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v0.8.1
https://github.com/python/cpython
09 December 2020, 11:06:31 UTC
Revision 5f55933b3a78b7f3557ac81a2411a1b50bffab33 authored by Georg Brandl on 05 March 2011, 13:54:46 UTC, committed by Georg Brandl on 05 March 2011, 13:54:46 UTC 
Close 2.1 branch.
1 parent a97ca43
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Tip revision: 5f55933b3a78b7f3557ac81a2411a1b50bffab33 authored by Georg Brandl on 05 March 2011, 13:54:46 UTC
Close 2.1 branch.
Tip revision: 5f55933
atof.c 

/* 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 "config.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;
}
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