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v0.5.1
https://github.com/python/cpython
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Tip revision: fdbdcfe020f8b55a1893d1185d7a250bce12625e authored by Benjamin Peterson on 30 June 2014, 01:58:16 UTC
bump to 2.7.8
Tip revision: fdbdcfe
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 "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;
}
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