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Queue Pointers and values not declared

Tag: c++,compiler-errors,queue,undeclared-identifier

I have been debugging my project for awhile now. All of my files are practically debugged however my Queue.h has issues connecting with them all.

I have a Queue.h file that seems to not process a large sum of my values.

I get issues with my current_queue pointer and other values like initial_rate refusing to be declared. I was hoping anyone could explain why they are not working.

Believe me, this list use to be twice as long.

UPDATE: I fixed the suggested issues with my () and so forth. I am surprised that those corrections corrected everything aside my qurrent_queue and initial_rate values. My errors are lower but those few values seem to hate me :(

ERRORS:

Queue.h:39: error: ISO C++ forbids declaration of ‘ListNode’ with no type
Queue.h:39: error: expected ‘;’ before ‘<’ token
Queue.h: In member function ‘void Queue<NODETYPE>::pop()’:
Queue.h:64: error: ‘current_queue’ was not declared in this scope
Queue.h: In member function ‘void Queue<NODETYPE>::push(const NODETYPE&)’:
Queue.h:70: error: ‘current_queue’ was not declared in this scope
Queue.h: In member function ‘void Queue<NODETYPE>::set_arrivalRate(double)’:
Queue.h:88: error: ‘initial_rate’ was not declared in this scope
Queue.h: In member function ‘int Queue<NODETYPE>::isEmpty() const’:
Queue.h:95: error: ‘current_queue’ was not declared in this scope
Queue.h: In member function ‘int Queue<NODETYPE>::getSize()’:
Queue.h:100: error: ‘current_queue’ was not declared in this scope
Queue.h: In member function ‘void Queue<NODETYPE>::check_new_arrival(int, bool)’:
Queue.h:113: error: ‘initial_rate’ was not declared in this scope
Queue.h:115: error: ‘current_queue’ was not declared in this scope
Queue.h:115: error: missing template arguments before ‘(’ token
Queue.h: In member function ‘int Queue<NODETYPE>::update(int, bool)’:
Queue.h:129: error: ‘current_queue’ was not declared in this scope

Here is my Queue.h file

#ifndef QUEUE_H
#define QUEUE_H
#include <string>
#include <queue>
#include <cstddef>
#include <algorithm>
#include <list>
#include <sstream>
#include "Passenger.h"
#include "Random.h"
#include <iostream>

extern Random simulation_obj;

using namespace std;

template <typename NODETYPE>
class Queue {

public:

Queue(string);
~Queue();
int isEmpty() const;
int getSize();
void check_new_arrival(int, bool);
void set_arrivalRate(double new_rate);
int get_totalWait() const;
int get_servedTotal() const;
void push(const NODETYPE& item);
void pop();
int update(int, bool);
string get_queue() const;
//NODETYPE& front();
//const NODETYPE& front() const;

private:

 ListNode<NODETYPE> *current_queue;
     int count_total;
     int total_wait;
     double initital_rate;
 string QueueName;
};

template <typename NODETYPE>
Queue<NODETYPE> :: Queue(string name) : count_total(0), total_wait(0),
 QueueName(name) {}

template <typename NODETYPE>
void Queue<NODETYPE> :: pop() {

current_queue -> removeFromHead();

}
template <typename NODETYPE>
void Queue<NODETYPE> :: push(const NODETYPE& item){

current_queue -> insertAtHead(item);

}

template <typename NODETYPE>
int Queue<NODETYPE> :: get_servedTotal() const{
    return count_total;
}

template <typename NODETYPE>
int Queue<NODETYPE> :: get_totalWait() const {
    return total_wait;
}

//set arrival
template <typename NODETYPE>
void Queue<NODETYPE> :: set_arrivalRate(double new_rate) {

      initial_rate = new_rate;

}

template <typename NODETYPE>
int Queue<NODETYPE> :: isEmpty(){
            // return true if the queue object is empty
    return current_queue -> isEmpty();
    }//end isEmpty method

template <typename NODETYPE>
int Queue<NODETYPE> :: getSize(){
            return current_queue -> getSize();

    }

template <typename NODETYPE>
string Queue<NODETYPE> :: get_queue() const {
      return QueueName;
}

//See nitial_rate = new_rate;
template <typename NODETYPE>
void Queue<NODETYPE> :: check_new_arrival(int clock, bool display_all){

    if (simulation_obj.next_double < initial_rate) {

            current_queue.push(Passenger(clock));

      if(display_all) {
            cout <<"Time is " << clock << ": " << QueueName
                    << " arrival, new queue size is "
                    << current_queue.getSize() <<endl;
      }

    }
}

template <typename NODETYPE>
int Queue<NODETYPE> :: update(int clock, bool display_all) {

    Passenger<NODETYPE> *next_customer = current_queue.pop();
    //current_queue.pop();

    int time = next_customer.get_initialTime();
    int wait = clock - time;

    total_wait += wait;
    count_total++;

    if(display_all) {

      cout <<"Time is " << clock << ": Serving " << QueueName
      << " with time stamp at " << time << endl;
    }

    return clock + next_customer.get_processTime();
}

#endif

UPDATE:

I will include a few more of my files so that they may be help determining why these two values don't work

Passenger.h

#ifndef PASSENGER_H
#define PASSENGER_H
#include <iostream>
#include "Random.h"

//Use object from Checkout_Simulation.cpp
extern Random simulation_obj;
extern Random item_obj;

template <typename NODETYPE>
class Passenger {

public:


Passenger(int);
int get_initalTime();
int get_processTime();
//  int get_id();
static void set_max_processTime(int max_processTime);

    private:
     //int id;
     int processTime;
     int initalTime;
     static int max_processTimeInterval;
     //sequence for passengers
     //static int id_number;


};

 //Get time Passenger arrived
template <typename NODETYPE>
int Passenger<NODETYPE> :: get_initalTime() {

  return initalTime;

 }
 //Get process time of passenger
template <typename NODETYPE>
int Passenger<NODETYPE> :: get_processTime() {

  return processTime;

}

template <typename NODETYPE>
void Passenger<NODETYPE> :: set_max_processTime(int max_processTime) {

  max_processTimeInterval = max_processTime;

}

// Makes a new customer with their time that they arrived
template <typename NODETYPE>
Passenger<NODETYPE> :: Passenger(int inital){
    //initalTime is from Passenger.h
    initalTime = inital;

    //processTime is from Passenger.h
    processTime = 1 + simulation_obj.next_int(max_processTimeInterval);

}

//Max time to process passenger
template <typename NODETYPE>
int Passenger<NODETYPE> :: max_processTimeInterval;


#endif

Checkout_Simulation.h

#ifndef CHECKOUT_SIMULATION_H
#define CHECKOUT_SIMULATION_H
#include "Queue.h"
#include "Random.h"
#include <iostream>
#include <string>
#include <cctype>

using namespace std;
//Global random generator from Random.h
Random simulation_obj;
Random item_obj;

template <typename NODETYPE>
class Checkout_Simulation{


public:

    int number;
    static int const SIZE = 100;
    int super_items[SIZE];
    int ex1_items[SIZE];
    int ex2_items[SIZE];
    int regular_items[SIZE];

Checkout_Simulation() : super_express("Super Express Counter 01"),
            express_line1("Express Line Counter 01"),
            express_line2("Express Line Counter 02"),
            regular_line("Regular Line Counter 01"), 
            clock_time(0), finish_time(0) {}

void run_sim();
void show_information();
void enter_information();

private:

void start_checkout();
Passenger<NODETYPE> *super_express;
Passenger<NODETYPE> *express_line1;
Passenger<NODETYPE> *express_line2;
Passenger<NODETYPE> *regular_line;

int super_express_max;
int processTime_max;
int total_time;
bool display_all;
int clock_time;
int finish_time;

// number of super_express served since last regular customer
int super_express_since_regular;




};

template <typename NODETYPE>
void Checkout_Simulation<NODETYPE> :: run_sim() {

    for(clock_time = 0; clock_time <total_time; clock_time++){
    item_obj.item_purchase(number);

    if (number < 15) {
      super_express.check_new_arrival(clock_time, display_all);
// number = the value
  super_express.number = number;
}
else if (number >15 && number <=20){

  express_line1.check_new_arrival(clock_time, display_all);
  express_line2.check_new_arrival(clock_time, display_all);
}
else {
  regular_line.check_new_arrival(clock_time, display_all);
    }  



if (clock_time >= finish_time){
            start_checkout();
      }

    }//end for loop
}

template <typename NODETYPE>
void Checkout_Simulation<NODETYPE> :: start_checkout() {

    /* if express lines are both empty and regular, and super_express_since_regular less 
then super_expresses max hold, then update since_regular and super_express     */
    if( (!express_line1.empty() || !express_line2.empty())
            && ( (super_express_since_regular <= super_express_max) ||
            regular_line.empty() )){


            super_express_since_regular++;
            finish_time = super_express.update(clock_time, display_all);

    }//end if

//if the regular line isn't empty, super_express_since_regular = 0 and update regular
    else if (!regular_line.empty()){

            super_express_since_regular = 0;
            finish_time = regular_line.update(clock_time, display_all);

    }//end else if



// if regular_line is not empty and 
//else if (!regular_line.empty() && super_express

else if (display_all){

            cout << "Current time is " << clock_time <<": current counter is empty\n";

    //}// end else if

} 
}

template <typename NODETYPE>
void Checkout_Simulation<NODETYPE> :: show_information(){

    cout << "\n The number of regular customers served was "
            << regular_line.get_servedTotal() << endl;
    double average_wait = double(regular_line.get_totalWait())/
                                    double(regular_line.get_servedTotal());
    cout <<", with average waiting time of " << average_wait << endl;


    cout <<"The number of express customers served in Express Line 01 was "
            << express_line1.get_servedTotal() <<endl;
    average_wait = double(express_line1.get_totalWait())/
                            double(express_line1.get_servedTotal());
    cout <<", with average waiting time of " << average_wait <<endl;


    cout <<"The number of express customers served in Express Line 02 was "
            << express_line2.get_servedTotal() <<endl;
    average_wait = double(express_line2.get_totalWait())/
                            double(express_line2.get_servedTotal());
    cout <<", with average waiting time of " << average_wait <<endl;


    cout <<"The number of super express customers served was "
            << super_express.get_servedTotal() <<endl;
    average_wait = double(super_express.get_totalWait())/
                            double(super_express.get_servedTotal());
    cout <<", with average waiting time of " << average_wait <<endl;


    cout <<"Overall waiting time till all customers are helped is: "<<endl;


    cout <<"Max length of super express line was: "<<endl;

    cout <<"Average free time of super express line was:" <<endl;


}


template <typename NODETYPE>
void Checkout_Simulation<NODETYPE> :: enter_information() {

    double input;
    int max_processTime;
    string response;

    cout <<"Expected number of super_express customers per hour: ";
    cin >> input;
    super_express.set_arrivalRate(input/ 60.0);
    cout <<"Expected number of express customers in Express Line 01 per hour: ";
    cin >> input;
    express_line1.set_arrivalRate(input/60.0);
    cout <<"Expected number of express customers in Express Line 02 per hour: ";
    cin >> input;
    express_line2.set_arrivalRate(input/60.0);
    cout <<"Expected number of regular customers per hour: ";
    cin >> input;
    regular_line.set_arrivalRate(input/60.0);

    cout <<"Enter maximum number of super express customers served between express and regular customers ";
    cin >> max_processTime;
    cout <<"Enter total time in minutes for simulation: ";
    cin >> total_time;
    cout <<"Display simulation at a minute interval (Y or N) ";
    cin >>response;

    display_all = toupper (response[0]) == 'Y';
}

#endif

LinkedList.h

#ifndef LINKEDLIST_H
#define LINKEDLIST_H
#include <iostream>
#include "ListNode.h"

using namespace std;

template <typename NODETYPE>
class LinkedList {

    public:
       LinkedList();
       ~LinkedList();
       int getSize();
       bool isEmpty();
       void insertAtHead(NODETYPE & );
       void insertAtTail(NODETYPE & );

   //Change from bool to NODETYPE
       NODETYPE removeFromHead();
       NODETYPE removeFromTail();

       void printList();
    private:
       int size;
       ListNode<NODETYPE> *firstNode;
       ListNode<NODETYPE> *lastNode;
       ListNode<NODETYPE> *getNewNode(const NODETYPE &);
};

// Now you continue to implementation of LinkedList class using the template<typename NODETYPE> as appropriate in the program, you

//will implement all the public functions, constructor, destructor, and private function. Here is an example of the function getSize()

template<typename NODETYPE>
int LinkedList<NODETYPE>:: getSize() {

    return size;

}

template <typename NODETYPE>
LinkedList<NODETYPE>:: LinkedList()
{

size = 0;
firstNode = NULL;
lastNode = NULL;

}


template <typename NODETYPE>
bool LinkedList<NODETYPE>:: isEmpty()
{
if(firstNode == NULL)
    {
    return true;

    }   
    else
    {
    return false;
    };

}       

template<typename NODETYPE>
void LinkedList<NODETYPE>:: insertAtHead(NODETYPE & newData)
{
ListNode<NODETYPE> *newPtr = getNewNode(newData);

if(isEmpty()) 
{
    firstNode = lastNode = newPtr;
    //  *lastNode = newData;

}
else
{
newPtr -> nextNode = firstNode;
    firstNode = newPtr;
}
size++;
}

template<typename NODETYPE>
void LinkedList<NODETYPE>:: insertAtTail(NODETYPE & newData)
{

ListNode<NODETYPE> *newPtr = getNewNode(newData);

if(isEmpty())
{

 firstNode = lastNode = newPtr;
}
else
{
 lastNode -> nextNode = newPtr;
 lastNode = newPtr;
}

size++;

}


template <typename NODETYPE>
NODETYPE LinkedList<NODETYPE>:: removeFromHead() {

// Edits for Stack

if (!isEmpty()) {
 //makes a temp that is the firstNode
     ListNode<NODETYPE> *tempPtr = firstNode;
    if (firstNode == lastNode){ //or (size == 1)         
         firstNode = lastNode = NULL;
    }
    else {
         firstNode = firstNode -> nextNode;
    }

     NODETYPE tempValue = tempPtr -> getData();
     delete tempPtr;
     size --;
     return tempValue;
}

}

template<typename NODETYPE>
NODETYPE LinkedList<NODETYPE> :: removeFromTail()
 {
if (!isEmpty()){
 ListNode<NODETYPE> *tempPtr = firstNode;

// if only one Node
 if (firstNode == lastNode ) {
    firstNode = lastNode = NULL;
  }
 else{
     //makes a temp that is the firstNode
         //ListNode<NODETYPE> *tempPtr = firstNode;
         while (tempPtr -> nextNode != lastNode){
         tempPtr = tempPtr -> nextNode;
         } //end while

    //makes lastNode the one before the lastnode because temp isn't 
    //suppose to be lastnode due to while loop
         lastNode = tempPtr;
     // makes the temp go to next one which is lastnode
         tempPtr = tempPtr -> nextNode;
     // up to this point temp is lastNode so we cut link and make it null 
     lastNode -> nextNode = NULL;
  }

     NODETYPE tempValue = tempPtr -> getData();
             delete tempPtr;
             size --;
             return tempValue;
 }  
}

/**
Method: printList
This method prints the list content on the screen
*/
template <typename NODETYPE>
void LinkedList<NODETYPE>:: printList()
{
if (isEmpty()) {
 cout <<"The list is empty \n";
}
else {

// prefer while loop due to changing size
ListNode<NODETYPE> *currentPtr = firstNode;
cout <<"The list is: "<<endl;
while (currentPtr != NULL) {

    cout << currentPtr -> data << "\n";
    currentPtr = currentPtr -> nextNode;
}
    cout << endl;
}

}


// Get new Node function
template <typename NODETYPE>
ListNode<NODETYPE> *LinkedList<NODETYPE> :: getNewNode(const NODETYPE & newData) {

return (new ListNode<NODETYPE>(newData));

}


//deconstructor
//delete everything in LinkedList if it is not empty
template <typename NODETYPE>
LinkedList<NODETYPE> :: ~LinkedList() {

if(!isEmpty()){
  cout <<" Deleting all the nodes";
  ListNode<NODETYPE> *currentPtr = firstNode;
  ListNode<NODETYPE> *tempPtr;

  while (currentPtr != NULL) {
    tempPtr = currentPtr;
    currentPtr = currentPtr -> nextNode;
    delete tempPtr;
  }//end while

  cout <<" Release all memory \n";
}

}

#endif

ListNode.h

#ifndef LISTNODE_H
#define LISTNODE_H
#include <cstdlib>

using namespace std;

template<typename NODETYPE> class LinkedList;

template<typename NODETYPE>
class ListNode {

friend class LinkedList<NODETYPE>;

public:

ListNode(const NODETYPE &);
ListNode(const NODETYPE &, ListNode<NODETYPE> *);
    NODETYPE getData();
void setData(NODETYPE &);
ListNode getNextNode() ;
void setNextNode(ListNode <NODETYPE>*);

private:

NODETYPE data;
ListNode<NODETYPE> *nextNode;

};

// Now the implementation of each function in ListNode class. 
//We will be using template NODETYPE through out

template<typename NODETYPE>
ListNode <NODETYPE> :: ListNode(const NODETYPE &newData) 

{

// This is a constructor for ListNode class in which we 
//initialize the nextNode pointer to NULL, and assign data to 
//newData. Please put in your code here

nextNode = NULL;
data = newData;
}


template <typename NODETYPE>
ListNode <NODETYPE>:: ListNode (const NODETYPE &newData, ListNode<NODETYPE> *newNextPtr) {

// This is a constructor for ListNode class in which we 
//initialize the nextNode pointer to newNextPtr, and assign 
//data to newData. Please put in your code here

data = newData;
// now the second variable ptr becomes the next node
nextNode = newNextPtr;
}


template <typename NODETYPE>
NODETYPE ListNode<NODETYPE>::getData() {

// This function returns the value of data
return data;
}


template <typename NODETYPE>
void ListNode <NODETYPE>:: setData( NODETYPE& newData) {

// This function sets data to the value of newData
data = newData;
}


template <typename NODETYPE>
ListNode<NODETYPE> ListNode<NODETYPE>:: getNextNode() {

// This function returns the nextNode pointer
return nextNode;
}



template <typename NODETYPE>
void ListNode<NODETYPE>:: setNextNode(ListNode<NODETYPE> *newNextPtr) {

// This function sets nextNode pointer to newNextPtr
nextNode = newNextPtr;
}

#endif

Random.h

#ifndef RANDOM_H
#define RANDOM_H

#include <cstdlib>
#include <ctime>


class Random {


public:
Random() {

srand((unsigned)time(0));
}

Random(int value) {
srand(value);

}

//Random number for processing time of customer
int next_int(int n) {
 return int(next_double() * n);

}   
//Return random integer range 0 -> 1
double next_double() {

     return double(rand()) / RAND_MAX;
}


int item_purchase(int n) {

//make a case using a number 1-100(100 is max number of items they can have)
n = (rand() % 100) + 1;

return int(next_double() * n);
}

};
#endif

This is my last file which runs everything, however, the main line declaration of the sim_obj won't work. As you can see I have tried three attempts LOL

#include "Checkout_Simulation.h"
#include "Random.h"
#include <iostream>
#include <string>
#include <cctype>
#include "LinkedList.h"

using namespace std;

int main() {

    //Checkout_Simulation sim_obj;
//Checkout_Simulation<int> sim_obj;
Checkout_Simulation<int> *sim_obj = new LinkedList<int>();

    sim_obj.enter_information();
    sim_obj.run_sim();
    sim_obj.show_information();


return 0;
}

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c++

Your error is actually coming from: array.push_back(day); This tries to put a copy of day in the vector, which is not permitted since it is unique. Instead you could write array.push_back( std::move(day) ); however the following would be better, replacing auto day...: array.emplace_back(); ...

Explicit instantiation of class template not instantiating constructor

c++,templates,constructor,explicit-instantiation

When the constructor is a template member function, they are not instantiated unless explicitly used. You would see the code for the constructor if you make it a non-template member function. template<typename T> class test { public: /*** template<typename T> test(T param) { parameter = param; }; ***/ test(T param)...

No match for 'operator*' error

c++,c++11

As @101010 hints at: pay is a string, while hours_day is a float, and while some languages allow you to multiply strings with integers, c++11 (or any other flavor of c) doesn't, much less allow strings and floats to be multiplied together.

Confused about returns in stack template

c++,templates,generic-programming

This depends on what you want the behaviour (protocol) of your class to be. Since you're logging into the error stream there, I assume you consider this an error condition to call pop() on an empty stack. The standard C++ way of signalling errors is to throw an exception. Something...

Translating a character array into a integer string in C++

c++,arrays,string

If you want a sequence of int, then use a vector<int>. Using the key_char string, the values of the chars in it will serve as the initial value of the ints. std::vector<int> key_num(key_char.begin(), key_char.end()); Then, iterate over each character of key_num and convert it to the equivalent int value for...

Make a triangle shape in C++

c++

This code works fine for a right angled triangle - * ** *** But I guess you want a triangle like this - * *** ***** Try this - #include <iostream> using namespace std; int main() { int i, j, k, n; cout << "Please enter number of rows you...

3 X 3 magic square recursively

c++,algorithm,math,recursion

Basically, you are finding all permutations of the array using a recursive permutation algorithm. There are 4 things you need to change: First, start your loop from pos, not 0 Second, swap elements back after recursing (backtracking) Third, only test once you have generated each complete permutation (when pos =...

c++ extend constructor of same class (no inheritance)

c++,constructor

Yes you can as of C++11 standard. Wiki article. Also a quick empirical verification: using namespace std; class A { public: A() { cout << "Hello "; } A(int x) : A() { cout << "World!" << endl; } }; int main() { A a(1); return 0; } Prints: Hello...

opencv window not refreshing at mouse callback

c++,opencv

your code works for me. But you used cv::waitKey(0) which means that the program waits there until you press a keyboard key. So try pressing a key after drawing, or use cv::waitKey(30) instead. If this doesnt help you, please add some std::cout in your callback function to verify it is...

How can I access the members of a subclass from a superclass with a different constructor?

c++,inheritance,constructor,subclass,superclass

This map: typedef map<string, Object> obj_map; only stores Object objects. When you try to put an Image in, it is sliced down and you lose everything in the Image that was not actually part of Object. The behaviour that you seem to be looking for is called polymorphism. To activate...

C++ Isn't this a useless inline declaration?

c++,inline,private,member,protected

The Compiler can Access everything. The restrictions are only valid for the programmer. This means there are no restrictions for the Compiler to Access any variables! At the end every variable is just translated to an address which can be accessed. So for the Compiler it is no Problem to...

pointer to pointer dynamic array in C++

c++,arrays,pointers

The valid range of indices of an array with N elements is [0, N-1]. Thus instead of for example this loop for (int i=1; i <= n; i++) ^^^^ ^^^^^^ you have to write for ( int i = 0; i < n; i++ ) As you used operator new...

Undefined behaviour or may be something with memset

c++,undefined-behavior

The A[32] in the method is actually just a pointer to A. Therefore, sizeof is the size of *int. Take the following test code: void szof(int A[32]) { std::cout << "From method: " << sizeof(A) << "\n"; } int main(int argc, char *argv[]) { int B[32]; std::cout << "From main:...

Test if string represents “yyyy-mm-dd”

c++,command-line-arguments

If you can use boost library you could simple do it like this: string date("2015-11-12"); string format("%Y-%m-%d"); date parsedDate = parser.parse_date(date, format, svp); You can read more about this here. If you want a pure C++ solution you can try using struct tm tm; std::string s("2015-11-123"); if (strptime(s.c_str(), "%Y-%m-%d", &tm))...

MFC visual c++ LNK2019 link error

c++,mfc

The header file provides enough information to let you declare variables. And for that matter to just compile (but not link) code. When you link, the linker has to resolve e.g. function references such as a reference to ServerConnection::getLicenceRefused, by bringing in the relevant machine code. You have to tell...

Marshal struct in struct from c# to c++

c#,c++,marshalling

Change this: [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 36)] private string iu; to this: [MarshalAs(UnmanagedType.LPStr)] private string iu; Note that this code is good only to pass a string in the C#->C++ direction. For the opposite direction (C++->C#) it is more complex, because C# can't easily deallocate C++ allocated memory. Other important thing:...

create vector of objects on the stack ? (c++)

c++,vector,heap-memory

Yes, those objects still exist and you must delete them. Alternatively you could use std::vector<std::unique_ptr<myObject>> instead, so that your objects are deleted automatically. Or you could just not use dynamic allocation as it is more expensive and error-prone. Also note that you are misusing reserve. You either want to use...

dispatch response packet according to packet sequence id

c++,boost,boost-asio

You could use std::promise and std::future (or their boost counterparts if your are not yet on C++11). The idea is to store a std::shared_ptr<std::promise<bool>> with the current sequence id as a key in the map whenever a request is sent. In the blocking send function you wait for the corresponding...

Can python script know the return value of C++ main function in the Android enviroment

python,c++

For your android problem you can use fb-adb which "propagates program exit status instead of always exiting with status 0" (preferred), or use this workaround (hackish... not recommended for production use): def run_exe_return_code(run_cmd): process=subprocess.Popen(run_cmd + '; echo $?',stdout=subprocess.PIPE,shell=True) (output,err)=process.communicate() exit_code = process.wait() print output print err print exit_code return exit_code...

ctypes error AttributeError symbol not found, OS X 10.7.5

python,c++,ctypes

Your first problem is C++ name mangling. If you run nm on your .so file you will get something like this: nm test.so 0000000000000f40 T __Z3funv U _printf U dyld_stub_binder If you mark it as C style when compiled with C++: #ifdef __cplusplus extern "C" char fun() #else char fun(void)...

Strings vs binary for storing variables inside the file format

c++,file,hdf5,dataformat

Speaking as someone who's had to do exactly what you're talking about a number of time, rr got it basically right, but I would change the emphasis a little. For file versioning, text is basically the winner. Since you're using an hdf5 library, I assume both serializing and parsing are...

undefined reference to `vtable for implementation' error

c++,build,makefile

I think you just misspelled CFLAGS in CFLAGES=-c -Wall I'm guessing this is the case since g++ ../src/main.cpp -I ../include/ does not have the -c option...

Parameters to use in a referenced function c++

c++,pointers,reference

Your code makes no sense, why are you passing someStruct twice? For the reference part, you should have something like: void names(someStruct &s) { // <<<< Pass struct once as a reference cout << "First Name: " << "\n"; cin >> s.firstname; cout << "Last Name: " << "\n"; cin...

OpenCV - Detection of moving object C++

c++,opencv

Plenty of solutions are possible. A geometric approach would detect that the one moving blob is too big to be a single passenger car. Still, this may indicate a car with a caravan. That leads us to another question: if you have two blobs moving close together, how do you...

How can I convert an int to a string in C++11 without using to_string or stoi?

c++,string,c++11,gcc

Its not the fastest method but you can do this: #include <string> #include <sstream> #include <iostream> template<typename ValueType> std::string stringulate(ValueType v) { std::ostringstream oss; oss << v; return oss.str(); } int main() { std::cout << ("string value: " + stringulate(5.98)) << '\n'; } ...

Copy text and placeholders, variables to the clipboard

c++,qt,clipboard

You're not using the function setText correctly. The canonical prototype is text(QString & subtype, Mode mode = Clipboard) const from the documentation. What you want to do is assemble your QString ahead of time and then use that to populate the clipboard. QString message = QString("Just a test text. And...

Type function that returns a tuple of chosen types

c++,templates,c++11,metaprogramming

You can do this without recursion by simply expanding the parameter pack directly into a std::tuple: template<My_enum... Enums> struct Tuple { using type = std::tuple<typename Bind_type<Enums>::type...>; }; To answer your question more directly, you can declare a variadic primary template, then write two specializations: for when there are at least...

Incorrect Polar - Cartesian Coordinate Conversions. What does -0 Mean?

c++,polar-coordinates,cartesian-coordinates

You are converting to cartesian the points which are in cartesian already. What you want is: std::cout << "Cartesian Coordinates:" << std::endl; std::cout << to_cartesian(to_polar(a)) << std::endl; std::cout << to_cartesian(to_polar(b)) << std::endl; //... Edit: using atan2 solves the NaN problem, (0, 0) is converted to (0, 0) which is fine....

C++ template template

c++,templates

Your issue is that std::deque (and other standard containers) doesn't just take a single template argument. As well as the stored type, you can specify an allocator functor type to use. If you don't care about these additional arguments, you can just take a variadic template template and be on...

Checking value of deleted object

c++

It is very bad, accessing deleted objects as if they were not deleted will in the general case crash. There is no guarantee that the memory is still mapped inside the process and it could result in a virtual memory page fault. It is also likely that the memory will...

segfault accessing qlist element through an iterator

c++,iterator,qlist

(Edited away first "answer", this is an actual attempt at an answer) My guess: QList<Msg> messages() const { return _messages; } It's returning a copy of the QList _messages, rather than a reference to it. I'm not sure that it would give the results you're seeing, but it looks wrong...

Add more features to stack container

c++,visual-c++,stl

If this is interview question or something , and you have to do it anyways , you can do this like ,below code . derive from std::stack , and overload [] operator #include <iostream> #include <algorithm> #include <stack> #include <exception> #include <stdexcept> template <typename T> class myStack:public std::stack<T> { public:...

Implicit use of initializer_list

c++,c++11,initializer-list

Your program is not ill-formed because <vector> is guaranteed to include <initializer_list> (the same is true for all standard library containers) §23.3.1 [sequences.general] Header <vector> synopsis #include <initializer_list> ... Searching the standard for #include <initializer_list> reveals the header is included along with the following headers <utility> <string> <array> <deque> <forward_list>...

Passing something as this argument discards qualifiers

c++,c++11

There are no operator[] of std::map which is const, you have to use at or find: template<> struct Record::getDispatcher<std::string> { static std::string impl(Record const& rec, std::string& const field) { return rec.fieldValues_.at(field); // throw if field is not in map. } }; or template<> struct Record::getDispatcher<std::string> { static std::string impl(Record const&...

Storing columns on disk and reading rows

c++,file,matrix,io

Mentioned solution with fseek is good. However, it can be very slow for large matrices (as disks don't like random access, especially very far away). To speed up things, you should use blocking. I'll show a basic concept, and can explain it further if you need. First, you split your...