view Python/atof.c @ 51749:1408feec0084 3.0

Merged revisions 69798 via svnmerge from svn+ssh://pythondev@svn.python.org/python/branches/py3k ................ r69798 | benjamin.peterson | 2009-02-19 22:02:38 -0600 (Thu, 19 Feb 2009) | 13 lines Merged revisions 69769,69776 via svnmerge from svn+ssh://pythondev@svn.python.org/python/trunk ........ r69769 | georg.brandl | 2009-02-19 02:30:06 -0600 (Thu, 19 Feb 2009) | 1 line #5310, #3558: fix operator precedence table. ........ r69776 | georg.brandl | 2009-02-19 10:34:51 -0600 (Thu, 19 Feb 2009) | 2 lines #5317: update IronPython URL. ........ ................
author Benjamin Peterson <benjamin@python.org>
date Fri, 20 Feb 2009 04:05:32 +0000
parents 2dea40e40d9d
children fd25030223b0
line wrap: on
line source


/* Just in case you haven't got an atof() around...
   This one doesn't check for bad syntax or overflow,
   and is slow and inaccurate.
   But it's good enough for the occasional string literal... */

#include "pyconfig.h"

#include <ctype.h>

double atof(char *s)
{
	double a = 0.0;
	int e = 0;
	int c;
	while ((c = *s++) != '\0' && isdigit(c)) {
		a = a*10.0 + (c - '0');
	}
	if (c == '.') {
		while ((c = *s++) != '\0' && isdigit(c)) {
			a = a*10.0 + (c - '0');
			e = e-1;
		}
	}
	if (c == 'e' || c == 'E') {
		int sign = 1;
		int i = 0;
		c = *s++;
		if (c == '+')
			c = *s++;
		else if (c == '-') {
			c = *s++;
			sign = -1;
		}
		while (isdigit(c)) {
			i = i*10 + (c - '0');
			c = *s++;
		}
		e += i*sign;
	}
	while (e > 0) {
		a *= 10.0;
		e--;
	}
	while (e < 0) {
		a *= 0.1;
		e++;
	}
	return a;
}