char_to_double.c

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#include "config.h"
#include "char_to_double.h"

#include <string.h>
#include <math.h>

#include "len.h"
#include "char_to_int.h"

#ifndef MIN
#       define MIN(a, b) (a > b ? b : a)
#endif

short int check_double(const char *s, int len)
{
        if(s == NULL) return 0;
        if(len == -1) len = str_len(s);

        char digits[] = "0123456789";
        short dot = 1;
        int i;
        for(i = 0; i < len; i++)
        {
                if(i == 0 && s[i] == '-') continue;
                if(dot > 0 && s[i] == '.')
                {
                        dot--;
                        continue;
                }
                else if(strchr(digits, s[i]) != NULL)
                        continue;
                else
                        return 0;
        }
        return 1;
}

long double char_to_double(const char *s, int len)
{
        if(s == NULL) return 0;
        if(len == -1) len = str_len(s);

        int k = 1;
        if(s[0] == '-')
        {
          k = -1;
          s++;
          len--;
        }

        int i = MIN(_len(s, '.'), len);
        int j = len - i - 1;
        
        long double res = char_to_int(s, i, 10);
        if(j > 0)
                res += char_to_int(s + i + 1, j, 10) / pow(10, j);

        return res * k;
}