I need to Build the Open DNP3 Lib but the problem coz there is a lot of .cpp and .h files in the library and I don't know how the add the lib to a Console C++ Project and build it
Iam a beginner in C++ and any thing will help me ; so fell free to leave any comment if you don't know the exact answer
I wrote a program in both C++ and Java to print "Hello World" 100,000 times, but I noticed that the C++ code takes too long compared to the Java code; The Java code takes about 6 seconds averagely and the C++ code takes about 18 seconds averagely, both run from the command line; Can someone please explain why, thanks.
The name of the program is first.java and first.cpp for Java and C++ respectively I used: java first.java; and first.exe; both from the command line
g++ --version g++ (Rev6, Built by MSYS2 project) 11.2.0
java --version java 13.0.2, 2020-01-14
Java Code
class first {
public static void main(String... args) {
long start = System.currentTimeMillis();
for (int i = 0; i < 100000; i++) {
System.out.println("Hello World");
}
long end = System.currentTimeMillis();
long dur = end - start;
System.out.println(dur / 1000);
}
}
C++ Code
#include <iostream>
#include <string>
#include <chrono>
using namespace std;
int main()
{
auto start = std::chrono::system_clock::now();
for (int i = 0; i < 100000; i++)
{
cout << "Hello World" << endl;
}
auto end = std::chrono::system_clock::now();
std::chrono::duration<double> elapsed_seconds = end - start;
cout << elapsed_seconds.count() << endl;
}
i have a Node template class in one "Node.cpp" and included in file "List.cpp" and List template class i have to create a traverse function which is friend to the List class to traverse all the node in a List but facing an error here is my error proner
template<typename T>
class List{
private:
Node<T> *headNode;
Node<T> *currentNode;
Node<T> *lastCurrentNode;
int size;
public:
List();
void add(T);
T get();
bool next();
friend void traverse(List<T>); // **there is an issue**
};
template <typename T>
void traverse(List <T>list)
{
Node<T> *savedCurrentNode = new Node<T>();
list.currentNode = list.headNode;
for(int i=1; list.next(); i++)
{
cout << "\n Element " << i << " " << list.get();
}
list.currentNode = savedCurrentNode;
}
i am a bigner and try to implement using templates but stuck into a problem now i have no idea how to solve this
I am writing an allocator (for simplicity, let's assume nothing fails or throws):
struct AllocationHeader
{
std::size_t size;
std::size_t align;
};
void *aligned_allocate(std::size_t requested_size, std::size_t alignment)
{
constexpr auto header_size = sizeof(AllocationHeader);
const auto total_size = header_size + requested_size + alignment;
auto alloced_ptr = ::new unsigned char[total_size];
::new (alloced_ptr) AllocationHeader{requested_size, alignment};
auto ret_ptr = static_cast<void *>(alloced_ptr + header_size);
auto remaining_size = total_size - header_size;
return std::align(alignment, requested_size, ret_ptr, remaining_size);
}
When I deallocate I want to recover the planted metadata
void aligned_deallocate(void *ptr)
{
constexpr auto header_size = sizeof(AllocationHeader);
// surely this is wrong
auto header_start = reinterpret_cast<unsigned char *>(ptr) - header_size;
auto header = reinterpret_cast<AllocationHeader *>(header_start);
do_something_with(header->size, header->align);
// rest of deallocation...
}
But surely the conversion back to AllocationHeader is wrong. The original align could in theory be anything (assuming power of 2) including > std::max_align_t.
So how do I portably recover how much std::align() shifted the pointer by? I'm limited to C++11.
EDIT:
I suppose I can do the shifting first:
void *aligned_allocate(std::size_t requested_size, std::size_t alignment)
{
constexpr auto header_size = sizeof(AllocationHeader);
const auto total_size = header_size + requested_size + alignment;
auto alloced_ptr = ::new unsigned char[total_size];
auto ret_ptr = static_cast<void *>(alloced_ptr + header_size);
auto remaining_size = total_size - header_size;
std::align(alignment, requested_size, ret_ptr, remaining_size);
::new (reinterpret_cast<unsigned char *>(ret_ptr) - header_size) AllocationHeader{requested_size, alignment};
return ret_ptr;
}
But then AllocationHeader may constructed misaligned...
I am trying the socketIO C++ client ; but i dont know how to use certificates . The SocketIO server needs valid certificate to answer Has someone managed to do it ? There is no documentation at all ... Thanks
Just a general question but I was wondering if you delete the outer dynamic arrays data, will the inner dynamic arrays be deleted as well?
I did do it in a personal project, but I'm just unsure if it deleted the inner dynamic array.
I have a really simple file, and I keep getting an error on it: IRequestFrame.h:20:65: error: expected class-name before ‘{’ token And I've been trying to find the problem all day, but I can;t find it. I keep checking but it looks to me that I did everything right... But computer says no.
This is the file (without the namespaces):
#ifndef SRC_POWERSOFT_KSERIES_MESSAGE_IREQUESTFRAME_H_
#define SRC_POWERSOFT_KSERIES_MESSAGE_IREQUESTFRAME_H_
#include "IFrame.h"
#include "../../serde/ISerializable.h"
#include "../packet/IRequestPacket.h"
namespace amp {
namespace kseries {
namespace message {
namespace frame {
class IRequestFrame: public IFrame, public amp::kseries::serde::ISerializable {
// ^ position of error
public:
virtual std::size_t serializeTo(char* const buffer, std::size_t buff_size) = 0;
virtual packet::IRequestPacket* getPacket() const = 0;
virtual ~IRequestFrame();
};
} // frame
} // message
} /* namespace kseries */
} /* namespace amp */
#endif /* SRC_POWERSOFT_KSERIES_MESSAGE_IREQUESTFRAME_H_ */
These are the includes:
IFrame.h
#ifndef SRC_POWERSOFT_KSERIES_MESSAGE_IFRAME_H_
#define SRC_POWERSOFT_KSERIES_MESSAGE_IFRAME_H_
#include "../packet/IPacket.h"
namespace amp {
namespace kseries {
namespace message {
namespace frame {
class IFrame {
public:
virtual unsigned int getAddress() const = 0;
virtual ~IFrame();
};
} // frame
} // message
} /* namespace kseries */
} /* namespace amp */
#endif /* SRC_POWERSOFT_KSERIES_MESSAGE_IFRAME_H_ */
ISerializable .h
#ifndef SRC_POWERSOFT_KSERIES_SERDE_ISERIALIZABLE_H_
#define SRC_POWERSOFT_KSERIES_SERDE_ISERIALIZABLE_H_
#include <cstddef>
#include <vector>
namespace amp {
namespace serde {
class ISerializable {
protected:
static std::vector<char> intToChars(int input, int base, int size);
public:
virtual std::size_t serializeTo(char* const buffer, std::size_t buff_size) = 0;
virtual ~ISerializable();
};
} /* namespace serde */
} /* namespace amp */
#endif /* SRC_POWERSOFT_KSERIES_SERDE_ISERIALIZABLE_H_ */
IRequestPacket.h (This one is more for completeness, but I guess it isn't part of the problem
#ifndef SRC_POWERSOFT_KSERIES_MESSAGE_PACKET_IREQUESTPACKET_H_
#define SRC_POWERSOFT_KSERIES_MESSAGE_PACKET_IREQUESTPACKET_H_
#include "IPacket.h"
#include "../payload/IRequestPayload.h"
#include "../../serde/ISerializable.h"
namespace amp {
namespace kseries {
namespace message {
namespace packet {
class IRequestPacket: public IPacket, public serde::ISerializable {
public:
virtual payload::IRequestPayload* getPayload() = 0;
virtual ~IRequestPacket();
};
} /* namespace packet */
} /* namespace message */
} /* namespace kseries */
} /* namespace amp */
#endif /* SRC_POWERSOFT_KSERIES_MESSAGE_PACKET_IREQUESTPACKET_H_ */