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  • How to pass a member function to a function used in another member function?

    - by Tommaso Ferrari
    I found something about my problem, but I don't already understand very well. I need to do something like this: class T{ double a; public: double b; void setT(double par){ a=par; }; double funct(double par1) { return par1/a; } void exec(){ b=extfunct(funct, 10); } } double extfunct(double (*f)(double),double par2){ return f(par2)+5; } Operation and function are only for example, but the structure is that. The reason of this structure is that I have a precostituited class which finds the minimum of a gived function (it's extfunct in the example). So I have to use it on a function member of a class. I understood the difference between pointer to function and pointer to member function, but I don't understand how to write it. Thanks, and sorry for the poor explanation of the problem.

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  • What is wrong with my version of strchr?

    - by Eduard Saakashvili
    My assignment is to write my own version of strchr, yet it doesn't seem to work. Any advice would be much appreciated. Here it is: char *strchr (const char *s, int c) //we are looking for c on the string s { int dog; //This is the index on the string, initialized as 0 dog = 0; int point; //this is the pointer to the location given by the index point = &s[dog]; while ((s[dog] != c) && (s[dog] != '\0')) { //it keeps adding to dog until it stumbles upon either c or '\0' dog++; } if (s[dog]==c) { return point; //at this point, if this value is equal to c it returns the pointer to that location } else { return NULL; //if not, this means that c is not on the string } }

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  • Need recommendation for object serialization library in c++

    - by michael
    Hi, I am looking for recommendation for object serialization/deserialization library in c++? Which one are the most advanced and open-sourced? Can it handle Any class that users defined? Object hierarchy (parent and child classes)? A Tree of objects? Class A has an attribute of Class B which has an attribute of Class C? STL containers? Class A has a vector of Class B? A cyclic of objects? Class A has a pointer pointing to B which has a pointer to A? I find boost serialization library. I am not sure what is its limitation from http://www.boost.org/doc/libs/1_42_0/libs/serialization/doc/tutorial.html

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  • C++ String pointers

    - by gnm
    In my previous app I had an object like this: class myType { public: int a; string b; } It had a lot of instances scattered everywhere and passed around to nearly every function. The app was slow. Profiling said that 95% of time is eaten by the string allocator function. I know how to work with the object above, but not how to work with string pointers. class myType { public: int a; string* b; } They told me to use pointers as above. How much faster is it with a string pointer? What is copied when I copy the object? How to the following using the class with the pointer: Access the string value Modify the string value without modifying the one in the object (copy?) General things that change if I use string pointers?

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  • Proper way to handle issue when porting 32 to 64 bit. Conversion from DT1 to DT2 of greater size

    - by grobartn
    So I am trying to port 32 bit to 64 bit. I have turned on the VS2008 flag for detecting problems with 64 bit. I am trying following: char * pList = (char *)uiTmp); warning C4312: 'type cast' : conversion from 'unsigned int' to 'char *' of greater size Disregard the code itself. This is also true for any pointer, because 64 bit pointer is greater than 32 bit unsigned int or int for that purpose. Given that you have to cast smaller type to greater how would you go about doing it so it correctly on both 32/64 bit systems

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  • read successive frames OpenCV using cvQueryframe

    - by AtharvaI
    Hi all I have a basic question in regards to cvQueryFrame() in OpenCV. I have the following code: IplImage *frame1,*frame2; frame1 = cvQueryFrame(capture); frame2 = cvQueryFrame(capture); Now my question is: if frame1 is a pointer to the first frame, is frame2 a pointer to the 2nd frame? So will the two cvQueryFrame() calls read successive frames? I thought I'd check myself first but the pointers frame1,frame2 seem to have the same hex value. :s I just need to capture two frames at a time and then need to process them. Thanks in advance

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  • What is the result of "new int[ 0 ]"? [closed]

    - by ArunSaha
    Possible Duplicates: What does zero-sized array allocation do/mean? C++ new int[0] — will it allocate memory? int * p; p = new int[ 0 ]; What is the expected outcome when new is called for zero number of elements? Is the outcome defined or undefined? Further, is it okay to call delete [] p; on that pointer? What is the intuition/analogy to this situation of pointer to an array of zero elements? Thanks in advance. Regards, Arun

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  • PHP , What is the difference between fopen r+ and r ! does it matter if i used r+ when not intending

    - by Naughty.Coder
    when I use fopen function , why don't I use r+ always , even when I'm not going to write any thing ... is there a reason for separating writing/reading process from only reading .. like , the file is locked for reading when I use r+ , because i might write new data into it or something ... another question : in php manual a+ : Open for reading and writing; place the file pointer at the end of the file. If the file does not exist, attempt to create it. What is supposed to be read if you are at the end of the file ..(pointer at the end) !!? where to learn more about the filesystem thing .... it's confusing

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  • C++ Memory allocation question involving vectors

    - by TheFuzz
    vector< int > vect; int *int_ptr = new int(10); vect.push_back( *int_ptr ); I under stand that every "new" needs to be followed by a "delete" at some point but does the clear() method clean this memory? What about this method of doing the same thing: vector< int > vect; int int_var = 10; vect.push_back( int_var ); From what I understand, clear() calls the variables destructors, but both vect.push_back() methods in this example push an object on the vector, not a pointer. so does the first example using an int pointer need something other than clear() to clean up memory?

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  • How is push()ing and pop()ping defined?

    - by Helper Method
    I know how the push() and pop() methods in a typical implementation of a Queue/Linked List work but what I do want to know is what you actually define as a push or a pop? When can you name a method push()/pop()? What makes the insert()/add() method in a typical Tree implementation not a push()? My understanding is that push()ing means putting something to a position some special pointer is pointing to, and pop()ping an element means putting some object away some pointer is pointing to, but it doesn't seem to be clearly defined. Or does the naming matter at all?

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  • Record Name field in DNS responce

    - by Lescott
    I just read about DNS protocol, and found, that the name field can be writen in two ways: lenght of the next label the label lenght of the next label the label ... zero-byte pointer to the previous name field Next is the original article fragment: The Resource Record Name field is encoded in the same way as the Question Name field unless the name is already present elsewhere in the DNS message, in which case a 2-byte field is used in place of a length-value encoded name and acts as a pointer to the name that is already present. So, my question is, how can I determine the first or the second way is using in a package?

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  • C++: Throwing shared_ptr of derived and catching shared_ptr of base?

    - by hasvn
    Ok, I've been told this problem: Why can you throw a pointer to a derived class and catch a pointer to its base... but you can't do that with shared_ptrs? Example, this works: class Base {}; class Derived : public Base {}; int main() { try { throw new Derived() ; } catch( const Base2 * b ) { printf("Received a base" ) ; } return 0 ; } But this doesn't int main() { try { throw std::tr1::shared_ptr<Derived>( new Derived() ) ; } catch( const std::tr1::shared_ptr<Base> & b ) { printf("Received a base" ) ; } return 0 ; } Any ideas?

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  • C# equivalent of recv?

    - by mlh
    Hello, I have a portion of C code that I am trying to port over to C#. In my C code, I create a socket and then issue a receive command. The receive command is void receive(mysocket, char * command_buffer) { recv(mysocket, command_buffer, COMMAND_BUFFER_SIZE, 0); } now, the command buffer is returned with new values including command_buffer[8] being a pointer to a string. I'm really confused as to how to do this in C# because C# Read() command specifically takes in bytes and not char. The important part is that I get the pointer to the string. Any ideas?

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  • typedef to store pointers in C

    - by seriouslion
    The Size of pointer depends on the arch of the machine. So sizeof(int*)=sizeof(int) or sizeof(int*)=sizeof(long int) I want to have a custom data type which is either int or long int depending on the size of pointer. I tried to use macro #if, but the condition for macros does not allow sizeof operator. Also when using if-else, typedef is limited to the scope of if. if((sizeof(int)==sizeof(int *)){ typedef int ptrtype; } else{ typedef long int ptrtype; } //ptrtype not avialble here Is there any way to define ptrtype globally?

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  • Visual C++ CreateThread Parameter Problem

    - by Vanwaril
    I have a class that contains a function that calls create thread, and needs to pass itself (this) as a parameter: DWORD threadId; HANDLE h = CreateThread( NULL, 0, runThread, this, 0, &threadId); My runThread definition is as follows: DWORD WINAPI runThread(LPVOID args) { Obj *t = (Obj*)args; t->funct(); return 0; } Unfortunately, the object t that I get in runThread() gets garbage. My Obj class has a function pointer attribute. Could that be the problem? class Obj{ void(*funct)(); and in the constructor: Obj(void(*f)()) { funct = f; } where is my mistake? The function pointer, the createThread itself, or type-casting? I tried whatever I could think of.

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  • How to efficiently render different things at different times in a game?

    - by Baqjohanson
    Sorry for the ambiguous title. What I am wondering is what is an efficient way to alternate rendering between lets say a main menu, options menu, and "in the game." The only two ways I've come up with so far are to have 1 render function, with code for each part (menu, ...) and a variable to control what gets drawn, or to have multiple render functions, and use a function pointer to point to the appropriate one, and then just call the function pointer. I always wonder how more professional games do it.

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  • Pointers and collection of pointers in C++. How to properly delete.

    - by Julen
    Hello, This is a newbe question but I have alwasy doubts with pointers in C++. This is the situation. I have a class A which as a collection (a vector actually) of pointers of class B. This same class A has another collection of pointers to class C. Finally the objects of class B have also a collection to pointers to class C which point to the same instances the class A points to. My question is, if I delete a member of class-C-type pointer in class B, what happens to the pointer in class A that points to the deleted instance of class C? How this situation has to be treated? Thanks a lot in advance! Julen.

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  • Boost MultiIndex - objects or pointers (and how to use them?)?

    - by Sarah
    I'm programming an agent-based simulation and have decided that Boost's MultiIndex is probably the most efficient container for my agents. I'm not a professional programmer, and my background is very spotty. I've two questions: Is it better to have the container contain the agents (of class Host) themselves, or is it more efficient for the container to hold Host *? Hosts will sometimes be deleted from memory (that's my plan, anyway... need to read up on new and delete). Hosts' private variables will get updated occasionally, which I hope to do through the modify function in MultiIndex. There will be no other copies of Hosts in the simulation, i.e., they will not be used in any other containers. If I use pointers to Hosts, how do I set up the key extraction properly? My code below doesn't compile. // main.cpp - ATTEMPTED POINTER VERSION ... #include <boost/multi_index_container.hpp> #include <boost/multi_index/hashed_index.hpp> #include <boost/multi_index/member.hpp> #include <boost/multi_index/ordered_index.hpp> #include <boost/multi_index/mem_fun.hpp> #include <boost/tokenizer.hpp> typedef multi_index_container< Host *, indexed_by< // hash by Host::id hashed_unique< BOOST_MULTI_INDEX_MEM_FUN(Host,int,Host::getID) > // arg errors here > // end indexed_by > HostContainer; ... int main() { ... HostContainer testHosts; Host * newHostPtr; newHostPtr = new Host( t, DOB, idCtr, 0, currentEvents ); testHosts.insert( newHostPtr ); ... } I can't find a precisely analogous example in the Boost documentation, and my knowledge of C++ syntax is still very weak. The code does appear to work when I replace all the pointer references with the class objects themselves. As best I can read it, the Boost documentation (see summary table at bottom) implies I should be able to use member functions with pointer elements.

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  • Windows Server Backup fails to backup Hyper-V VM with "Access is denied"

    - by Sebastian Krysmanski
    I'm trying to use Windows Server Backup on my Windows Server 2012 box to backup my Hyper-V VMs. I created a backup job but each job ends with some "Access is denied" errors. One of my VMs (Linux Server) is backed up properly. All others (one Windows 8, one Linux) are not (or at least it seems that way from the looks of the log file below). How can I solve this problem? Here's the log I'm getting: Error in backup of D:\ during read: Error [0x80070005] Access is denied. Application backup Writer Id: {66841CD4-6DED-4F4B-8F17-FD23F8DDC3DE} Component: C435964E-C07A-4958-BA73-A04C6583280F Caption : Backup Using Saved State\Alter Server Logical Path: Error : 8078010E Error Message : Copy of the files failed. Detailed Error : 80070005 Detailed Error Message : (null) Writer Id: {66841CD4-6DED-4F4B-8F17-FD23F8DDC3DE} Component: E780F138-9676-42FB-821C-4561B9B263DC Caption : Backup Using Child Partition Snapshot\Windows 8 Logical Path: Error : 8078010E Error Message : Copy of the files failed. Detailed Error : 80070005 Detailed Error Message : (null) Writer Id: {66841CD4-6DED-4F4B-8F17-FD23F8DDC3DE} Component: Host Component Caption : Host Component Logical Path: Error : 8078010E Error Message : Copy of the files failed. Detailed Error : 80070005 Detailed Error Message : (null)

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  • How to install PHP5.3 and SQLite3 on Ubuntu 8.04

    - by richard
    Hello, I got a Ubuntu Hardy VPS and I am trying to install PHP5.3 with SQLite. I added the dotdeb PHP5.3 repository and succeeded in installing PHP5.3. But I need to install SQLite as well. When I'm trying to install php5-sqlite3 (sudo aptitude install php5-sqlite3) this is the output: The following packages are BROKEN: php5-sqlite3 The following NEW packages will be automatically installed: php-db php-pear php-sqlite3 The following NEW packages will be installed: php-db php-pear php-sqlite3 0 packages upgraded, 4 newly installed, 0 to remove and 0 not upgraded. Need to get 460kB of archives. After unpacking 3027kB will be used. The following packages have unmet dependencies: php5-sqlite3: Depends: phpapi-20060613 which is a virtual package. Resolving dependencies... The following actions will resolve these dependencies: Remove the following packages: libapache2-mod-php5 php5 php5-mysql Install the following packages: php-pear [5.2.4-2ubuntu5.10 (hardy-updates, hardy-security)] Downgrade the following packages: php5-cli [5.3.1-0.dotdeb.1 (<NULL>, now) -> 5.2.4-2ubuntu5.10 (hardy-updates, hardy-security)] php5-common [5.3.1-0.dotdeb.1 (<NULL>, now) -> 5.2.4-2ubuntu5.10 (hardy-updates, hardy-security)] php5-suhosin [5.3.1-0.dotdeb.1 (<NULL>, now) -> 0.9.22-1 (hardy)] Score is 197 Accept this solution? [Y/n/q/?] Obviously, downgrading PHP is not an option. Please help me! If upgrading the server to a newer release of Ubuntu makes things easier, that's not a problem.

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  • VSS Post Backup failures for Virtual Server 2005 R2 SP1 virtual machines

    - by califguy4christ
    We've been seeing strange errors with Volume Shadow Copy services on our Virtual Server 2005 R2 SP1 host. It appears to be failing on a strange mountpoint in the C:\WINDOWS\Temp\ folders, which I believe is used by VSS to mount a writeable image file. To summarize: The Microsoft Virtual Server 2005 Writer continually goes into a failed retryable state The Virtual Server log reports errors during the Post Backup phase VSS reports errors backing up a mount point of unknown origins The mount point causes NTFS and ftdisk errors The host is x86 Windows Server 2003 Standard, SP2. The virtual machine is the same. Both use basic disks. Here is the writer state: Writer name: 'Microsoft Virtual Server 2005 Writer' Writer Id: {76afb926-87ad-4a20-a50f-cdc69412ddfc} Writer Instance Id: {78df98e2-bf19-4804-890b-15865efef3bd} State: [11] Failed Last error: Retryable error From the Virtual Server log: Virtual Server - Vss Writer - Event ID: 1035: The VSS writer for Virtual Server failed during the PostBackup phase. The guest shadow copies did not get exposed on the host machine, after mounting all the virtual hard disks of the virtual machine VMACHINE. From the Application log: VSS - None - Event ID: 12290: Volume Shadow Copy Service warning: GetVolumeInformationW( \\?\Volume{fb84bae7-87f5-11dd-9832-001cc4961ca6}\,NULL,0, NULL,NULL,[0x00000000], , 260) == 0x0000045d. hr = 0x00000000. From the System log: Ntfs - Disk - Event ID: 55: The file system structure on the disk is corrupt and unusable. Please run the chkdsk utility on the volume C:\WINDOWS\Temp\ {fb84bae7-87f5-11dd-9832-001cc49.... My current theory is that VSS creates a mount point for an image file of the VHD, then the software panics for some reason, leaving everything in an inconsistent state. Removing the mount point doesn't resolve the problem. All of the other disks check out fine with CHKDSK. There's no exclusion option for VHDs or to turn off online backups. Has anyone seen this kind of thing before or point me in the right direction for getting more information about the mount point and it's origins? I haven't been able to trace what application is creating that mount point.

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  • So Close: How to get this SSH login working (.bashrc)

    - by This_Is_Fun
    Objective: SSH login ( + eliminate warning message) / run 2 commands / stay logged in: EDIT: Oops, I made a mistake (see below): This code does ~95% of what I wanted to do # .bashrc # Run two commands and stay logged in to new server. alias gr='ssh -t -p 5xx4x [email protected] 2> /dev/null "cd /var; ls; /bin/bash -i"' Now, after successful login / verify user logged in = root pts/0 2011-01-30 22:09 Try to 'logout' = bash: logout: not login shell: use `exit' I seem to have full root access w/o being logged into the shell? (The " /bin/bash -i " was added to 'Stay logged in' but doesn't work quite as expected) FYI: The question is "How to get this SSH login working" & it is mostly solved, sorry I made a mess... ... .. . Original Question Here: # .bashrc # Run two commands and stay logged in to new server. alias gr='ssh -t -p 5xx4x [email protected] "cd /var; ls; /bin/bash -i"' # (hack) Hide "map back to the address - POSSIBLE BREAK-IN ATTEMPT!" message. alias gr='ssh -p 5xx4x [email protected] 2> /dev/null' Both examples 'work' as shown; When I try to add the ' 2 /dev/null ' to the first example, then the whole thing breaks. I'm out of time trying to solve the warning message other ways, so is it possible to combine both examples to make example #1 work w/o the warning message? Thank you. ps. If you also know a proper way to kill the login warning message, please do tell (the 'standard' "edit host file" advice isn't working for me)

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  • linked-server sql - access

    - by user22121
    Hi, I have a SQL server 2000 and an Access database mdb connected by Linked server on the other hand I have a program in c # that updates data in a SQL table (Users) based data base access. When running my program returns the following error message: OLE DB provider 'Microsoft.Jet.OLEDB.4.0' reported an error. Authentication failed. [OLE / DB provider returned message: Can not start the application. Missing information file of the working group or is opened exclusively by another user.] OLE DB error trace [OLE / DB Provider 'Microsoft.Jet.OLEDB.4.0' IDBInitialize:: Initialize returned 0x80040E4D: Authentication failed.] . Both the program, the sql server and database access are on a remote server. On the local server the problem was solved by running the following: "sp_addlinkedsrvlogin 'ActSC', 'false', NULL, 'admin', NULL". Try on the remote server the next, without result: "sp_addlinkedsrvlogin 'ActSC', true, null, 'user', 'pass'". On the remote server and from the "Query Analyzer" sql update statements are working correctly. Can you think of what may be the problem? Thanks!

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