将文件中的代码转换成c++代码，功能不变

将给定的Python代码转换为C++代码需要考虑以下几个方面：

1. **库的替换**：OpenCV在Python和C++中的API有差异，需要进行相应的调整。
2. **语法差异**：Python和C++在语法上有显著不同，例如循环、条件语句等。
3. **数据类型的管理**：C++是静态类型语言，需要显式声明变量类型。
4. **错误处理**：C++通常使用异常处理机制来处理错误。

以下是将给定的Python代码转换为C++代码的示例：

#include <opencv2/opencv.hpp>
#include <iostream>
#include <vector>
#include <cmath>

using namespace cv;
using namespace std;

// 定义常量
const int jifen = 5;
const int daodianju = 3;
const float feichezhanbi = 0.73;
const int yuanhuanyuzhi = 40;
const int yuanhuanjingdu = 10;
const int kuanzeng = 90;
const int kuanzeng2 = 70;
const int CAMERA_H = 60;
const int CAMERA_W = 94;
const int OUT_H = 60;
const int OUT_W = 94;

// 全局变量
int shiziji = 0;
int banmasign = 0;

// 结构体定义
struct Up {
    Point dian;
    int que;
};

// 图像二值化
Mat er_zhi(Mat imgxiu) {
    try {
        Mat imgCvt, imgTemp, imgThr;
        cvtColor(imgxiu, imgCvt, COLOR_BGR2GRAY);
        GaussianBlur(imgCvt, imgTemp, Size(5, 5), 0);
        threshold(imgTemp, imgThr, 0, 255, THRESH_BINARY + THRESH_OTSU);
        if (imgThr.empty()) {
            throw runtime_error("Thresholding failed, possibly due to invalid image data.");
        }
        return imgThr;
    } catch (const exception& e) {
        cerr << "An error occurred: " << e.what() << endl;
        return Mat();
    }
}

// 画出赛道两侧线和中线
void che_dao_xian(Mat imgEr, Mat& imgSour) {
    vector<Up> zuoDao, youDao, zhongXian;
    int shizipan = 0, yuanhuanzuosign = 0, yuanhuanyousign = 0;
    vector<Point> yuanhuanweidian(4, Point(0, 0));
    int high = static_cast<int>(imgEr.rows * feichezhanbi);

    // 获取每一列白色点数据
    vector<int> lieBais(imgEr.cols, 0);
    for (int x = 0; x < imgEr.cols; ++x) {
        for (int y = high - 1; y >= 0; --y) {
            if (imgEr.at<uchar>(y, x) != 0) {
                lieBais[x]++;
            } else {
                break;
            }
        }
    }

    // 寻找左右最长白条
    int maxzuo[] = {0, 0};
    int maxyou[] = {0, 0};
    for (int a = 0; a < lieBais.size(); ++a) {
        if (lieBais[a] > maxzuo[1]) {
            maxzuo[0] = a;
            maxzuo[1] = lieBais[a];
        }
    }
    for (int a = lieBais.size() - 1; a >= 0; --a) {
        if (lieBais[a] > maxyou[1]) {
            maxyou[0] = a;
            maxyou[1] = lieBais[a];
        }
    }

    // 找车道线
    int chushi = 0, chuju = 0, shiziZuox = 0, shiziYoux = 0;
    for (int y = high - 1; y > high - maxzuo[1]; --y) {
        int zuox = maxzuo[0];
        for (int x = maxzuo[0]; x >= 0; --x) {
            if (imgEr.at<uchar>(y, x) != 0 && imgEr.at<uchar>(y, x - 1) == 0) {
                if (!zuoDao.empty()) {
                    double dist = norm(Point(x, y) - zuoDao.back().dian);
                    if (dist <= daodianju) {
                        zuoDao.push_back({Point(x, y), 0});
                        zuox = x;
                        break;
                    }
                } else {
                    zuoDao.push_back({Point(x, y), 0});
                    zuox = x;
                    break;
                }
            } else if (imgEr.at<uchar>(y, x) != 0 && imgEr.at<uchar>(y, x - 1) != 0 && imgEr.at<uchar>(y, x - 2) != 0) {
                shiziZuox++;
                if (x - 3 == 0) {
                    break;
                }
            }
        }

        int tempx = maxyou[0];
        for (int x = maxyou[0] + 5; x < imgEr.cols; ++x) {
            if (imgEr.at<uchar>(y, x) != 0 && imgEr.at<uchar>(y, x + 1) == 0) {
                if (!youDao.empty()) {
                    double dist = norm(Point(x, y) - youDao.back().dian);
                    if (dist <= daodianju) {
                        youDao.push_back({Point(x, y), 0});
                        tempx = x;
                        break;
                    }
                } else {
                    youDao.push_back({Point(x, y), 0});
                    tempx = x;
                    break;
                }
            } else if (imgEr.at<uchar>(y, x) != 0 && imgEr.at<uchar>(y, x + 1) != 0 && imgEr.at<uchar>(y, x + 2) != 0) {
                shiziYoux++;
                if (x + 3 == imgEr.cols - 1) {
                    break;
                }
            }
        }

        if (chuju == 0) {
            chuju = tempx - zuox;
        }

        if (abs(shiziZuox - maxzuo[0]) <= 5 && abs(imgEr.cols - maxyou[0] + 4 - shiziYoux) <= 5) {
            shizipan = 1;
        }
    }

    // 判断圆环存在否，及其位置
    if (abs(static_cast<int>(zuoDao.size()) - static_cast<int>(youDao.size())) >= yuanhuanyuzhi) {
        int ji1 = 0, ji2 = 0, signs = 0;

        // 左圆环
        if (zuoDao.size() < youDao.size()) {
            int zuominx = 999999;
            for (const auto& point : zuoDao) {
                if (zuominx > point.dian.x) {
                    zuominx = point.dian.x;
                }
            }
            for (size_t n = 0; n < youDao.size(); ++n) {
                signs = 0;
                for (int x = youDao[n].dian.x; x > max(zuominx - 5, 1); --x) {
                    if (imgEr.at<uchar>(youDao[n].dian.y, x) != 0 && imgEr.at<uchar>(youDao[n].dian.y, x - 1) == 0) {
                        if (yuanhuanyousign == 1 && ji1 >= 5) {
                            yuanhuanyousign = 2;
                            yuanhuanweidian[1] = Point(youDao[n - 5].dian.x - kuanzeng, youDao[n - 5].dian.y);
                            ji1 = 0;
                        } else if (yuanhuanyousign == 3 && ji1 >= 5) {
                            yuanhuanyousign = 4;
                            ji1 = 0;
                            break;
                        }
                        signs = 1;
                        ji1++;
                        ji2 = 0;
                    }
                }
                if (signs == 0) {
                    if (yuanhuanyousign == 0 && ji2 >= 5) {
                        yuanhuanyousign = 1;
                        yuanhuanweidian[0] = Point(youDao[n - 5].dian.x - kuanzeng, youDao[n - 5].dian.y);
                        ji2 = 0;
                    } else if (yuanhuanyousign == 2 && ji2 >= 5) {
                        yuanhuanyousign = 3;
                        ji2 = 0;
                    }
                    ji2++;
                    ji1 = 0;
                }
            }
        }

        // 右圆环
        else {
            int youmaxx = 0;
            for (const auto& point : youDao) {
                if (youmaxx < point.dian.x) {
                    youmaxx = point.dian.x;
                }
            }
            for (size_t n = 0; n < zuoDao.size(); ++n) {
                signs = 0;
                for (int x = zuoDao[n].dian.x; x < youmaxx; ++x) {
                    if (imgEr.at<uchar>(zuoDao[n].dian.y, x) != 0 && imgEr.at<uchar>(zuoDao[n].dian.y, x + 1) == 0) {
                        if (yuanhuanzuosign == 1 && ji1 >= yuanhuanjingdu) {
                            yuanhuanzuosign = 2;
                            yuanhuanweidian[1] = Point(zuoDao[n - 5].dian.x + kuanzeng2, zuoDao[n - 5].dian.y);
                            ji1 = 0;
                        } else if (yuanhuanzuosign == 3 && ji1 >= yuanhuanjingdu) {
                            yuanhuanzuosign = 4;
                            ji1 = 0;
                            break;
                        }
                        signs = 1;
                        ji1++;
                        ji2 = 0;
                    }
                }
                if (signs == 0) {
                    if (yuanhuanzuosign == 0 && ji2 >= yuanhuanjingdu) {
                        yuanhuanzuosign = 1;
                        yuanhuanweidian[0] = Point(zuoDao[n - 5].dian.x + kuanzeng2 + 10, zuoDao[n - 5].dian.y);
                        ji2 = 0;
                    } else if (yuanhuanzuosign == 2 && ji2 >= yuanhuanjingdu) {
                        yuanhuanzuosign = 3;
                        ji2 = 0;
                    }
                    ji2++;
                    ji1 = 0;
                }
            }
        }

        // 圆环判断
        if (yuanhuanzuosign == 4) {
            putText(imgSour, "right circular", Point(10, 40), FONT_HERSHEY_COMPLEX, 0.7, Scalar(0, 0, 255), 2);
            for (int n = 0; n < 2; ++n) {
                line(imgSour, Point(imgEr.cols - 1, yuanhuanweidian[n].y), yuanhuanweidian[n], Scalar(255, 0, 255), 3.5);
            }
        } else if (yuanhuanyousign == 4) {
            putText(imgSour, "left circular", Point(10, 40), FONT_HERSHEY_COMPLEX, 0.7, Scalar(0, 0, 255), 2);
            for (int n = 0; n < 2; ++n) {
                line(imgSour, Point(0, yuanhuanweidian[n].y), yuanhuanweidian[n], Scalar(255, 0, 255), 3.5);
            }
        }
    }

    // 找中线
    size_t sizes = min(zuoDao.size(), youDao.size());
    for (size_t n = 0; n < sizes; ++n) {
        if (zuoDao[n].que == 0 && youDao[n].que == 0) {
            int zhongx = (zuoDao[n].dian.x + youDao[n].dian.x) / 2;
            int zhongy = (zuoDao[n].dian.y + youDao[n].dian.y) / 2;
            if (zhongXian.empty() || (abs(zhongx - zhongXian.back().dian.x) <= daodianju && abs(zhongy - zhongXian.back().dian.y) >= 2)) {
                zhongXian.push_back({Point(zhongx, zhongy), 0});
            }
        }
    }

    // 画出中线
    for (size_t n = 0; n < zhongXian.size() - 1; ++n) {
        circle(imgSour, zhongXian[n].dian, 2, Scalar(0, 255, 0), -1);
        line(imgSour, zhongXian[n].dian, zhongXian[n + 1].dian, Scalar(0, 255, 0), 4);
    }

    // 画出车道线
    for (const auto& point : zuoDao) {
        circle(imgSour, point.dian, 2, Scalar(255, 0, 0), -1);
    }
    for (const auto& point : youDao) {
        circle(imgSour, point.dian, 2, Scalar(0, 0, 255), -1);
    }
}

int main() {
    string video_file = "playground.mp4";
    VideoCapture cap(video_file);
    if (!cap.isOpened()) {
        cerr << "Error opening video file." << endl;
        return -1;
    }

    while (cap.isOpened()) {
        Mat frame, frame2, f;
        if (!cap.read(frame)) {
            break;
        }

        try {
            frame2 = er_zhi(frame);
            che_dao_xian(frame2, frame);
            imshow("Frame", frame);
            if (waitKey(1) & 0xFF == 'q') {
                break;
            }
        } catch (const exception& e) {
            cerr << "Exception: " << e.what() << endl;
        }
    }

    cap.release();
    destroyAllWindows();
    return 0;
}

### 主要变化点：
1. **库的导入**：从`#include <opencv2/opencv.hpp>`开始，引入了必要的OpenCV头文件。
2. **常量和全局变量**：直接用`const`关键字定义常量，并初始化全局变量。
3. **函数定义**：将Python的函数转换为C++的函数，注意参数和返回值类型的定义。
4. **数据类型**：所有变量都显式声明了类型。
5. **循环和条件语句**：C++中的循环和条件语句与Python类似，但需要注意语法上的细微差别。
6. **错误处理**：使用`try-catch`块来捕获和处理异常。

希望这段C++代码能够满足你的需求。如果有任何问题或需要进一步优化，请告诉我！