改写const auto& file : std::filesystem::directory_iterator(folder_path)
时间: 2024-01-11 09:03:29 浏览: 34
我理解您的问题是如何改写“const auto”语法。在C++中,使用“auto”关键字可以让编译器自动推导数据类型,而“const”关键字则表示该变量的值不能被修改。因此,“const auto”可以让编译器自动推导数据类型的同时又保证其值不会被修改。
如果要改写“const auto”,可以根据具体的情况来使用其他类型声明符。例如,如果您希望指定变量类型为整数类型,并且该变量的值不能被修改,可以使用“const int”语法。如果您希望推导变量类型为指针类型,并且该指针指向的值不能被修改,则可以使用“const auto *”语法。
需要注意的是,在改写“const auto”时,要保证新的类型声明符能够正确地描述变量的类型和属性,以避免可能发生的类型错误和逻辑错误。
相关问题
#include<iostream> #include<ctime> #include<chrono> #include<string> #include<filesystem> #include<fstream> #include<sstream> #include<thread> #include<boost/filesystem.hpp> const uintmax_t MAX_LOGS_SIZE = 10ull * 1024ull * 1024ull * 1024ull; //const uintmax_t MAX_LOGS_SIZE = 10ull; void create_folder(std::string folder_name) { boost::filesystem::create_directory(folder_name); std::string sub_foldername=folder_name+"/logs_ros"; boost::filesystem::create_directory(sub_foldername); } std::string get_current_time() { auto now = std::chrono::system_clock::now(); std::time_t now_c = std::chrono::system_clock::to_time_t(now); std::tm parts = *std::localtime(&now_c); char buffer[20]; std::strftime(buffer, sizeof(buffer), "%Y-%m-%d-%H-%M", &parts); return buffer; } void check_logs_size() { std::string logs_path = "/home/sage/logs/"; boost::filesystem::path logs_dir(logs_path); std::uintmax_t total_size = 0; for (const auto& file : boost::filesystem::recursive_directory_iterator(logs_dir)) { if (boost::filesystem::is_regular_file(file)) { total_size += boost::filesystem::file_size(file); } } if (total_size > MAX_LOGS_SIZE) { boost::filesystem::path earliest_dir; std::time_t earliest_time = std::time(nullptr); for (const auto& dir : boost::filesystem::directory_iterator(logs_dir)) { if (boost::filesystem::is_directory(dir)) { std::string dir_name = dir.path().filename().string(); std::tm time_parts = {}; std::istringstream ss(dir_name); std::string part; std::getline(ss, part, '-'); time_parts.tm_year = std::stoi(part) - 1900; std::getline(ss, part, '-'); time_parts.tm_mon = std::stoi(part) - 1; std::getline(ss, part, '-'); time_parts.tm_mday = std::stoi(part); std::getline(ss, part, '-'); time_parts.tm_hour = std::stoi(part); std::getline(ss, part, '-'); time_parts.tm_min = std::stoi(part); std::time_t dir_time = std::mktime(&time_parts); if (dir_time < earliest_time) { earliest_time = dir_time; earliest_dir = dir.path(); } } } if (!earliest_dir.empty()) { boost::filesystem::remove_all(earliest_dir); } } } int main() { std::string logs_path = "/home/sage/logs/"; while (true) { std::chrono::system_clock::time_point now = std::chrono::system_clock::now(); std::time_t now_c = std::chrono::system_clock::to_time_t(now); std::tm parts = *std::localtime(&now_c); if (parts.tm_min % 10 == 0) { std::string folder_name = logs_path + get_current_time(); create_folder(folder_name); } check_logs_size(); std::this_thread::sleep_for(std::chrono::minutes(1)); } return 0; }修改为ros节点
好的,我可以帮您将这段代码修改为ROS节点。首先,我们需要包含ROS所需的头文件,例如:
```cpp
#include <ros/ros.h>
```
然后,我们需要在main函数中初始化ROS节点:
```cpp
int main(int argc, char** argv) {
ros::init(argc, argv, "log_manager_node");
ros::NodeHandle nh;
// ...
return 0;
}
```
接下来,我们需要将定时任务和日志删除任务分别封装为ROS的定时器和服务。在main函数中,我们可以这样定义一个定时器:
```cpp
ros::Timer timer = nh.createTimer(ros::Duration(60.0), timerCallback);
```
其中,`timerCallback` 是一个你需要定义的回调函数,它将在每隔60秒被定时器调用一次。在回调函数中,你可以像之前的代码一样执行创建文件夹和检查日志大小的任务。
同样地,我们可以定义一个ROS服务来执行删除任务。我们需要在main函数中定义一个服务服务器:
```cpp
ros::ServiceServer delete_logs_server = nh.advertiseService("delete_logs", deleteLogsCallback);
```
其中,`deleteLogsCallback` 是一个你需要定义的服务回调函数,它将在收到删除日志服务请求时被调用。在回调函数中,你可以像之前的代码一样执行删除日志的任务。
最后,完整的ROS节点代码如下:
```cpp
#include <ros/ros.h>
#include <ctime>
#include <chrono>
#include <string>
#include <filesystem>
#include <fstream>
#include <sstream>
#include <thread>
#include <boost/filesystem.hpp>
const uintmax_t MAX_LOGS_SIZE = 10ull * 1024ull * 1024ull * 1024ull;
void create_folder(std::string folder_name) {
boost::filesystem::create_directory(folder_name);
std::string sub_foldername = folder_name + "/logs_ros";
boost::filesystem::create_directory(sub_foldername);
}
std::string get_current_time() {
auto now = std::chrono::system_clock::now();
std::time_t now_c = std::chrono::system_clock::to_time_t(now);
std::tm parts = *std::localtime(&now_c);
char buffer[20];
std::strftime(buffer, sizeof(buffer), "%Y-%m-%d-%H-%M", &parts);
return buffer;
}
void check_logs_size() {
std::string logs_path = "/home/sage/logs/";
boost::filesystem::path logs_dir(logs_path);
std::uintmax_t total_size = 0;
for (const auto& file : boost::filesystem::recursive_directory_iterator(logs_dir)) {
if (boost::filesystem::is_regular_file(file)) {
total_size += boost::filesystem::file_size(file);
}
}
if (total_size > MAX_LOGS_SIZE) {
boost::filesystem::path earliest_dir;
std::time_t earliest_time = std::time(nullptr);
for (const auto& dir : boost::filesystem::directory_iterator(logs_dir)) {
if (boost::filesystem::is_directory(dir)) {
std::string dir_name = dir.path().filename().string();
std::tm time_parts = {};
std::istringstream ss(dir_name);
std::string part;
std::getline(ss, part, '-');
time_parts.tm_year = std::stoi(part) - 1900;
std::getline(ss, part, '-');
time_parts.tm_mon = std::stoi(part) - 1;
std::getline(ss, part, '-');
time_parts.tm_mday = std::stoi(part);
std::getline(ss, part, '-');
time_parts.tm_hour = std::stoi(part);
std::getline(ss, part, '-');
time_parts.tm_min = std::stoi(part);
std::time_t dir_time = std::mktime(&time_parts);
if (dir_time < earliest_time) {
earliest_time = dir_time;
earliest_dir = dir.path();
}
}
}
if (!earliest_dir.empty()) {
boost::filesystem::remove_all(earliest_dir);
}
}
}
void timerCallback(const ros::TimerEvent& event) {
std::string logs_path = "/home/sage/logs/";
std::chrono::system_clock::time_point now = std::chrono::system_clock::now();
std::time_t now_c = std::chrono::system_clock::to_time_t(now);
std::tm parts = *std::localtime(&now_c);
if (parts.tm_min % 10 == 0) {
std::string folder_name = logs_path + get_current_time();
create_folder(folder_name);
}
check_logs_size();
}
bool deleteLogsCallback(std_srvs::Empty::Request& req, std_srvs::Empty::Response& res) {
std::string logs_path = "/home/sage/logs/";
boost::filesystem::path logs_dir(logs_path);
boost::filesystem::remove_all(logs_dir);
return true;
}
int main(int argc, char** argv) {
ros::init(argc, argv, "log_manager_node");
ros::NodeHandle nh;
ros::Timer timer = nh.createTimer(ros::Duration(60.0), timerCallback);
ros::ServiceServer delete_logs_server = nh.advertiseService("delete_logs", deleteLogsCallback);
ros::spin();
return 0;
}
```
在这个节点中,我们定义了一个名为 `log_manager_node` 的ROS节点,并在其中实现了一个定时器和一个服务。定时器每隔60秒检查一次日志大小并创建新的日志文件夹,服务则用于删除所有日志文件。
namespace fs = std::filesystem;这句话我这里显示错误
如果您的编译器不支持 C++17,可能会出现该错误。在这种情况下,您需要使用以下方法来遍历目录:
```c++
#include <iostream>
#include <opencv2/opencv.hpp>
#include <experimental/filesystem>
namespace fs = std::experimental::filesystem;
using namespace std;
using namespace cv;
int main(int argc, char** argv)
{
// 指定文件夹路径
string folder_path = "your/folder/path";
for (const auto& file : fs::directory_iterator(folder_path))
{
if (file.path().extension() == ".jpg" || file.path().extension() == ".png")
{
// 读取图片
Mat img = imread(file.path().string());
// 显示图片
imshow("Image", img);
waitKey(0);
}
}
return 0;
}
```
这里我们使用 `std::experimental::filesystem` 命名空间代替 `std::filesystem` 命名空间。这个命名空间在 C++17 之前是实验性的,因此被称为实验性文件系统库。如果您的编译器支持 C++17,则应该使用 `std::filesystem` 命名空间。