常用函数总结

//统计文件中的行数，即数据文件中数据数目
int count(string file)
{
	cout << "数据计数中..." << endl;
	ifstream infile;
	infile.open(file.data());   //将文件流对象与文件连接起来 
	assert(infile.is_open());   //若失败,则输出错误消息,并终止程序运行 

	string s;
	vector<string> ve;
	int num = 0;
	while (getline(infile, s))
	{
		num++;
	}
	infile.close();  //关闭文件输入流 
	cout << "文件计数完毕..." << endl;
	return num;
}

//从一个数据文件中复制length个数据到新文件中
void copyData(string file, int length)
{
	std::cout << "读取数据中..." << endl;
	ifstream infile;
	infile.open(file.data());   //将文件流对象与文件连接起来 
	assert(infile.is_open());   //若失败,则输出错误消息,并终止程序运行 

	string s;
	//char str;
	vector<string> ve;
	vector<Point> num;
	int aa = length;
	while (aa)
	{
		Point p;
		int i = 0;
		string num_s = "";
		getline(infile, s);
		while (s[i] != ' ')
		{
			num_s += s[i];
			i++;
		}
		p.x = str2num(num_s);
		i++;
		num_s = "";
		while (s[i] != ' ')
		{
			num_s += s[i];
			i++;
		}
		p.y = str2num(num_s);
		i++;
		num_s = "";
		while (i <= s.size())
		{
			num_s += s[i];
			i++;
		}
		p.z = str2num(num_s);
		num.push_back(p);
		aa--;
	}

	infile.close();             //关闭文件输入流 
	std::cout << "读取文件完毕..." << endl;

	std::cout << "写入数据..." << endl;

	ofstream fout("data.txt");
	for (int i = 0; i < length; i++)
	{
		fout << num[i].x << " " << num[i].y << " " << num[i].z << endl;
	}
	std::cout << "写入数据完毕..." << endl;
	fout.close();
}

//新建一个文件，写入数据
//格式为：  x y z
void write_txt(vector<Point>num)
{
	cout << "写入数据..." << endl;
	ofstream fout("data.txt");
	for (int i = 0; i <num.size(); i++)
	{
		fout << num[i].x << " " << num[i].y << " " << num[i].z << endl;
	}
	std::cout << "写入数据完毕..." << endl;
	fout.close();
}

//分别找出点云数据x、y、z的最大和最小值
void Maximum_value(vector<Point>num)
{
	Xmax = num[0].x;  Xmin = num[0].x;
	Ymax = num[0].y; Ymin = num[0].y;
	Zmax = num[0].z; Zmin = num[0].z;
	for (int i = 0; i < num.size(); i++)
	{
		if (Xmax < num[i].x) Xmax = num[i].x;
		if (Xmin > num[i].x) Xmin = num[i].x;
		if (Ymax < num[i].y) Ymax = num[i].y;
		if (Ymin > num[i].y) Ymin = num[i].y;
		if (Zmax < num[i].z) Zmax = num[i].z;
		if (Zmin > num[i].z) Zmin = num[i].z;
	}
	std::cout << "Xmax:  " << Xmax << "     Xmin:  " << Xmin << endl;
	std::cout << "Ymax:  " << Ymax << "     Ymin:  " << Ymin << endl;
	std::cout << "Zmax:  " << Zmax << "     Zmin:  " << Zmin << endl;
}

// 字符串转换为数字，需要有文件 #include <sstream>
int str2num(const string str)
{
	stringstream ss(str);
	int num;
	ss >> num;
	return num;
}