C++ 文件操作之配置文件读取

在项目应用时常常会涉及一些调参工作，如果项目封装成了.exe或者.dll，那么频繁调参多次编译是一件十分低效的事情，如果代码算法或者逻辑是一定的，那么参数完全可以通过读入配置文件来获取
之前在用C++ - opencv的yaml文件配置参数，但是后边参数导入时会出现异常情况，因此更换成 .txt \ .ini \ .config \ .info等格式，这些均为文本文件读取。

1. yaml的使用

在此处放一个opencv官网的例子吧

1.1 yaml写入

写入代码实现：

#include "opencv2/core.hpp"
#include <time.h>
using namespace cv;
int main(int, char** argv)
{//创建文件FileStorage fs("test.yml", FileStorage::WRITE);fs << "frameCount" << 5;time_t rawtime; time(&rawtime);fs << "calibrationDate" << asctime(localtime(&rawtime));Mat cameraMatrix = (Mat_<double>(3,3) << 1000, 0, 320, 0, 1000, 240, 0, 0, 1);Mat distCoeffs = (Mat_<double>(5,1) << 0.1, 0.01, -0.001, 0, 0);fs << "cameraMatrix" << cameraMatrix << "distCoeffs" << distCoeffs;fs << "features" << "[";for( int i = 0; i < 3; i++ ){int x = rand() % 640;int y = rand() % 480;uchar lbp = rand() % 256;fs << "{:" << "x" << x << "y" << y << "lbp" << "[:";for( int j = 0; j < 8; j++ )fs << ((lbp >> j) & 1);fs << "]" << "}";}fs << "]";fs.release();return 0;
}

写入结果：

%YAML:1.0
frameCount: 5
calibrationDate: "Fri Jun 17 14:09:29 2011\n"
cameraMatrix: !!opencv-matrixrows: 3cols: 3dt: ddata: [ 1000., 0., 320., 0., 1000., 240., 0., 0., 1. ]
distCoeffs: !!opencv-matrixrows: 5cols: 1dt: ddata: [ 1.0000000000000001e-01, 1.0000000000000000e-02,-1.0000000000000000e-03, 0., 0. ]
features:- { x:167, y:49, lbp:[ 1, 0, 0, 1, 1, 0, 1, 1 ] }- { x:298, y:130, lbp:[ 0, 0, 0, 1, 0, 0, 1, 1 ] }- { x:344, y:158, lbp:[ 1, 1, 0, 0, 0, 0, 1, 0 ] }

1.2 yaml读取

读取代码实现：

#include "opencv2/core.hpp"
#include <time.h>
using namespace cv;
int main(int, char** argv)
{    FileStorage fs2("test.yml", FileStorage::READ);//注意数据格式转换// first method: use (type) operator on FileNode.int frameCount = (int)fs2["frameCount"];String date;// second method: use FileNode::operator >>fs2["calibrationDate"] >> date;Mat cameraMatrix2, distCoeffs2;fs2["cameraMatrix"] >> cameraMatrix2;fs2["distCoeffs"] >> distCoeffs2;cout << "frameCount: " << frameCount << endl<< "calibration date: " << date << endl<< "camera matrix: " << cameraMatrix2 << endl<< "distortion coeffs: " << distCoeffs2 << endl;FileNode features = fs2["features"];FileNodeIterator it = features.begin(), it_end = features.end();int idx = 0;std::vector<uchar> lbpval;// iterate through a sequence using FileNodeIteratorfor( ; it != it_end; ++it, idx++ ){cout << "feature #" << idx << ": ";cout << "x=" << (int)(*it)["x"] << ", y=" << (int)(*it)["y"] << ", lbp: (";// you can also easily read numerical arrays using FileNode >> std::vector operator.(*it)["lbp"] >> lbpval;for( int i = 0; i < (int)lbpval.size(); i++ )cout << " " << (int)lbpval[i];cout << ")" << endl;}fs2.release();return 0;
}

2. ini文件读取

参考：https://linuxcpp.0voice.com/?id=75300
代码实现：

#include <iostream>
#include <fstream>
#include <string>
using namespace std;
int main()
{// 打开配置文件ifstream config_file("config.txt");if (!config_file.is_open()){cerr << "Failed to open config file." << endl;return -1;}// 逐行读取并解析数据string line;while (getline(config_file, line)){// 如果是注释或空行，则忽略if (line.empty() || line[0] == '#')continue;// 解析key-value对size_t pos = line.find('=');if (pos != string::npos){string key = line.substr(0, pos);string value = line.substr(pos + 1);cout << "Key: " << key << ", Value: " << value << endl;}}// 关闭文件config_file.close();return 0;
}