C/C++ :: Unexpected Behavior For Classes That Contain Member Object
Apr 1, 2014
I have a WordRecord that contains a LinkedList (both my doing). I have rigorously tested my LinkedList class, and know that it works (heck, I used it in the last project I had!). The problem is that undefined behaviour seems to happen when using the WordRecord, which has a std::string and a LinkedList<unsigned>. (The problem happens with the LinkedList.)
Here is the code:
main.cpp
#include <iostream>
#include "BinaryTreeNode.h" // here for test purposes
#include "LexicographicTree.h"
#include "LinkedList.h"//also for test purposes
#include "OutputStream.h"
#include "WordRecord.h"
using namespace std;
int main()
{
// setup the OutputStream to print to "test.txt"
OutputStream stream("test.txt");
// create a sampleWordRecord (make it have the word "I" on line 1)
[code]....
One of the requirements for the project is that it must compile on Unix server (I am using Windows, and have tested it in both environments.) I get a core-dump in the Unix environment. On the other hand, the output on-screen in the Windows environment looks right. However, when I open up the text file, I get the following
Sample word record:
WordLines
I{14}
/* I have no what is happening to sampleWordRecord's LinkedList; I am not trying to modify it, except for where I created the sampleWordRecord! */
I have two classes, a Package class and a Person class. The Package class has two Person objects has member variables, a Sender and a Receiver. While overloading the << operator for the Package class so that it will make an output label from everything in the Package class. Here is my code...
class Package{ public: Person Sender; Person Reciever; int weight; double cost; friend ostream &operator<<(ostream &out, Package &pack);
[Code] .....
So my problem is on that last output line, I am unable to call Sender.getName()... etc. Is there a proper syntax so that I can access the members of the Person class while overloading the << operator for the Package class?
I've got two classes, which are both derived from the same two base classes. Here's a representation of the actual code:
Code: #include <vector> class BaseClassA { }; class BaseClassB { }; class TestClassX : public BaseClassA, public BaseClassB
[code].....
Basically, I'd like to know if it is possible to cast directly from a BaseClassA pointer to a BaseClassB pointer, without casting to the child class first.
This refers to an ATL COM DLL project. I can successfully create a class hierarchy of objects, ie. say, one class is the TEAM, which then holds other objects, say, a leader and a secretary, both of which are Employee Classes . Here goes my question:
a) In the Team.h header file I declare m_pLeader as a CComPtr<IEmployee>
Code: classATL_NO_VTABLE CTeam : public CComObjectRootEx<CComSingleThreadModel>, public CComCoClass<CTeam, &CLSID_Team>, public IDispatchImpl<ITeam, &IID_ITeam, &LIBID_BUOBJ05Lib, /*wMajor =*/ 1, /*wMinor =*/ 0> { private: CComPtr<IEmployee> m_pLeader; CComPtr<IEmployee> m_pSecretary;
b) The Employee Class is defined within this ATL COM project. c) In the Team.cpp file, I create an instance in the FinalConstruct code, the focus is on the CEmployee
Code: HRESULT CTeam::FinalConstruct(){ CComObject<CEmployee>* pLeader; HRESULT hr=CComObject<CEmployee>::CreateInstance(&pLeader); if (FAILED(hr)) return hr; m_pLeader=pLeader; // ..same for secretary... return S_OK }
d) Here comes my QUESTION: How must I proceed if the Employee object was part of another ATL COM DLL, that is it would be described in another DLL that I would now like to reuse? I guess I need to
1. Have the other DLL's idl-, tlb, and h file in my project folder. Let me name it "other.h, other.idl, other.tlb"
2. Both h- and cpp-file must have an #include "other.h" statement -- please correct if I am wrong..
3. ...but how must in the Team's h- and cpp-files the statements be (assuming the class in the "other" Dll is Member (instead of Employee? I know the following code will NOT work, so I am asking how it should be correctly?
I am getting a compilation error from the code below. It is when i am naming a variable with my user defined type.
#include<iostream> #include<cstring> #include<cstdlib> using namespace std; class person {
[Code] .....
C:Dev-CppTRIAL.PASS.!!!.cpp In function `int main()': 66 C:Dev-CppTRIAL.PASS.!!!.cpp expected primary-expression before "p" 66 C:Dev-CppTRIAL.PASS.!!!.cpp expected `;' before "p" 74 C:Dev-CppTRIAL.PASS.!!!.cpp `p' undeclared (first use this function) (Each undeclared identifier is reported only once for each function it appears in.) 83 C:Dev-CppTRIAL.PASS.!!!.cpp `X' undeclared (first use this function)
"A nested class has free access to all the static members of the enclosing class. All the instance members can be accessed through an object of the enclosing class type, or a pointer or reference to an object."
How can the members be accessed through an object of the enclosing class type? I understand the pointer and reference part because for them you dont need the full definition, but for creating a object you do?
Also it has free access to all static members because the nested class is part of the enclosed class and with static it exists in everything inside the enclosing class? Right or am I missing something?
I see many time where static data member is used to count creations of objects -
i.e.
1. the static data member is init to 0
2. the static data member is incremented by 1, in the Class' constructor, every time an object is created
However, if you define a global object of a class,
How can you tell that the static data member is initialized BEFORE the constructor of the global object is called? (i.e. before the global object is created).
Because to my understanding, you do not know in advance the order of global objects' creation -
so the Global Object could be created BEFORE the static data member was created and initialized.
This does not allow me to initialize _listRef as something like NULL when it is not applicable.Also, i must change all my constructors and its child class to include an initialization of _listRef!!
What is the alternative? Is pointer the nearest? which of the following should be used?
Code: const QList<QSharedPointer<Data>> * _listRef; or const QList<QSharedPointer<Data>> *const _listRef; or const QSharedPointer<QList<QSharedPointer<Data>>> _listRef; ????
Code: class A { std::map<std::string, Unit*> aMap; class B
[Code] .....
This code snippet results in "A non-static member reference must be made relative to a specific object". When I make callA() static, this error goes away, but there is problem with aMap.
When I create a list control I can assign an image list to it with the ListView_SetImageList().
By default, when just created there is no image list assigned as can be checked with ListView_GetImageList().
Now, what should happen when I do following call:
Create list control. Create an image list Get the current image list Assign an image list to list control Display some items Assign an old image list to list control.
Does strings on the list control should be indented?
There was an "impovement" since Windows 7 in algorithm for selecting the initial directory, which is described here OPENFILENAME structure. Briefly:
Windows 7:
If lpstrInitialDir has the same value as was passed the first time the application used an Open or Save As dialog box, the path most recently selected by the user is used as the initial directory. Otherwise, if lpstrFile contains a path, that path is the initial directory.
Otherwise, if lpstrInitialDir is not NULL, it specifies the initial directory. If lpstrInitialDir is NULL and the current directory contains any files of the specified filter types, the initial directory is the current directory. Otherwise, the initial directory is the personal files directory of the current user. Otherwise, the initial directory is the Desktop folder.
The problem that this behavior is not what users of my program expect. Another constraint is that I need to use old CFileDialog dialog, not Common File Dialogs. I've tried to use advises described on StackOverflow and on MSDN. This solution by EllisMiller works perfectly:
Specifying a full path (including filename) in lpstrFile. The filename of course shows up in the filename box which is annoying. I ended up using a filename of "." and adding a bit of code to clear the filename combobox once the dialog is open.
BUT I can't figure how to clear the filename combobox. I've tried to add hook procedure, enumerate windows and clear text, but this didn't work for me. So, my question is: how can I clear text in the filename combobox of CFileDialog?
I am having trouble compiling my interface. I am trying to store a reference variable as a member variable of the interface object. Compiler says that the variable has not be initiated correctly.
LCD inherits from VisualInterface which is expecting a DisplayDriver object to be passed in (DisplayDriver is another interface, but thats not important).
I pass the displayDriver object in when LCD is instantiated in maininterfaces.zip
I was pasing it before as a pointer but was told that this could cause me problems with memory leaks and a reference was better, but now I cant seem to get it to compile.
I am writing a program which is using SDL library. I have two different classes which one of them is Timer Class and the other is EventHandling Class.
I need to use some member functions and variables of Timer in some Eventhandling Class member functions, Although I want to define an object of Timer in int main {} and relate it to its member function that has been used in Eventhandling member function in order that it becomes easier to handle it, I mean that I want to have for example two objects of timer and two objects of Eventhandling class for two different users.
I do not know how to relate an object of a class from int main{} to its member function which is being used in another class member function.
I am currently trying to understand why this example for using an array as an argument in a function has a different result than what the lecture notes say it should be.
So supposedly sum should return with the value 28, but I get 27 no matter what. I also am not very good at reading and understanding what exactly the order of operations for this function are.
Code: #include <iostream> using namespace std;
int sum(const int array[], const int length) { long sum = 0; for (int i = 0; i < length; sum += array[++i]); return sum;
I am working through Binary IO with objects and am running into a curious error.
The program executes perfectly until it hits the very end. At "return 0", the program fails. The debugger picks up SIGABRT when executing "return 0". This seems to me to indicate a deconstructor problem of some kind. However, I can't seem to find any deconstructor problems (I am fairly new at programming though).
then the program finishes exiting without error . . . . but the whole point is to be able to read from the binary file. With those two lines in the code, the program successfully reads from the file and outputs the objects to the console ,but fails at "return 0";
Here is the code:
#include <iostream> #include <fstream> #include "Student.h" using namespace std;
I have an array of (Student)classes created in Manager.h, which contains a new instance of class Name (name),(in Student.h)How would I go about accessing the SetFirstName method in Name.cpp if I was in a class Manager.cpp? I have tried using Students[i].name.SetFirstName("name");
// In Manager.h #include"Student.h" class Manager {
I'm getting unexpected output in 2 different cases. The 1st deals with bitfields. The C++ standard has this line about integral promotions:
An rvalue for an integral bit-field (9.6) can be converted to an rvalue of type int if int can represent all the values of the bit-field; otherwise, it can be converted to unsigned int if unsigned int can represent all the values of the bit-field.
If the bit-field is larger yet, no integral promotion applies to it. If the bit-field has an enumerated type, it is treated as any other value of that type for promotion purposes.
This sounds like the value of a bitfield will always be treated as a signed int if the signed representation of the value will fit in the bits. This seems to hold true for my C compiler, but not my C++ compiler.
I tried storing a small negative value in a bitfield that has enough bits to store the sign bit and the value. But when I print out the bitfield, I always get a large number
The other issue I'm having is sort of similar. I'm trying to store 4294967295 into a float, but when I print it out, I get 4294967296. i've tried storing a few other large values like this and what's printed out is rarely the value I stored. I thought it might be because of some int to float conversion, so I tried 4294967295.0. Still no luck. Then I remember that defaults to a double so maybe that's the issue so I tried 4294967295.0f. Still no luck. Why can't I store the correct value here? I don't think it's an IEE format thing since I can use these values as floats on a calculator program.
The example code showing both issues is below.
Code: #include <stdio.h> typedef struct { signed char x : 5; signed char y : 3; }my_struct_t;
My compiler (GCC) keeps expecting an expression where it shouldn't in 1 specific piece of my code:
int zxcNewWindow( HWND parent, TCHAR *text, zxWINDOW *kid, UINT style, int x, int y, int w, int h, int type ) // right here { *kid = zxDefWINDOW;
The project contains only 2 files right now and the settings are just the default for an empty Code::Blocks 12.11 project. Both files are in UTF-8 format (tried in ASCII too), I just cannot see why this is not compiling correctly. I'll post the files in the next two posts.
Edit: For those of you who didn't get what the error was from the above here's the full log:
mingw32-gcc.exe -Wall -g -DzxDEBUG -c C:MePrjscppzxGUImain.c -o objmain.o C:MePrjscppzxGUImain.c: In function 'zxcNewWindow': C:MePrjscppzxGUImain.c:39:10: error: expected expression before '{' token Process terminated with status 1 (0 minutes, 0 seconds) 1 errors, 0 warnings (0 minutes, 0 seconds)
