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  • error: invalid type argument of '->' (have 'struct node')

    - by Roshan S.A
    Why cant i access the pointer "Cells" like an array ? i have allocated the appropriate memory why wont it act like an array here? it works like an array for a pointer of basic data types. #include<stdio.h> #include<stdlib.h> #include<ctype.h> #define MAX 10 struct node { int e; struct node *next; }; typedef struct node *List; typedef struct node *Position; struct Hashtable { int Tablesize; List Cells; }; typedef struct Hashtable *HashT; HashT Initialize(int SIZE,HashT H) { int i; H=(HashT)malloc(sizeof(struct Hashtable)); if(H!=NULL) { H->Tablesize=SIZE; printf("\n\t%d",H->Tablesize); H->Cells=(List)malloc(sizeof(struct node)* H->Tablesize); should it not act like an array from here on? if(H->Cells!=NULL) { for(i=0;i<H->Tablesize;i++) the following lines are the ones that throw the error { H->Cells[i]->next=NULL; H->Cells[i]->e=i; printf("\n %d",H->Cells[i]->e); } } } else printf("\nError!Out of Space"); } int main() { HashT H; H=Initialize(10,H); return 0; } The error I get is as in the title-error: invalid type argument of '->' (have 'struct node').

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  • C++ infix to postfix conversion for logical conditions

    - by Gopalakrishnan Subramani
    I want to evaluate one expression in C++. To evaluate it, I want the expression to be converted to prefix format. Here is an example wstring expression = "Feature1 And Feature2"; Here are possible ways. expression = "Feature1 And (Feature2 Or Feature3)"; expression = "Not Feature1 Or Feature3"; Here And, Or, Not are reserved words and parentheses ("(", )) are used for scope Not has higher precedence And is set next precedence to Not Or is set to next precedence to And WHITE SPACE used for delimiter. Expression has no other elements like TAB, NEWLINE I don't need arithmetic expressions. I can do the evaluation but can somebody help me to convert the strings to prefix notation?

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  • Function pointers in Objective-C

    - by Stefan Klumpp
    I have the following scenario: Class_A - method_U - method_V - method_X - method_Y Class_B - method_M - method_N HttpClass - startRequest - didReceiveResponse // is a callback Now I want to realize these three flows (actually there are many more, but these are enough to demonstrate my question): Class_A :: method_X -> HttpClass :: startRequest:params -> ... wait, wait, wait ... -> HttpClass :: didReceiveResponse -> Class_A :: method_Y:result and: Class_A :: method_U -> HttpClass :: startRequest:params -> ... wait, wait, wait ... -> HttpClass :: didReceiveResponse -> Class_A :: method_V:result and the last one: Class_B :: method_M -> HttpClass :: startRequest:params -> ... wait, wait, wait ... -> HttpClass :: didReceiveResponse -> Class_B :: method_N:result Please note, that the methods in Class_A and Class_B have different names and functionality, they just make us of the same HttpClass. My solution now would be to pass a C function pointer to startRequest, store it in the HttpClass and when didReceiveResponse gets called I invoke the function pointer and pass the result (which will always be a JSON Dictionary). Now I'm wondering if there can be any problems using plain C or if there are better solutions doing it in a more Objective-C way. Any ideas?

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  • vector <T *> destructor

    - by Daniel.Z
    I have a class defined like: Class A { public: int num; A *parent; vector<A *> children; ... // constructor without parameters A(void) { this->num = 3; this->parent = 0; for (int i=0;i<num;++i) children.push_back(new A(this,num-1)); } // constructor with parameters A(A *a,int n) { this->num = n; this->children->parent = a; for (int i=0;i<num;++i) this->children.push_back(new A(this,this->num-1)); } }; now, the constructor works fine. there are some problem with destructor. currently, the destructor is defined as: A::~A(void) { if (this->parent!=0) this->parent = 0; for (int i=0;i<(int)children.size();++i) this->children[i]->~A(); vector <A *> ().swap(this->children); } but every time when I debug it, it will break at: void deallocate(pointer _Ptr, size_type) { // deallocate object at _Ptr, ignore size ::operator delete(_Ptr); } it looks like I cannot delete the pointer in the vector of this-children, is there any way that I can de-construct the class successfully?

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  • center div tags inside parent div

    - by Senthilnathan
    I have two div tags inside a parent div. I want to display the two divs in same line and centered. Below is the html code. <div id="parent"> <div id="addEditBtn" style="display:inline-block; vertical-align: middle; width:20px; cursor:pointer;" class="ui-state-default ui-corner-all"> <span class="ui-icon ui-icon-pencil"></span></div> <div id="deleteBtn" style="display:inline-block; vertical-align: middle; width:20px; cursor:pointer;" class="ui-state-default ui-corner-all"> <span class="ui-icon ui-icon-trash"></span></div> </div> I tried with "display:inline-block; vertical-align: middle;" but its getting aligned left. Please help me out to centered the div tags inside the parent div.

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  • Immutable classes in C++

    - by ereOn
    Hi, In one of my projects, I have some classes that represent entities that cannot change once created, aka. immutable classes. Example : A class RSAKey that represent a RSA key which only has const methods. There is no point changing the existing instance: if you need another one, you just create one. My objects sometimes are heavy and I enforced the use of smart pointers to avoid copy. So far, I have the following pattern for my classes: class RSAKey : public boost::noncopyable, public boost::enable_shared_from_this<RSAKey> { public: /** * \brief Some factory. * \param member A member value. * \return An instance. */ static boost::shared_ptr<const RSAKey> createFromMember(int member); /** * \brief Get a member. * \return The member. */ int getMember() const; private: /** * \brief Constructor. * \param member A member. */ RSAKey(int member); /** * \brief Member. */ const int m_member; }; So you can only get a pointer (well, a smart pointer) to a const RSAKey. To me, it makes sense, because having a non-const reference to the instance is useless (it only has const methods). Do you guys see any issue regarding this pattern ? Are immutable classes something common in C++ or did I just created a monster ? Thank you for your advices !

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  • Initialize Static Array of Structs in C

    - by russell_h
    I implementing a card game in C. There are lots of types of cards and each has a bunch of information, including some actions that will need to be individually scripted associated with it. Given a struct like this (and I'm not certain I have the syntax right for the function pointer) struct CARD { int value; int cost; // This is a pointer to a function that carries out actions unique // to this card int (*do_actions) (struct GAME_STATE *state, int choice1, int choice2); }; I would like to initialize a static array of these, one for each card. I'm guessing this would look something like this int do_card0(struct GAME_STATE *state, int choice1, int choice2) { // Operate on state here } int do_card1(struct GAME_STATE *state, int choice1, int choice2) { // Operate on state here } extern static struct cardDefinitions[] = { {0, 1, do_card0}, {1, 3, do_card1} }; Will this work, and am I going about this the right way at all? I'm trying to avoid huge numbers of switch statements. Do I need to define the 'do_cardN' functions ahead of time, or is there some way to define them inline in the initialization of the struct (something like a lambda function in python)? I'll need read-only access to cardDefinitions from a different file - is 'extern static' correct for that? I know this is a lot of questions rolled into one but I'm really a bit vague about how to go about this. Thanks.

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  • Indices instead of pointers in STL containers?

    - by zvrba
    Due to specific requirements [*], I need a singly-linked list implementation that uses integer indices instead of pointers to link nodes. The indices are always interpreted with respect to a vector containing the list nodes. I thought I might achieve this by defining my own allocator, but looking into the gcc's implementation of , they explicitly use pointers for the link fields in the list nodes (i.e., they do not use the pointer type provided by the allocator): struct _List_node_base { _List_node_base* _M_next; ///< Self-explanatory _List_node_base* _M_prev; ///< Self-explanatory ... } (For this purpose, the allocator interface is also deficient in that it does not define a dereference function; "dereferencing" an integer index always needs a pointer to the underlying storage.) Do you know a library of STL-like data structures (i am mostly in need of singly- and doubly-linked list) that use indices (wrt. a base vector) instead of pointers to link nodes? [*] Saving space: the lists will contain many 32-bit integers. With two pointers per node (STL list is doubly-linked), the overhead is 200%, or 400% on 64-bit platform, not counting the overhead of the default allocator.

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  • Why do I get "request for member in something not a struct or union" from this code?

    - by pyroxene
    I'm trying to teach myself C by coding up a linked list. I'm new to pointers and memory management and I'm getting a bit confused. I have this code: /* Remove a node from the list and rejiggle the pointers */ void rm_node(struct node **listP, int index) { struct node *prev; struct node *n = *listP; if (index == 0) { *listP = *listP->next; free(n); return; } for (index; index > 0; index--) { n = n->next; if (index == 2) { prev = n; } } prev->next = n->next; free(n); } to remove an element from the list. If I want to remove the first node, I still need some way of referring to the list, which is why the listP arg is a double pointer, so it can point to the first element of the list and allow me to free the node that used to be the head. However, when I try to dereference listP to access the pointer to the next node, the compiler tells me error: request for member ‘next’ in something not a structure or union . What am I doing wrong here? I think I might be hopelessly mixed up..?

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  • how to elegantly duplicate a graph (neural network)

    - by macias
    I have a graph (network) which consists of layers, which contains nodes (neurons). I would like to write a procedure to duplicate entire graph in most elegant way possible -- i.e. with minimal or no overhead added to the structure of the node or layer. Or yet in other words -- the procedure could be complex, but the complexity should not "leak" to structures. They should be no complex just because they are copyable. I wrote the code in C#, so far it looks like this: neuron has additional field -- copy_of which is pointer the the neuron which base copied from, this is my additional overhead neuron has parameterless method Clone() neuron has method Reconnect() -- which exchanges connection from "source" neuron (parameter) to "target" neuron (parameter) layer has parameterless method Clone() -- it simply call Clone() for all neurons network has parameterless method Clone() -- it calls Clone() for every layer and then it iterates over all neurons and creates mappings neuron=copy_of and then calls Reconnect to exchange all the "wiring" I hope my approach is clear. The question is -- is there more elegant method, I particularly don't like keeping extra pointer in neuron class just in case of being copied! I would like to gather the data in one point (network's Clone) and then dispose it completely (Clone method cannot have an argument though).

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  • c++-to-python swig caused memory leak! Related to Py_BuildValue and SWIG_NewPointerObj

    - by usfree74
    Hey gurus, I have the following Swig code that caused memory leak. PyObject* FindBestMatch(const Bar& fp) { Foo* ptr(new Foo()); float match; // call a function to fill the foo pointer return Py_BuildValue( "(fO)", match, SWIG_NewPointerObj(ptr, SWIGTYPE_p_Foo, 0 /* own */)); } I figured that ptr is not freed properly. So I did the following: PyObject* FindBestMatch(const Bar& fp) { Foo* ptr(new Foo()); float match; // call a function to fill the foo pointer *PyObject *o = SWIG_NewPointerObj(ptr, SWIGTYPE_p_Foo, 1 /* own */);* <------- 1 means pass the ownership to python PyObject *result = Py_BuildValue("(fO)", match, o); Py_XDECREF(o); return result; } But I am not very sure whether this will cause memory corruption. Here, Py_XDECREF(o) will decrease the ref count, which can free memory used by object "o". But o is part of the return value "result". Freeing "o" can cause data corrupt, I guess? I tried my change. It works fine and the caller (python code) does see the expected data. But this could be because nobody else overwrites to that memory area. So what's the right way to deal with memory management of the above code? I search the swig docs, but don't see very concrete description. Please help! Thanks, xin

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  • template specialization of a auto_ptr<T>

    - by Chris Kaminski
    Maybe I'm overcomplicating things, but then again, I do sort of like clean interfaces. Let's say I want a specialization of auto_ptr for an fstream - I want a default fstream for the generic case, but allow a replacement pointer? tempate <> class auto_ptr<fstream> static fstream myfStream; fstream* ptr; public: auto_ptr() { // set ptr to &myfStream; } reset(fstream* newPtr) { // free old ptr if not the static one. ptr = newPtr }; } Would you consider something different or more elegant? And how would you keep something like the above from propagating outside this particular compilation unit? [The actual template is a boost::scoped_ptr.] EDIT: It's a contrived example. Ignore the fstream - it's about providing a default instance of object for an auto_ptr. I may not want to provide a specialized instance, but would like to keep the auto_ptr semantics for this static default object. class UserClass { public: auto_ptr<fstream> ptr; UserClass() { } } I may not provide an dynamic object at construction time - I still want it to have a meaningful default. Since I'm not looking at ownership-transfer semantics, it really shouldn't matter that my pointer class is pointing to a statically allocated object, no?

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  • Can I prevent a Linux user space pthread yielding in critical code?

    - by KermitG
    I am working on an user space app for an embedded Linux project using the 2.6.24.3 kernel. My app passes data between two file nodes by creating 2 pthreads that each sleep until a asynchronous IO operation completes at which point it wakes and runs a completion handler. The completion handlers need to keep track of how many transfers are pending and maintain a handful of linked lists that one thread will add to and the other will remove. // sleep here until events arrive or time out expires for(;;) { no_of_events = io_getevents(ctx, 1, num_events, events, &timeout); // Process each aio event that has completed or thrown an error for (i=0; i<no_of_events; i++) { // Get pointer to completion handler io_complete = (io_callback_t) events[i].data; // Get pointer to data object iocb = (struct iocb *) events[i].obj; // Call completion handler and pass it the data object io_complete(ctx, iocb, events[i].res, events[i].res2); } } My question is this... Is there a simple way I can prevent the currently active thread from yielding whilst it runs the completion handler rather than going down the mutex/spin lock route? Or failing that can Linux be configured to prevent yielding a pthread when a mutex/spin lock is held?

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  • Using `<List>` when dealing with pointers in C#.

    - by Gorchestopher H
    How can I add an item to a list if that item is essentially a pointer and avoid changing every item in my list to the newest instance of that item? Here's what I mean: I am doing image processing, and there is a chance that I will need to deal with images that come in faster than I can process (for a short period of time). After this "burst" of images I will rely on the fact that I can process faster than the average image rate, and will "catch-up" eventually. So, what I want to do is put my images into a <List> when I acquire them, then if my processing thread isn't busy, I can take an image from that list and hand it over. My issue is that I am worried that since I am adding the image "Image1" to the list, then filling "Image1" with a new image (during the next image acquisition) I will be replacing the image stored in the list with the new image as well (as the image variable is actually just a pointer). So, my code looks a little like this: while (!exitcondition) { if(ImageAvailabe()) { Image1 = AcquireImage(); ImgList.Add(Image1); } if(ImgList.Count 0) { ProcessEngine.NewImage(ImgList[0]); ImgList.RemoveAt(0); } } Given the above, how can I ensure that: - I don't replace all items in the list every time Image1 is modified. - I don't need to pre-declare a number of images in order to do this kind of processing. - I don't create a memory devouring monster. Any advice is greatly appreciated.

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  • Using shared_ptr to implement RCU (read-copy-update)?

    - by yongsun
    I'm very interested in the user-space RCU (read-copy-update), and trying to simulate one via tr1::shared_ptr, here is the code, while I'm really a newbie in concurrent programming, would some experts help me to review? The basic idea is, reader calls get_reading_copy() to gain the pointer of current protected data (let's say it's generation one, or G1). writer calls get_updating_copy() to gain a copy of the G1 (let's say it's G2), and only one writer is allowed to enter the critical section. After the updating is done, writer calls update() to do a swap, and make the m_data_ptr pointing to data G2. The ongoing readers and the writer now hold the shared_ptr of G1, and either a reader or a writer will eventually deallocate the G1 data. Any new readers would get the pointer to G2, and a new writer would get the copy of G2 (let's say G3). It's possible the G1 is not released yet, so multiple generations of data my co-exists. template <typename T> class rcu_protected { public: typedef T type; typedef std::tr1::shared_ptr<type> rcu_pointer; rcu_protected() : m_data_ptr (new type()) {} rcu_pointer get_reading_copy () { spin_until_eq (m_is_swapping, 0); return m_data_ptr; } rcu_pointer get_updating_copy () { spin_until_eq (m_is_swapping, 0); while (!CAS (m_is_writing, 0, 1)) {/* do sleep for back-off when exceeding maximum retry times */} rcu_pointer new_data_ptr(new type(*m_data_ptr)); // as spin_until_eq does not have memory barrier protection, // we need to place a read barrier to protect the loading of // new_data_ptr not to be re-ordered before its construction _ReadBarrier(); return new_data_ptr; } void update (rcu_pointer new_data_ptr) { while (!CAS (m_is_swapping, 0, 1)) {} m_data_ptr.swap (new_data_ptr); // as spin_until_eq does not have memory barrier protection, // we need to place a write barrier to protect the assignments of // m_is_writing/m_is_swapping be re-ordered bofore the swapping _WriteBarrier(); m_is_writing = 0; m_is_swapping = 0; } private: volatile long m_is_writing; volatile long m_is_swapping; rcu_pointer m_data_ptr; };

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  • A trivial Python SWIG error question

    - by Alex
    I am trying to get Python running with swig to do C/C++. I am running the tutorial here, 'building a python module'. When I do the call gcc -c example.c example_wrap.c -I /my_correct_path/python2.5 I get an error: my_correct_path/python2.5/pyport.h:761:2: error: #error "LONG_BIT definition appears wrong for platform (bad gcc/glibc config?)." example_wrap.c: In function 'SWIG_Python_ConvertFunctionPtr': example_wrap.c:2034: warning: initialization discards qualifiers from pointer target type example_wrap.c: In function 'SWIG_Python_FixMethods': example_wrap.c:3232: warning: initialization discards qualifiers from pointer target type It actually does create an example.o file, but it doesn't work. I am using python2.5 not 2.1 as in the example, is this a problem? The error (everything else is just a 'warning') says something about wrong platform. This is a 64bit machine; is this a problem? Is my gcc configured wrong for my machine? How do I get past this? UPDATE: I am still having problems. How do I actually implement this "fix"?

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  • How to store and remove dynamically and automatic variable of generic data type in custum list data

    - by Vineel Kumar Reddy
    Hi I have created a List data structure implementation for generic data type with each node declared as following. struct Node { void *data; .... .... } So each node in my list will have pointer to the actual data(generic could be anything) item that should be stored in the list. I have following signature for adding a node to the list AddNode(struct List *list, void* eledata); the problem is when i want to remove a node i want to free even the data block pointed by *data pointer inside the node structure that is going to be freed. at first freeing of datablock seems to be straight forward free(data) // forget about the syntax..... But if data is pointing to a block created by malloc then the above call is fine....and we can free that block using free function int *x = (int*) malloc(sizeof(int)); *x = 10; AddNode(list,(void*)x); // x can be freed as it was created using malloc what if a node is created as following int x = 10; AddNode(list,(void*)&x); // x cannot be freed as it was not created using malloc Here we cannot call free on variable x!!!! How do i know or implement the functionality for both dynamically allocated variables and static ones....that are passed to my list.... Thanks in advance...

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  • Multithreaded linked list traversal

    - by Rob Bryce
    Given a (doubly) linked list of objects (C++), I have an operation that I would like multithread, to perform on each object. The cost of the operation is not uniform for each object. The linked list is the preferred storage for this set of objects for a variety of reasons. The 1st element in each object is the pointer to the next object; the 2nd element is the previous object in the list. I have solved the problem by building an array of nodes, and applying OpenMP. This gave decent performance. I then switched to my own threading routines (based off Windows primitives) and by using InterlockedIncrement() (acting on the index into the array), I can achieve higher overall CPU utilization and faster through-put. Essentially, the threads work by "leap-frog'ing" along the elements. My next approach to optimization is to try to eliminate creating/reusing the array of elements in my linked list. However, I'd like to continue with this "leap-frog" approach and somehow use some nonexistent routine that could be called "InterlockedCompareDereference" - to atomically compare against NULL (end of list) and conditionally dereference & store, returning the dereferenced value. I don't think InterlockedCompareExchangePointer() will work since I cannot atomically dereference the pointer and call this Interlocked() method. I've done some reading and others are suggesting critical sections or spin-locks. Critical sections seem heavy-weight here. I'm tempted to try spin-locks but I thought I'd first pose the question here and ask what other people are doing. I'm not convinced that the InterlockedCompareExchangePointer() method itself could be used like a spin-lock. Then one also has to consider acquire/release/fence semantics... Ideas? Thanks!

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  • CreateProcess() fails with an access violation

    - by John Doe
    My aim is to execute an external executable in my program. First, I used system() function, but I don't want the console to be seen to the user. So, I searched a bit, and found CreateProcess() function. However, when I try to pass a parameter to it, I don't know why, it fails. I took this code from MSDN, and changed a bit: #include <windows.h> #include <stdio.h> #include <tchar.h> void _tmain( int argc, TCHAR *argv[] ) { STARTUPINFO si; PROCESS_INFORMATION pi; ZeroMemory( &si, sizeof(si) ); si.cb = sizeof(si); ZeroMemory( &pi, sizeof(pi) ); /* if( argc != 2 ) { printf("Usage: %s [cmdline]\n", argv[0]); return; } */ // Start the child process. if( !CreateProcess( NULL, // No module name (use command line) L"c:\\users\\e\\desktop\\mspaint.exe", // Command line NULL, // Process handle not inheritable NULL, // Thread handle not inheritable FALSE, // Set handle inheritance to FALSE 0, // No creation flags NULL, // Use parent's environment block NULL, // Use parent's starting directory &si, // Pointer to STARTUPINFO structure &pi ) // Pointer to PROCESS_INFORMATION structure ) { printf( "CreateProcess failed (%d).\n", GetLastError() ); return; } // Wait until child process exits. WaitForSingleObject( pi.hProcess, INFINITE ); // Close process and thread handles. CloseHandle( pi.hProcess ); CloseHandle( pi.hThread ); } However, this code crated access violation somehow. Can I execute mspaint without showing user the console? Thank you very much.

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  • Delivering activity feed items in a moderately scalable way

    - by sotangochips
    The application I'm working on has an activity feed where each user can see their friends' activity (much like Facebook). I'm looking for a moderately scalable way to show a given users' activity stream on the fly. I say 'moderately' because I'm looking to do this with just a database (Postgresql) and maybe memcached. For instance, I want this solution to scale to 200k users each with 100 friends. Currently, there is a master activity table that stores the rendered html for the given activity (Jim added a friend, George installed an application, etc.). This master activity table keeps the source user, the html, and a timestamp. Then, there's a separate ('join') table that simply keeps a pointer to the person who should see this activity in their friend feed, and a pointer to the object in the main activity table. So, if I have 100 friends, and I do 3 activities, then the join table will then grow to 300 items. Clearly this table will grow very quickly. It has the nice property, though, that fetching activity to show to a user takes a single (relatively) inexpensive query. The other option is to just keep the main activity table and query it by saying something like: select * from activity where source_user in (1, 2, 44, 2423, ... my friend list) This has the disadvantage that you're querying for users who may never be active, and as your friend list grows, this query can get slower and slower. I see the pros and the cons of both sides, but I'm wondering if some SO folks might help me weigh the options and suggest one way or they other. I'm also open to other solutions, though I'd like to keep it simple and not install something like CouchDB, etc. Many thanks!

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  • What does it mean to pass a &variable to a function? E.g., string& insert ( size_t pos1, const strin

    - by Bob Montgomery
    I understand passing a pointer, and returning a pointer: char * strcat ( char * destination, const char * source ); You're passing a variable that contains the address to a char; returning the same. But what does it mean to pass something using the reference operator? Or to return it? string& insert ( size_t pos1, const string& str ); I mean, I understand what actually happens, I just don't understand the notation. Why isn't the notation this instead: string * insert ( size_t pos1, const string * str ); //made up I presume it has something to do with passing/returning the instance of a class, but what? Is this syntax valid; if not why not and if so what does it mean? char & strcat ( char & destination, const char & source ); //made up (all of the function declarations, except the last made-up two, are from http://www.cplusplus.com )

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  • How do I write in-code comments and documentation in a proper way? Is there any standard for this?

    - by hkBattousai
    I want to add documentation in my code by means of comment lines. Is there any standard format for this? For example, consider the code below: class Arithmetic { // This method adds two numbers, and returns the result. // dbNum1 is the first number to add, and dbNum2 is second. // The returning value is dbNum1+dbNum2. static double AddTwoNumbers(double dbNum1, double dbNum2); } For this example code, is there any better way of writing the comment lines?

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  • How to convert a list object to bigdecimal in prepared statement?

    - by user1103504
    I am using prepared statement for bulk insertion of records. Iam iterating a list which contains values and their dataTypes differ. One of the data type is BigDecimal and when i try to set calling preparedstatement, it is throwing null pointer exception. My code int count = 1; for (int j = 0; j < list.size(); j++) { if(list.get(j) instanceof Timestamp) { ps.setTimestamp(count, (Timestamp) list.get(j)); } else if(list.get(j) instanceof java.lang.Character) { ps.setString(count, String.valueOf(list.get(j))); } else if(list.get(j) instanceof java.math.BigDecimal) { ps.setBigDecimal(count, (java.math.BigDecimal)list.get(j)); } else { ps.setObject(count, list.get(j)); } count++; } I tried 2 ways to convert, casting the object and tried to create a new object of type BigDecimal ps.setBigDecimal(count, new BigDecimal(list.get(j).toString)); both donot solve my problem. It is throwing null pointer exception. help is appreciated. Thanks

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  • Which tool can list writing access to a specific variable in C?

    - by Lichtblitz
    Unfortunately I'm not even sure how this sort of static analysis is called. It's not really control flow analysis because I'm not looking for function calls and I don't really need data flow analysis because I don't care about the actual values. I just need a tool that lists the locations (file, function) where writing access to a specific variable takes place. I don't even care if that list contained lines that are unreachable. I could imagine that writing a simple parser could suffice for this task but I'm certain that there must be a tool out there that does this simple analysis. As a poor student I would appreciate free or better yet open source tools and if someone could tell me how this type of static analysis is actually called, I would be equally grateful! EDIT: I forgot to mention there's no pointer arithmetic in the code base.

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  • A programming language for teaching data structures and algorithms with? [closed]

    - by Andreas Grech
    Possible Duplicate: Choice of programming language for learning data structures and algorithms Teachers have different opinions on what programming language they would choose to teach data structures and algorithms with. Some would prefer a lower level language such as C because it allows the student to learn more about what goes on beyond the abstractions in terms of memory allocation and deallocation and pointers and pointer arithmetic. On the other hand, others would say that they would prefer a higher level language like Java because it allows the student to learn more about the concepts of the structures and the algorithm design rather than 'waste time' and fiddle around with memory segmentation faults and all the blunders that come with languages where memory management is manual. What is your take on this issue? And also, please post any references you may know of that also discuss this argument.

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