newlib/libc/stdlib/efgcvt.c

   1 /*
   2 FUNCTION
   3 <<ecvt>>, <<ecvtf>>, <<fcvt>>, <<fcvtf>>---double or float to string
   4
   5 INDEX
   6         ecvt
   7 INDEX
   8         ecvtf
   9 INDEX
  10         fcvt
  11 INDEX
  12         fcvtf
  13
  14 SYNOPSIS
  15         #include <stdlib.h>
  16
  17         char *ecvt(double <[val]>, int <[chars]>, int *<[decpt]>, int *<[sgn]>);
  18         char *ecvtf(float <[val]>, int <[chars]>, int *<[decpt]>, int *<[sgn]>);
  19
  20         char *fcvt(double <[val]>, int <[decimals]>,
  21                    int *<[decpt]>, int *<[sgn]>);
  22         char *fcvtf(float <[val]>, int <[decimals]>,
  23                     int *<[decpt]>, int *<[sgn]>);
  24
  25 DESCRIPTION
  26 <<ecvt>> and <<fcvt>> produce (null-terminated) strings of digits
  27 representating the <<double>> number <[val]>.
  28 <<ecvtf>> and <<fcvtf>> produce the corresponding character
  29 representations of <<float>> numbers.
  30
  31 (The <<stdlib>> functions <<ecvtbuf>> and <<fcvtbuf>> are reentrant
  32 versions of <<ecvt>> and <<fcvt>>.)
  33
  34 The only difference between <<ecvt>> and <<fcvt>> is the
  35 interpretation of the second argument (<[chars]> or <[decimals]>).
  36 For <<ecvt>>, the second argument <[chars]> specifies the total number
  37 of characters to write (which is also the number of significant digits
  38 in the formatted string, since these two functions write only digits).
  39 For <<fcvt>>, the second argument <[decimals]> specifies the number of
  40 characters to write after the decimal point; all digits for the integer
  41 part of <[val]> are always included.
  42
  43 Since <<ecvt>> and <<fcvt>> write only digits in the output string,
  44 they record the location of the decimal point in <<*<[decpt]>>>, and
  45 the sign of the number in <<*<[sgn]>>>.  After formatting a number,
  46 <<*<[decpt]>>> contains the number of digits to the left of the
  47 decimal point.  <<*<[sgn]>>> contains <<0>> if the number is positive,
  48 and <<1>> if it is negative.
  49
  50 RETURNS
  51 All four functions return a pointer to the new string containing a
  52 character representation of <[val]>.
  53
  54 PORTABILITY
  55 None of these functions are ANSI C.
  56
  57 Supporting OS subroutines required: <<close>>, <<fstat>>, <<isatty>>,
  58 <<lseek>>, <<read>>, <<sbrk>>, <<write>>.
  59
  60 NEWPAGE
  61 FUNCTION
  62 <<gcvt>>, <<gcvtf>>---format double or float as string
  63
  64 INDEX
  65         gcvt
  66 INDEX
  67         gcvtf
  68
  69 SYNOPSIS
  70         #include <stdlib.h>
  71
  72         char *gcvt(double <[val]>, int <[precision]>, char *<[buf]>);
  73         char *gcvtf(float <[val]>, int <[precision]>, char *<[buf]>);
  74
  75 DESCRIPTION
  76 <<gcvt>> writes a fully formatted number as a null-terminated
  77 string in the buffer <<*<[buf]>>>.  <<gcvtf>> produces corresponding
  78 character representations of <<float>> numbers.
  79
  80 <<gcvt>> uses the same rules as the <<printf>> format
  81 `<<%.<[precision]>g>>'---only negative values are signed (with
  82 `<<->>'), and either exponential or ordinary decimal-fraction format
  83 is chosen depending on the number of significant digits (specified by
  84 <[precision]>).
  85
  86 RETURNS
  87 The result is a pointer to the formatted representation of <[val]>
  88 (the same as the argument <[buf]>).
  89
  90 PORTABILITY
  91 Neither function is ANSI C.
  92
  93 Supporting OS subroutines required: <<close>>, <<fstat>>, <<isatty>>,
  94 <<lseek>>, <<read>>, <<sbrk>>, <<write>>.
  95 */
  96
  97 #define _XOPEN_SOURCE
  98 #define _XOPEN_SOURCE_EXTENDED
  99 #include <_ansi.h>
 100 #include <reent.h>
 101 #include <stdio.h>
 102 #include <stdlib.h>
 103 #include "local.h"
 104
 105 char *  ecvtbuf (double, int, int*, int*, char *);
 106 char *  fcvtbuf (double, int, int*, int*, char *);
 107
 108 char *
 109 fcvt (double d,
 110         int ndigit,
 111         int *decpt,
 112         int *sign)
 113 {
 114   return fcvtbuf (d, ndigit, decpt, sign, NULL);
 115 }
 116
 117 char *
 118 fcvtf (float d,
 119         int ndigit,
 120         int *decpt,
 121         int *sign)
 122 {
 123   return fcvt ((float) d, ndigit, decpt, sign);
 124 }
 125
 126
 127 char *
 128 gcvt (double d,
 129         int ndigit,
 130         char *buf)
 131 {
 132   char *tbuf = buf;
 133   if (d < 0) {
 134     *buf = '-';
 135     buf++;
 136     ndigit--;
 137   }
 138   return (_gcvt (_REENT, d, ndigit, buf, 'g', 0) ? tbuf : 0);
 139 }
 140
 141
 142 char *
 143 gcvtf (float d,
 144         int ndigit,
 145         char *buf)
 146 {
 147   double asd = d;
 148   return gcvt (asd, ndigit, buf);
 149 }
 150
 151
 152 char *
 153 ecvt (double d,
 154         int ndigit,
 155         int *decpt,
 156         int *sign)
 157 {
 158   return ecvtbuf (d, ndigit, decpt, sign, NULL);
 159 }
 160
 161 char *
 162 ecvtf (float d,
 163         int ndigit,
 164         int *decpt,
 165         int *sign)
 166 {
 167   return ecvt ((double) d, ndigit, decpt, sign);
 168 }