https://github.com/python/cpython
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Tip revision: c2f86d86e6c8f5fd1ef602128b537a48f3f5c063 authored by Benjamin Peterson on 19 October 2019, 18:38:44 UTC
Empty blurb file for 2.7.17.
Tip revision: c2f86d8
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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