int strlen(char *str)
{
	int len = 0;
	while (str[len] != '\0')len++;
	return len;
}

int strcmp(const char *str1, const char *str2)
{
	int len1 = strlen(str1);
	int len2 = strlen(str2);
	int i = 0;
	while (str1[i] == str2[i] && i < len1 && i < len2)
		i++;
	if (i == len1) {
		if (i == len2) return 0;
		else return -1;
	}
	else if (i == len2)return 1;
	else if (str1[i] < str2[i]) return -1;
	else return 1;
}

void strcopy(char *str1, const char *str2)
{
	int len = strlen(str2);
	for (int i = 0; i < len; i++)
		str1[i] = str2[i];
	str1[len] = '\0';
}