with sign

getint2.c

int getint2(int *out) {
	register int s = 0;
	register int ch;
	ch = getchar();
	bool negative = false;
	while (ch < '0' || ch > '9') {
		if (ch == '-') {
			negative = true;
			ch = getchar();
			break;
		}
		ch = getchar();
	}
	while (ch >= '0' && ch <= '9') {
		s = s * 10 + ch - '0';
		ch = getchar();
	}
	*out = negative ? -s : s;
	return ch;
}