C++ 写入数据到.txt文件 从.txt文件读取数据 string字符串分割

将数据写入到.txt文件

//将数据写入到.txt文件
	vector quad_pts;
	quad_pts.push_back(Point2f(-602.935, 464.887));
	quad_pts.push_back(Point2f(-401.548, 477.997));
	quad_pts.push_back(Point2f(-1346.625, 261.575));
	quad_pts.push_back(Point2f(-129.836, 283.220));

	ofstream f1("Points.txt");//#include 
	char savePoints[100];//字符数组
	strcpy_s(savePoints, "quad_pts");
	f1 << savePoints << endl;
	for (int i = 0; i < quad_pts.size(); i++)
	{
		sprintf_s(savePoints, "Px%fy%f", quad_pts[i].x, quad_pts[i].y);
		f1 << savePoints << endl;
	}

将.txt文件数据读入到C++

//从.txt读入数据
	ifstream myFile;
	myFile.open("Points.txt");
	char output[100];
	if (myFile.is_open()) 
	{
		while (!myFile.eof()) 
		{
			myFile >> output;
			cout << output << endl;
		}
	}
	myFile.close();

得到两个标记字符串之间的那部分字符串

std::string cf_getMiddleStr(std::string srcStr, std::string StartMarkStr, std::string EndMarkStr)
{
	size_t startPos, endPos, length;
	startPos = srcStr.find(StartMarkStr, 0);
	endPos = srcStr.find(EndMarkStr, 0);
	length = endPos - startPos - StartMarkStr.size();
	std::string resStr = srcStr.substr(startPos + StartMarkStr.size(), length);//第二个参数表示长度
	return resStr;
}

得到标记字符串之前的那部分字符串

std::string cf_getStartStr(std::string srcStr, std::string EndMarkStr)
{
	size_t  endPos;
	endPos = srcStr.find(EndMarkStr, 0);
	std::string resStr = srcStr.substr(0, endPos);
	return resStr;
}

得到标记字符串之后的那部分字符串

std::string cf_getEndStr(std::string srcStr, std::string StartMarkStr)
{
	size_t startPos, length;
	startPos = srcStr.find(StartMarkStr, 0);
	length = srcStr.size() - startPos - StartMarkStr.size();
	std::string resStr = srcStr.substr(startPos + StartMarkStr.size(), length);
	return resStr;
}