I've been trying to figure out how to get a return value back from a thread, and found all kinds of info on promises, futures, packaged_somethings, async, ....
Here's one of my failed attempts at promises/futures: [URL] ....
I've just started coding a "Mathematics" library for my own, just to practice some OOP concepts, but sadly I didn't get too far with it before the first errors appeared. That is, I created a Matrix.H and Matrix.CPP file (separate class) in a "Linear Algebra" folder.
However, when I run the code I get the following (linker?) error:
#include <iostream>
#include "Matrix.h"
using namespace std;
int main() {
Matrix<int> A(7,5);
int row[] = {5, 10, 9, 11, -5};
[Code] ....
I am using Visual Studio 2012 (stating this in case it could be related to the reason for which I get the error).
I am trying to write a program that will take a list of integers from a file and write them to another text file. I've been banging my head at this for days trying to get it to compile as it is riddled with linker and compiler errors.
**************************header*************************
#ifndef LINKEDLIST_H
#define LINKEDLIST_H
#include <iostream>
using namespace std;
template <class T>
class linkedList {
[Code] ....
In windows thread function not a void (as pthread in Linux).
Its type is DWORD(unsigned int) so my question is
How to return a struct (contain alot of different data types) from DWORD (unsigned int) thread in windows?
Code:
#include <windows.h>
#include <stdio.h>
#include <conio.h>
typedef struct {
char* name;
int id;
[Code] .......
I am writing a program in C. The following is an extract from my code:
Code:
enum coin_types{
FIVE_CENTS=5,
TEN_CENTS=10,
TWENTY_CENTS=20,
FIFTY_CENTS=50,
ONE_DOLLAR=100,
TWO_DOLLARS=200
[Code] .....
I'm getting the following errors:
For: new = new_coins_data_line(line);
"Incompatible types in assignment"
For: return newdata;
"Incompatible types in return"
There seem to be problems with my variables and perhaps it is related to the type 'struct coin' which has an enumerated type within it.
I have a class which I wrote and one of its object is "SerialPort" .NET class. In my MainWindow I created instance of my class called "SerialPortComm", then I send through some functions of mine, commands to the Serial Port, and I receive answers through "DataReceived" event.
But when I trying to use Dispatcher.BeginInvoke to write my data I have received (successfully), nothing shows on the RichTextBox which I'm trying to write to.
What can caused that, and How I can make it works?
SerialPortComm.cs
public partial class SerialPortComm : UserControl {
public SerialPort mySerialPort = new SerialPort();
public void Open_Port(string comNumber, int baudRate) {
mySerialPort.PortName = comNumber;
mySerialPort.BaudRate = baudRate;
[Code] ....
I wrote a routine in one C++ file and I decided to break it up into some smaller more manageable C++ files. When I copied the variables out of the first one and into the new smaller file (same solution), everything compiles fine but I get a ton of linker errors saying the variables have already been defined in another (the previous) file. Using Visual Studio 2008.
View 5 Replies View RelatedI am getting undefined references when compiling a project, however, there in no reference to external library and I am including all source file and header in the project , beside the only reference is to standard C header files. The undefined references error I am getting is for a header file whose source file is already present in the project.
View 6 Replies View RelatedI was working on template and found the linker error while compiling the code.
Below is the code:
Code: //Template1.h: Header file where template define
#ifndef __Template1_H__
#define __Template1__
template <typename T,typename T1> class A
{
T a;
T1 b;
public:
A(T ,T1 ) ;
[code].....
how to remove the linker error as mentioned above..
i have created a simple program in C++ as given below
#include<iostream.h>
#include<conio.h>
void add(int a,int b);
[Code]....
i saved it with name PIYUSHAN.cpp.after compiling above program, it shows no errors, that means it get compiled successfully. but when I try to run this program it shows Linker error :
Undefined symbol add(int,int) in module PIYUSHAN.CPP
Linker error : Undefined symbol sub(int,int) in module PIYUSHAN.CPP
Linker error : Undefined symbol mul(int,int) in module PIYUSHAN.CPP
Linker error : Undefined symbol div(int,int) in module PIYUSHAN.CPP
If I DEFINE a global variable in two source files which belong to the same project, then there is a linker error "multiply defined symbols". But if I DEFINE a global variable in two source files which belong to the different projects, then it compiles fine. Why?
View 8 Replies View RelatedI have this code in my project
Code:
// OpenGL1.cpp : main project file.
// #include "stdafx.h"
#include "windows.h"
#include <GL/gl.h>
[Code] ....
and I got this error:
Configuration: Debug Win32 ------
1> OpenGL1.cpp
1>LINK : fatal error LNK1104: cannot open file 'C:Program FilesMicrosoft SDKsWindowsv7.0AIncludegl.obj'
Why it wants the gl.obj and how to make this code working without error?
Code:
/** Add a feature to a (mutable) LV2 feature array. */
static inline void
suil_add_feature(LV2_Feature*** features,
unsigned* n,
const char* uri,
void* data) {
for (unsigned i = 0; i < *n && (*features)[i]; ++i) {
if (!strcmp((*features)[i]->URI, uri)) {
[Code] ....
suil_add_feature is used to add features to an existing array of pointers to type LV2_Feature. Initially, the array gets searched to see if the feature already exists. If it doesn't, the existing array gets increased by one element which then gets initialized to the new LV2_Feature value. Resizing is done using realloc()
I'm having a problem when I build a Debug version. The first 5 times I call suil_add_feature() realloc() ends up calling _realloc_dbg() (in dbgheap.c) and everything works fine. But on the sixth call, realloc() calls _realloc_base() (in realloc.c) which brings everything crashing down. I assume that _realloc_base() is intended for the normal (non-debug heap). So this particular app is somehow linking to both the debug and non-debug runtime modules.
If I was building using the VS IDE I could probably figure this out - but although my compiler is MSVC, my build environment is waf, which I'm a bit unfamiliar with. I'm guessing I need to add some lines to my waf script to let it know that it shuld ignore the non-debug runtime libraries when building a Debug version.
Can I achieve this by adding /NODEFAULTLIB to the linker options or is it more complicated than that?
I have a project that is essentially a hot pot of C/asm (naked functions etc). The code gets injected into another EXE. It works fine when compiled in Visual C++ 6 but when compiled in Visual Studio 2008 it compiles fine but falls over in use.
Are there certain settings I need to look out for? I have optimization disabled and as far as I can tell the command line options for compiler/linker are the same (given the differences).
I have opened both builds in IDA and the 2008 build has more import and offset jumps are in different places.
We have a midi.cpp which includes midi_synth.h.
this h file declares a class and this class inlines a open method.
Now the linker doesn't recognize this open method when called by another method inside midi.cpp.
What would I do?
#include <graphics.h>
#include <stdio.h>
#include <conio.h>
#include <math.h>
void main() {
int gd = DETECT, gm = DETECT, s, dx, dy, m, x1, y1, x2, y2;
float xi, yi, x, y;
[Code] ....
I'm writing some functions pertaining to binary trees. I've used recursion once before while learning quicksort but am still quite new and unfamiliar with it. And this is my first time touching a binary tree. So my question: In my addnode function, will the return root statement at the end ever return a value other than the value passed to the function?
Code:
#include <stdlib.h>
struct tnode
{
int data;
struct tnode * left;
struct tnode * right;
}
[code]....
From the page: [URL] ....
#include <iostream>
using namespace std;
int n;
int& test();
[Code] ....
Explanation
In program above, the return type of function test() is int&. Hence this function returns by reference. The return statement is return n; but unlike return by value. This statement doesn't return value of n, instead it returns variable n itself.
Then the variable n is assigned to the left side of code test() = 5; and value of n is displayed.
I don't quite understand the bold sentence. Shouldn't value of n and variable n be the same?
Linker error.
First off the error
Code:
Error1error LNK2019: unresolved external symbol "public: __thiscall ReachTop<class Character>::ReachTop<class Character>(class Character *)" (??0?$ReachTop@VCharacter@@@@QAE@PAVCharacter@@@Z) referenced in function "void __cdecl `dynamic initializer for 'gReachTop''(void)" (??__EgReachTop@@YAXXZ)Main.objDecisionTest
Reach Top class inherits from Goal Class
Goal Class
Code:
#ifndef _GOAL_H
#define _GOAL_H
#include "Action.h"
#include <list>
template <class T>
class Goal
[Code] ....
Code to create
Code:
Character* gCharacter = new Character(1, gWorld);
Goal<Character>* gReachTop = new ReachTop<Character>(gCharacter);
I can provide the character class and its inheritance aswell if you like.
I have a function in one src file called from code in a different src file.
In ig_cfunc.cpp
Code:
#include "ig_tools.h"
int x2_count = 0.0;
float rel_branch_degree_tmp = 0.0;
string type;
vector<int> is_disp_type;
[Code] ....
I am getting a linker error,
Code:
ig_cfunc.cpp:1609: error: `calc_rel_branch_degree' undeclared (first use this function)
I have deleted all of the objects and recompiled to make sure that everything is in sync. I can't see what the issue is here and I'm not sure what to do next. This code actually worked until I changed the name of the function, so the types are all correct and such. This is the format I use for all external functions ....
I have the following code below. I am getting a memory access violation when accessing cmd->query_string in the loop function. The loop() function is running in another thread. The cmd object appears to be destroyed after calling the send_command function. How do I create an object on the heap and access the query_string.
std::list<my_command_message_que*> my_command_que;
void loop(){
if(my_command_que.size() > 0){
my_command_message_que * cmd = my_command_que.front();
std::cout << cmd->query_string;
[Code] ....
I've been using threading for a while, that was no needing parameters. so I used for example the following line :
_beginthread(functionName, 0, (void*)10);
and it worked great...
but now I have a function that has an int parameter (int num), and I dont know how to transfer it using _beginthread...
I was working on a problem that was best solved with chaining threads together using a blocking thread-safe queue. Eg threads A and B pass data to each other using a queue ... a simple producer consumer design A -> B. This has two benefits: 1) being that there is a buffer between the two threads to cache for a slow consumer and 2) allows for better throughput when loads of data are high because the two can run in parallel. Most of the time the design works well under load. but I found when pushing data through the threads intermittently, i.e. once about 0.5 seconds it ran poorly, mostly from what seemed to be latency introduced during the OS waking up of the consumer thread B.
What i have come up with to solve this issue is what i call an .... Its a wrapper around a basic thread safe queue and adds one extra function called .... The idea here is that if you have a simple case (or perhaps a slightly more complicated case) of two threads in a prod cons design and you know the producer will create or received the data, process it, and then push onto the queue, why not give the consumer thread a heads up to let it know the data is about to arrive. In this case call .... In this way you can have the consumer thread in a polling state anticipating the arrival of data and avoid the time to schedule it back to a running state.
Anyway, i have some code below and I was looking to get some feedback. I have tested it somewhat and it does improve the responsiveness quite substantially.
I don't know if I've setup the thread correctly or not, but its behavoir isn't what I'd expect. I'm creating the thread within a BN_CLICKED message
typedef struct my_TNFO {
HANDLE h_event;
HANDLE h_thread;
DWORD thread_id;
BOOL running;
BOOL init;
BOOL canceled;
[Code] ....
progd->count was devised to stop the thread when the recursion ended by posting a message to the main window. When it reaches 1, the def procedure sends the WMU_DISC_DONE message to set the event
All that *appears* to work; however, if I cancel the recursion thread, the list view continues to populate for a bit and then deletels all but 1 item though I send the message LVM_DELETEALLITEMS.
If I move the (tmp->canceled == TRUE) test inside of the do-while, the app gets loopy.
Startthread get called to launch to update list box.
a)is it the only way to pass string to the PostMessage?. my concern is that allocate using new in each iteration each time slows it down a bit.
b)does OnAddToListBox look memory leak free?.
c)What is the best way handle m_pThread at the end?. Any way to improve it?.
Code:
UINT CMyDlg::Dump(LPVOID lparam) {
HWND *pHndl = static_cast<HWND *>(lparam);
char buffer[200];
for (int i = 0; i < 100; i++) {
sprintf_s(buf,"user %d, data %s",i, "Connected");
[Code] ....
I use MFC Find console window and send key to console like this.
Code:
HWND w;
w = FindWindow(NULL, L"c:userspkrudocumentsvisual studio 2010ProjectsCleanVirusDebugCleanVirus.exe");
[Code]....
After program process success in console it not close console windows but it show like this in Output
The thread 'Win32 Thread' (0x1300) has exited with code 0 (0x0).
I think if I can check when VC will show this line, then I can use FreeConsole(); for close console windows.