ecvt, fcvt, gcvt

Purpose

     Converts a floating-point number to a string.

Library

     Standard C Library (libc.a)

Syntax

     char *ecvt (value, ndigit, decpt, sign)   char *gcvt (value, ndigit, buf)
     double value;                             double value;
     int ndigit, *decpt, *sign;                int ndigit;
                                               char *buf;
     char *fcvt (value, ndigit, decpt, sign)
     double value;
     int ndigit, *decpt, *sign;
     Description

     The ecvt,  fcvt, and  gcvt subroutines  convert floating-
     point numbers to strings.

     The  ecvt subroutine  converts the  value parameter  to a
     null-terminated string and returns  a pointer to it.  The
     ndigit parameter  specifies the  number of digits  in the
     string.  The  low-order digit is rounded.   ecvt sets the
     int pointed to by the  decpt parameter to the position of
     the  decimal  point  relative  to the  beginning  of  the
     string.  (A negative number means the decimal point is to
     the left of the digits given in the string).  The decimal
     point itself  is not  included in  the string.   The ecvt
     subroutine  also sets  the  int pointed  to  by the  sign
     parameter to a  non-zero value if the  value parameter is
     negative, and sets it to 0 otherwise.

     The fcvt subroutine functions identically to ecvt, except
     that it  rounds the  correct digit for  outputting ndigit
     digits in FORTRAN F-format.

     The  gcvt subroutine  converts the  value parameter  to a
     null-terminated string, stores it in the array pointed to
     by  the  buf  parameter,  and  then  returns  buf.   gcvt
     attempts to produce a string of ndigit significant digits
     in  FORTRAN  F-format.  If  this  is  not possible,  then
     E-format is used.  gcvt  suppresses trailing zeroes.  The
     string is  ready for printing, complete  with minus sign,
     decimal point, or exponent, as appropriate.

     The ecvt,  fcvt, and gcvt subroutines  represent the fol-
     lowing  special values  that are  specified in  ANSI/IEEE
     standard 754-1985 for binary floating-point arithmetic:

     Quiet NaN        "QNaN"

     Signalling NaN   "SNaN"
     A&infinity.      "INF"

     The sign associated  with each of these  values is stored
     into the sign parameter.  Note, also, that 0 can be posi-
     tive or negative.

     Warning:  All  three subroutines  store the strings  in a
     static area of memory whose contents are overwritten each
     time one of the subroutines is called.

     Related Information

     In  this book:   "a64l,  l64a,"   "frexp, ldexp,  modf,"
     "printf,    fprintf,   sprintf,    NLprintf,   NLfprintf,
     NLsprintf,"   and   "scanf,  fscanf,   sscanf,   NLscanf,
     NLfscanf, NLsscanf."