1#define _GNU_SOURCE
 2#include <stdlib.h>
 3#include <stdio.h>
 4#include <string.h>
 5
 6char *fcvt(double x, int n, int *dp, int *sign)
 7{
 8	char tmp[1500];
 9	int i, lz;
10
11	if (n > 1400U) n = 1400;
12	sprintf(tmp, "%.*f", n, x);
13	i = (tmp[0] == '-');
14	if (tmp[i] == '0') lz = strspn(tmp+i+2, "0");
15	else lz = -(int)strcspn(tmp+i, ".");
16
17	if (n<=lz) {
18		*sign = i;
19		*dp = 1;
20		if (n>14U) n = 14;
21		return "000000000000000"+14-n;
22	}
23
24	return ecvt(x, n-lz, dp, sign);
25}