PRODUCT  :  C++                                    NUMBER  :  645
  VERSION  :  All
       OS  :  DOS
     DATE  :  September 18, 1991                       PAGE  :  1/2

    TITLE  :  Floating Point Formats Not Linked




  What is the floating point emulator and when is it used?

  The floating  point emulator is used to manipulate floating point
  numbers in runtime library functions like scanf() and atof().

  What causes the error?

  When  parsing  your  source file, if the  compiler  encounters  a
  reference to the address of a float, it sets a  flag  to have the
  linker link in the floating point emulator.  There are some cases
  in which the  reference  to  the  float  is a bit obscure and the
  compiler does not  detect  the  need  for the emulator.  The most
  common is using scanf()  with  a pointer to a struct containing a
  float.

  For example:

       struct foo
       {
            float fvar;
       };

       void main(void)
       {
            struct foo s1, *s2 = &s1;
            scanf("%f", &s1->fvar);
       }

  These situations  usually  occur  during  the  initial  stages of
  program  development.    Normally,  once  the  program  is  fully
  developed, the emulator will  be  used in such a fashion that the
  compiler can accurately determine when to link in the emulator.

  How can I force the formats to be linked?

  To force linking of the floating point emulator to be linked into
  an application,  just  include  the  following  function  in your
  program:


















  PRODUCT  :  C++                                    NUMBER  :  645
  VERSION  :  All
       OS  :  DOS
     DATE  :  September 18, 1991                       PAGE  :  2/2

    TITLE  :  Floating Point Formats Not Linked




       void LinkFloat (void)
       {
           float a=0, *b=&a;  /* cause emulator to be linked */
           a=*b;              /* suppress warning var not used */
       }

  You do not need  to  call this function, just include it anywhere
  in your program.  Once your project has reached  its  full  size,
  you will most likely be able to remove it from the program.

  When will this be changed?

  There are no current plans to change the inner  workings  of  the
  compiler  because the intent is to  avoid  linking  the  floating
  point emulator (about 1k of overhead) when it is not required.

  Special Cases

  An exception to this  rule  occurs with Turbo C version 2.01 when
  using the atof() function.  This is a mistake and  is  fixed in a
  patch file called tc21pt.arc, which is available on CompuServe in
  forum  BPROGB,  LIB  5.  It is also available for download on the
  Borland BBS which can be reached at 408.439.9096.