function_strmid

char * strmid(register char * string, register int start, register int len)
{
	int string_len = strlen(string) > len ? len : strlen(string);
	register char * str = (char *)calloc(sizeof(char), string_len + sizeof(int));
	for (int i = start; i <= string_len; i++)
		str[i - start] = string[i];
	return str;
}