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v0.5.1
https://github.com/python/cpython
09 December 2020, 11:06:31 UTC
Revision cf744da03be452ea69316838f08afbd4ba464be1 authored by Georg Brandl on 05 March 2011, 13:57:44 UTC, committed by Georg Brandl on 05 March 2011, 13:57:44 UTC 
Close legacy-trunk branch.
1 parent b847079
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Tip revision: cf744da03be452ea69316838f08afbd4ba464be1 authored by Georg Brandl on 05 March 2011, 13:57:44 UTC
Close legacy-trunk branch.
Tip revision: cf744da
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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