB includes its own setjmp and longjmp.  This warning
   is expected, and correct.  You can disable it if you wish.

Q7. Why is Turbo Debugger 2.0 so much slower than TD 1.5?
A. For some machines, TD2 seems much slower, but not on others.
   Suggestions for increasing speed are
     1) disable execution history each time you run
     2) update your mouse driver to latest release
     3) disable use of mouse in TD
     4) use MOUSTR.LZH from PCVENB DL 6 to speed up operation of
    recent Microsoft mouse drivers

Q8. Can I place third party libraries in VROOM overlays?
A. Yes, if the vendor compiled with the -Y switch, or you have
   source and recompile with -Y.  If your vendor won't do so,
   tell Borland and they will try to encourage them to fully
   support VROOM.

Q9. When I try to copy a block in the IDE, the system hangs.
A. There is a bug in the editor - if the file ends in Ctrl-Z, the
   last line is not terminated with CRLF, and there are an odd
   number of chars in the last line, this will happen.
   Workarounds are to terminate with CRLF, or remove the Ctrl-Z.
   TC 2.0 inserts Ctrl-Z, while simply saving the file from TC++ 1.0
   will strip them.

Q10. I ordered the ProPack upgrade option for $125.  Why didn't I get
   new TASM manuals?
A. Although TC++ 1.0 is _not_ an upgrade from TC 2.0, the Pro-Pack
   part of the package (TD, TASM) is an upgrade.  TASM had very few
   changes, which are documented, so no new manuals were sent out.
   There is a new quick reference guide, which is useful.  If you
   don't have TASM 1.0 manuals, you should have ordered the $145
   special package which is for people that don't have the Propack,
   and need all the manuals.  A few people threw a tantrum when their
   package arrived sans TASM manuals.  Borland agreed to send them
   TASM 2.0 manuals, and make sure any future purchasers know what
   each order contains.  The opinion of most people who received
   new manuals is that they shouldn't have bothered.

Q11. I ordered the upgrade through Borland for $xxx, and the next week
   I found the same package for $xxx-10 at the local "Software Is Us"
   store?  Why is Borland ripping off its loyal customers!!!!!
A. There are two parts to this answer...
    1) Take a deep breath, count to ten, exhale slowly.
       Now that you feel more relaxed...
    2) C++ is a new product, so the special deals for past customers
       are not as special.  Each store/distributor is free to charge
       what it wishes for software, including selling at or below
       cost.  Since they buy in huge quantity, they get very
       good prices, and handling/postage is much lower than
       individual sales.  So I recommend checking with your local
       discount house before placing an order direct to Borland.
    PS - Egghead Software had a typo in their advertisements.
       It looked like they were selling TC++ Pro Pack for $90,
       when it was really just TC++ 1.0, no TASM/TD/TProf, etc.

Q12. What happened to the inportb() and outportb() inline macros
   in dos.h?
A. They accidentally got left out.  You can copy the definitions
   below into dos.h after the geninterrupt() definition.  BTW,
   there are also definitions for word IO, but they don't work
   correctly in this release of the compiler.

  unsigned char    _Cdecl  __inportb__    (int portid);
  #define inportb(portid) __inportb__(portid)/* Byte IN instruction */

  void    _Cdecl  __outportb__    (int portid, unsigned char value);
  #define outportb(portid, v) __outportb__(portid,v)/* Byte OUT instruction */

Q13. Why do vXprintf() routines expect that the __arglist parameter
   point to the stack?
A. Because programs that follow the rules of STDARG.H always pass
   pointers to their stack arguments.  Many months ago someone from
   Borland asked if that would be a reasonable requirement, and no
   one could think of a reason why not.
   Calling a function expecting a va_list with some other object is
   non-portable, and doesn't work in this release of the compiler.
   Fix your program.

Q14. Why does linking with WILDARGS.OBJ cause my program to crash?
A. There appears to be a bug using WILDARGS.OBJ and large model
   programs.  Found by Hyman Rosen 74716,3415.  He announced a
   fixed WILDARGS.OBJ has been uploaded to DL4, it may have been
   moved to DL3 by now.  There have also been reports of another bug
   in tiny model, which should soon be fixed.

Q15. Why does my large model program not work?
A. If stack checking is enabled, turn it off.  Stack check in
   large model is said to not work properly.

Q16. What is a good book for learning C++ programming?
A. C++ Primer, Stanley B. Lippman, ISBN 0-201-16487-6.  For a
   reference book, see Annotated C++ Reference Manual, Ellis &
   Stroustrup, ISBM 0-201-51459-1.

Q17. Why does the linker complain about missing functions when
   I use C++ streams?
A. If you have selected Unsigned Chars:ON, change back to off,
   or edit the <iostream.h> file on lines 577, 593, 597 to be
   (const signed char *) in place of (const char *).

Q18. Where are the programs TCCNVT.EXE and PRJ2MAKE.EXE?
A. These utilities were not completed in time for shipment, and
   should have been removed from the manuals.  There is no
   information on future plans regarding them.

Q19. Why does my program crash when I link with overlays, but work
   ok without them?
A. Are you overlaying any modules that are data-only?  Create a
   detailed .MAP file, and see if any of the code segments being
   overlayed are 0 bytes long.  If so, don't overlay that module.

Q20. Why doesn't the preprocessor 'stringize' my macro?  This works
   OK in TC 2.0:
   #define TEMP 5
   #define STR(x) #x
     printf("TEMP is %s\n", STR(TEMP));
A. ANSI has defined how the preprocessor converts macros.  This will
   work:
   #define STR(x) STR1(x)
   #define STR1(x) #x

Q21. Why doesn't MK_FP work the same way?
A. For most arguments to the MK_FP macro you will get the same results.
   However, if you are passing a long value, you may get something
   unexpected.  You should pass two integers as parameters.

Q22. I'm using overlays and C++.  Why does my system crash when exit() is
   called?
A. There is a bug in c0.asm.  Either don't call exit() when using overlays
   and C++, or make this change to c0.asm, and run BUILDC0.BAT.
   To change your c0.asm, follow these steps:
     1) unzip the file STARTUP.ZIP in /turboc/examples
     2) edit C0.ASM, moving these lines
                mov     byte ptr cs:JA_JB,72h
                mov     byte ptr cs:StartExit+1,0
        to before the
                call    _main
     3) run the BUILD-C0 batch file
     4) link with the new C0x.OBJ file

Q23. Nothing seems to be working.  I get crashes when compiling, or
   running program that seemed to work before.  What's wrong?
A. A common cause of mysterious crashes is using an old mouse driver.
   TC (and TD, TProf, etc) use some mouse driver features that old
   mice don't have.  This allows them to share the mouse between the
   program being tested, and TC.  An old driver can cause various
   problems.  Note that your mouse may work with other programs,
   and still not support the functions TC/TD require.
     You can get new drivers at these locations:
     Mouse Systems Version 6.1  [phone]
     Logitech      Version 4.1  ????
     Microsoft     Version      ????
     Genius        Version      ????

Q24. Why am I getting memory overwrites at run time?
A. If you link any code that defines CONST segments this will
   confuse TLINK.  Either you need to add CONST segments to
   the proper place in C0.ASM, or remove the CONST segments
   from your code.

Q25. How can I tell if I'm linking in improper assembly routines?
A. Create a detailed map file.  The segment order should in
   general be as follows:

 Start  Stop   Length Name               Class  Comments
 00000H 00433H 00434H _TEXT              CODE   One or more CODE segments
 01AC5H 01D13H 0024FH TZSET_TEXT         CODE
 01D20H 022C2H 005A3H _DATA              DATA   One or more DATA segments
 022CEH 022D9H 0000CH _SCNSEG            DATA
 022DAH 02367H 0008EH _BSS               BSS    The _BSS segment
 02368H 02368H 00000H _BSSEND            STACK  Then _BSSEND with class STACK
 02370H 023EFH 00080H _STACK             STACK  Then finally STACK

Q26. TLink crashes when linking in my own ASM file?
A. If you enabled debugging symbols (/zi), and have multiple symbols
   with the same name (@@1:, etc) this may confuse TLINK.  Change
   the symbol names, or use the (/zd) option.

Q27. Why are my CIS messages being erased and no one answers them?
A. Have you considered changing deodorant?  Just joking - it's nothing
   personal.  There are (at least) four possible explanations:
     a) You are using Compuserve Navigator.  I've heard that it can be
    difficult to re-read messages you have sent.
     b) People saw your message, answered it, but you didn't check back
    quickly enough.  Compuserve limits the number of messages that
    can exist.  Each time a new message is posted, an old one gets
    deleted.  Scroll rate can be 24 hours when a new product is just
    released, or several days when things are quiet.  Check back
    in 24 hours, and again 48 hours after leaving your question.
     c) People saw your message, but didn't know the answer to the
    question.  The "For BI" volunteers answer questions they know the
        answer to, but pass on some questions to Borland support.  After
        several days of no response, repost asking if your message was
        seen, and if anyone has even a slight hint what the answer was.
     d) Your message contained a personal attack on a member of the forum.
        These messages are made private, and the culprit is admonished to
        use better mannors.
   Remember that most of the answers posted here are by volunteers, trying
   to help.  If you slip through the cracks, it is better to assume overwork
   and confusion than malice and incompetence.

Q28. Why can't I use TD386 with (QEMM, 386Max, CEMM, other 386 control
   programs)?
A. To do its thing, TD386 needs to be in charge of the 386.  These EMS
   emulators also need to have the same control.  There is a standard for
   virtual 8086 emulators, VCPI.  Unfortunately, this standard doesn't
   contain calls for supporting the needs of TD386.  Yet another control
   standard is being released DPMI (Dos Protect Mode Interface), which
   Borland is supporting.  Hopefully a future version of TD386 and QEMM
   will support DPMI.  You may be able to use TD286 if your memory
   manager is VCPI compatible.

Q29. Why doesn't __emit__(&var) work?
A. Because it is broken in TC++ 1.0.  It doesn't place the address/
   offset of the variable.  Sorry.

Q30. I'm using C++, and trying to link in some C or ASM code.  Why can't
   the linker find some symbols?
A. C++ tries to prevent programmer errors by encoding the arguments of
   a function in the function name.  You can get around this by declaring
   your extern functions as "C" as follows:
     extern "C" int foo(int __arg1, int __arg2);
   If you have a section of declarations, you can bracket them with
     extern "C" {
       int foo(int __arg1, int __arg2);
       float bar(float __arg);
     }
   See the standard header files for examples of this method.

Q31. Why don't TD386 or TProf work on my system?
A. If your environment variables take up more than 512 bytes, some of
   the TDxxx/TProfxxx programs won't work.  You can remove environment
   variables temorarily while running these programs.

Q32. Why is a variable changed after longjmp() is called?
A. It appears that setjmp()/longjmp() don't properly restore the
   DI register.  A workaround is to use _DI in the routine that
   calls setjmp(), so the compiler doesn't put anything in that
   register.

Q33. Why does my project file keep getting larger?
A. There is a problem with TC++ saving extra information in the
   project file each time the file is saved.  This can be worked
   around by setting Options/Environment/Preferences/Auto Save Project
   to OFF, and only saving your project file when you make changes.
   Another workaround may be to clear the contents of the clipboard.

Q34. When passing a structure or structure pointer, why do I need to
   declare it twice?  Shouldn't the structure definition in the function
   prototype also declare the structure?
A. No, a structure declared in a function prototype goes out of scope at
   the end of the prototype.  This is for ANSI compatibility.
   Example:
     /* struct y; /* uncomment this to make it work */
     void foo(struct y *yp);
     struct y {int a;};
     int foo(struct y *yp) { return y->a; }
   The first 'struct y' goes out of scope at the end of the prototype.
   You should uncomment the previous tag (or move the struct definition
   before the function prototype) to fix your bug.

Q35. Is the switch for snow checking broken/backwards in TCINST?
A. Yes, to disable snow checking, set it to enable, and vice versa.


If any of this information is outdated, or not correct, or if you
have any suggestions for other items to cover, please let me know.
I will try to update this file (and STDANS.TXT on DL5) several times
a year, but only if I get the feeling it is useful to others.

    Don Corbitt  74017,3244
    Sunnyvale, California