gcvt.c

<B>Digital的Unix操作系统VAX 4.2源码</B>

/*	@(#)gcvt.c	4.1	ULTRIX	7/3/90	*/
/************************************************************************
 *									*
 *			Copyright (c) 1988 by				*
 *		Digital Equipment Corporation, Maynard, MA		*
 *			All rights reserved.				*
 *									*
 *   This software is furnished under a license and may be used and	*
 *   copied  only  in accordance with the terms of such license and	*
 *   with the  inclusion  of  the  above  copyright  notice.   This	*
 *   software  or  any  other copies thereof may not be provided or	*
 *   otherwise made available to any other person.  No title to and	*
 *   ownership of the software is hereby transferred.			*
 *									*
 *   This software is  derived  from  software  received  from  the	*
 *   University    of   California,   Berkeley,   and   from   Bell	*
 *   Laboratories.  Use, duplication, or disclosure is  subject  to	*
 *   restrictions  under  license  agreements  with  University  of	*
 *   California and with AT&T.						*
 *									*
 *   The information in this software is subject to change  without	*
 *   notice  and should not be construed as a commitment by Digital	*
 *   Equipment Corporation.						*
 *									*
 *   Digital assumes no responsibility for the use  or  reliability	*
 *   of its software on equipment which is not supplied by Digital.	*
 *									*
 ************************************************************************/
/************************************************************************
 *			Modification History				*
 *									*
 * INTL	3-Mar-1987, Andy Gadsby						*
 *	Updated to allow arbitrary radix character.			*
 *									*
 ************************************************************************/
/*
 * gcvt  - Floating output conversion to
 * minimal length string
 */

char	*ecvt();

char *
gcvt(number, ndigit, buf)
double number;
char *buf;
{
	int sign, decpt;
	register char *p1, *p2;
	register i;
	extern char _lc_radix;			/* INTL radix character */

	p1 = ecvt(number, ndigit, &decpt, &sign);
	p2 = buf;
	if (sign)
		*p2++ = '-';
	for (i=ndigit-1; i>0 && p1[i]=='0'; i--)
		ndigit--;
	if (decpt >= 0 && decpt-ndigit > 4
	 || decpt < 0 && decpt < -3) { /* use E-style */
		decpt--;
		*p2++ = *p1++;
		*p2++ = _lc_radix;		/* INTL radix character */
		for (i=1; i<ndigit; i++)
			*p2++ = *p1++;
		*p2++ = 'e';
		if (decpt<0) {
			decpt = -decpt;
			*p2++ = '-';
		} else
			*p2++ = '+';
		*p2++ = decpt/10 + '0';
		*p2++ = decpt%10 + '0';
	} else {
		if (decpt<=0) {
			if (*p1!='0')
				*p2++ = _lc_radix;	/* INTL */
			while (decpt<0) {
				decpt++;
				*p2++ = '0';
			}
		}
		for (i=1; i<=ndigit; i++) {
			*p2++ = *p1++;
			if (i==decpt)
				*p2++ = _lc_radix;	/* INTL */
		}
		if (ndigit<decpt) {
			while (ndigit++<decpt)
				*p2++ = '0';
			*p2++ = _lc_radix;		/* INTL */
		}
	}
	if (p2[-1]==_lc_radix)				/* INTL */
		p2--;
	*p2 = '\0';
	return(buf);
}