166 lines
3.8 KiB
C
166 lines
3.8 KiB
C
/*
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FUNCTION
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<<ecvt>>, <<ecvtf>>, <<fcvt>>, <<fcvtf>>---double or float to string
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INDEX
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ecvt
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INDEX
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ecvtf
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INDEX
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fcvt
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INDEX
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fcvtf
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SYNOPSIS
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#include <stdlib.h>
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char *ecvt(double <[val]>, int <[chars]>, int *<[decpt]>, int *<[sgn]>);
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char *ecvtf(float <[val]>, int <[chars]>, int *<[decpt]>, int *<[sgn]>);
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char *fcvt(double <[val]>, int <[decimals]>,
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int *<[decpt]>, int *<[sgn]>);
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char *fcvtf(float <[val]>, int <[decimals]>,
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int *<[decpt]>, int *<[sgn]>);
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DESCRIPTION
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<<ecvt>> and <<fcvt>> produce (null-terminated) strings of digits
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representating the <<double>> number <[val]>.
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<<ecvtf>> and <<fcvtf>> produce the corresponding character
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representations of <<float>> numbers.
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(The <<stdlib>> functions <<ecvtbuf>> and <<fcvtbuf>> are reentrant
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versions of <<ecvt>> and <<fcvt>>.)
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The only difference between <<ecvt>> and <<fcvt>> is the
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interpretation of the second argument (<[chars]> or <[decimals]>).
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For <<ecvt>>, the second argument <[chars]> specifies the total number
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of characters to write (which is also the number of significant digits
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in the formatted string, since these two functions write only digits).
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For <<fcvt>>, the second argument <[decimals]> specifies the number of
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characters to write after the decimal point; all digits for the integer
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part of <[val]> are always included.
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Since <<ecvt>> and <<fcvt>> write only digits in the output string,
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they record the location of the decimal point in <<*<[decpt]>>>, and
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the sign of the number in <<*<[sgn]>>>. After formatting a number,
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<<*<[decpt]>>> contains the number of digits to the left of the
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decimal point. <<*<[sgn]>>> contains <<0>> if the number is positive,
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and <<1>> if it is negative.
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RETURNS
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All four functions return a pointer to the new string containing a
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character representation of <[val]>.
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PORTABILITY
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None of these functions are ANSI C.
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Supporting OS subroutines required: <<close>>, <<fstat>>, <<isatty>>,
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<<lseek>>, <<read>>, <<sbrk>>, <<write>>.
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NEWPAGE
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FUNCTION
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<<gcvt>>, <<gcvtf>>---format double or float as string
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INDEX
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gcvt
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INDEX
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gcvtf
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SYNOPSIS
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#include <stdlib.h>
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char *gcvt(double <[val]>, int <[precision]>, char *<[buf]>);
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char *gcvtf(float <[val]>, int <[precision]>, char *<[buf]>);
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DESCRIPTION
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<<gcvt>> writes a fully formatted number as a null-terminated
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string in the buffer <<*<[buf]>>>. <<gcvtf>> produces corresponding
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character representations of <<float>> numbers.
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<<gcvt>> uses the same rules as the <<printf>> format
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`<<%.<[precision]>g>>'---only negative values are signed (with
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`<<->>'), and either exponential or ordinary decimal-fraction format
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is chosen depending on the number of significant digits (specified by
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<[precision]>).
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RETURNS
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The result is a pointer to the formatted representation of <[val]>
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(the same as the argument <[buf]>).
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PORTABILITY
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Neither function is ANSI C.
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Supporting OS subroutines required: <<close>>, <<fstat>>, <<isatty>>,
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<<lseek>>, <<read>>, <<sbrk>>, <<write>>.
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*/
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#define _XOPEN_SOURCE
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#define _XOPEN_SOURCE_EXTENDED
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#include <_ansi.h>
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#include <reent.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include "local.h"
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char *
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fcvt (double d,
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int ndigit,
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int *decpt,
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int *sign)
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{
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return fcvtbuf (d, ndigit, decpt, sign, NULL);
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}
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char *
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fcvtf (float d,
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int ndigit,
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int *decpt,
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int *sign)
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{
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return fcvt ((float) d, ndigit, decpt, sign);
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}
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char *
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gcvtf (float d,
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int ndigit,
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char *buf)
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{
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double asd = d;
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return gcvt (asd, ndigit, buf);
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}
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char *
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ecvt (double d,
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int ndigit,
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int *decpt,
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int *sign)
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{
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return ecvtbuf (d, ndigit, decpt, sign, NULL);
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}
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char *
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ecvtf (float d,
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int ndigit,
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int *decpt,
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int *sign)
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{
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return ecvt ((double) d, ndigit, decpt, sign);
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}
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char *
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gcvt (double d,
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int ndigit,
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char *buf)
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{
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char *tbuf = buf;
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if (d < 0) {
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*buf = '-';
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buf++;
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ndigit--;
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}
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return (_gcvt (_REENT, d, ndigit, buf, 'g', 0) ? tbuf : 0);
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}
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