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  • Using a Function returning apointer as LValue

    - by Amrish
    Why cant I used a function returning a pointer as a lvalue? For example this one works int* function() { int* x; return x; } int main() { int* x = function(); x = new int(9); } but not this int* function() { int* x; return x; } int main() { int* x; function() = x; } While I can use a pointer variable as a lvalue, why can't I use a function returning a pointer as a lvalue? Also, when the function returns a refernce, instead of a pointer, then it becomes a valid lvalue.

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  • Lvalue required error [migrated]

    - by ankur.trapasiya
    While working with pointers i wrote the following code, int main() { int a[]={10,20,30,40,50}; int i; for(i=0;i<5;i++) { printf("\n%d",*a); a++; } return 0; } Now as per my understanding array name itself is an address in c and the pointer arithmetic done is here is correct as per my knowledge. But when i try to run the code it is giving me "Lvalue Required" error. So what is the exact reason for occuring Lvalue required error because before this also i have come across situations where this error is there. Secondly why the arithmetic on the pointer is not legal here in this case?

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  • Opening Macro definitions: tdfx_span.c: lvalue required as left operand of assignment

    - by anttir
    Hi, I'm trying to compile X11R6-7.0 under Ubuntu maverick and got some weird compilation errors I'm unable to resolve myself. I needed X11R6-7.0 as ati catalyst drivers don't support newer xorg and oss drivers don't support 3d acceleration of my hardware. Anyone know what this error message means? I know some C but I got a bit confused. Does it mean GET_FB_DATA macro returned NULL or some method/property not set? Any further insight how to "debug" preprocessor definitions at this point would be great. I don't think I can print anything useful with #error. The error I get: tdfx_span.c: In function ‘tdfxDDWriteDepthPixels’: tdfx_span.c:976: error: lvalue required as left operand of assignment tdfx_span.c:1008: error: lvalue required as left operand of assignment tdfx_span.c: In function ‘write_stencil_pixels’: tdfx_span.c:1242: error: lvalue required as left operand of assignment the Code: 958- switch (depth_size) { 959- case 16: 960- GetBackBufferInfo(fxMesa, &backBufferInfo); 961- /* 962- * Note that the _LOCK macro adds a curly brace, 963- * and the UNLOCK macro removes it. 964- */ 965- WRITE_FB_SPAN_LOCK(fxMesa, info, 966- GR_BUFFER_AUXBUFFER, GR_LFBWRITEMODE_ANY); 967- { 968- LFBParameters ReadParams; 969- GetFbParams(fxMesa, &info, &backBufferInfo, 970- &ReadParams, sizeof(GLushort)); 971- for (i = 0; i < n; i++) { 972- if (mask[i] && visible_pixel(fxMesa, x[i], y[i])) { 973- xpos = x[i] + fxMesa->x_offset; 974- ypos = bottom - y[i]; 975- d16 = depth[i]; 976: PUT_FB_DATA(&ReadParams, GLushort, xpos, ypos, d16); 977- } 978- } 979- } 980- WRITE_FB_SPAN_UNLOCK(fxMesa, GR_BUFFER_AUXBUFFER); 981- break; 982- case 24: And relative macros: #define GET_FB_DATA(ReadParamsp, type, x, y) \ (((x) < (ReadParamsp)->firstWrappedX) \ ? (((type *)((ReadParamsp)->lfbPtr)) \ [(y) * ((ReadParamsp)->LFBStrideInElts) \ + (x)]) \ : (((type *)((ReadParamsp)->lfbWrapPtr)) \ [((y)) * ((ReadParamsp)->LFBStrideInElts) \ + ((x) - (ReadParamsp)->firstWrappedX)])) #define GET_ORDINARY_FB_DATA(ReadParamsp, type, x, y) \ (((type *)((ReadParamsp)->lfbPtr)) \ [(y) * ((ReadParamsp)->LFBStrideInElts) \ + (x)]) #define GET_WRAPPED_FB_DATA(ReadParamsp, type, x, y) \ (((type *)((ReadParamsp)->lfbWrapPtr)) \ [((y)) * ((ReadParamsp)->LFBStrideInElts) \ + ((x) - (ReadParamsp)->firstWrappedX)]) #define PUT_FB_DATA(ReadParamsp, type, x, y, value) \ (GET_FB_DATA(ReadParamsp, type, x, y) = (type)(value)) #define PUT_ORDINARY_FB_DATA(ReadParamsp, type, x, y, value) \ (GET_ORDINARY_FB_DATA(ReadParamsp, type, x, y) = (type)(value)) #define PUT_WRAPPED_FB_DATA(ReadParamsp, type, x, y, value) \ (GET_WRAPPED_FB_DATA(ReadParamsp, type, x, y) = (type)(value)) The LFBParameters Struct 483-typedef struct 484-{ 485- void *lfbPtr; 486- void *lfbWrapPtr; 487- FxU32 LFBStrideInElts; 488- GLint firstWrappedX; 489-} 490:LFBParameters; Thanks for looking.

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  • A reference that is not to 'const' cannot be bound to a non-lvalue

    - by Bert
    Hello, Am struggling a bit with this. Am declaring: BYTE *pImage = NULL; Used in call: m_pMyInterface-GetImage(i, &imageSize, &pImage); Visual C++ 2003 compiler error: error C2664: 'CJrvdInterface::GetImage' : cannot convert parameter 3 from 'BYTE **__w64 ' to 'BYTE **& ' A reference that is not to 'const' cannot be bound to a non-lvalue The method called is defined as: void CMyInterface::GetImage(const int &a_iTileId, ULONG *a_pulImageSize, BYTE** &a_ppbImage) { (...) Any help much appreciated, Bert

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  • Can you return an assignable lvalue in Scala?

    - by Alex R
    (note, lvalue is actually a term from the C grammar, I don't know what it's called in Scala!) Trying to learn Scala... this evening I'm working on an internal DSL for a dynamically scoped language that might resemble PHP syntax. My REPL is: Welcome to Scala version 2.7.6.final (Java HotSpot(TM) Client VM, Java 1.6.0). I have some made-up example code: class $(any: Any) { def update(sym: Symbol, any: Any) { println("line 2 executed");} def -(sym: Symbol) : $ = { println("line 1 executed"); return this } def update(any: Any) { println("line 3 executed");} } The following works as expected: scala var a = new $(0) a: $ = $@19238ad scala a('x) = "blah" line 2 executed On the other hand, why does the following not invoke the 1-parameter update method? scala a = 1 :6: error: type mismatch; found : Int(1) required: $ a = 1 ^ Ultimately, I would like this to work: a-'x = "blah" Thanks

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  • getting error in perl :can't modify non-lvalue subroutine call

    - by dexter
    i have index.pl and subs.pl when i run the program user inserts date of birth and then it is passed to getage() subroutine in subs.pl . subs.pl has many subroutines. getage() than implicitly calls another subroutine called validate() which validates the date entered by user. when i run the index.pl user enters the date as: 03-04-2005 following error comes :can't modify non-lvalue subroutine call at subs.pl line 85, < line 1 and at 85th line of subs.pl i have list(my $val,my @value) = validate($dob); why such error comes any solutions

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  • Solving C++ 'target of assignment not really an lvalue' errors

    - by Jason
    Given this code: void FrMemCopy(void *to, const void *from, size_t sz) { size_t sz8 = sz >> 3; size_t sz1 = sz - (sz8 << 3); while (sz8-- != 0) { *((double *)to)++ = *((double *)from)++; } while (sz1-- != 0) { *((char *)to)++ = *((char *)from)++; } } I am receiving target of assignment not really an lvalue warnings on the 2 lines inside the while loops. Can anyone break down those lines? a cast then an increment? What is a simplier way to write that? What does the error mean?

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  • trying to make a simple grid-class, non-lvalue in assignment

    - by Tyrfing
    I'm implementing a simple C++ grid class. One Function it should support is accessed through round brackets, so that I can access the elements by writing mygrid(0,0). I overloaded the () operator and i am getting the error message: "non-lvalue in assignment". what I want to be able to do: //main cGrid<cA*> grid(5, 5); grid(0,0) = new cA(); excerpt of my implementation of the grid class: template class cGrid { private: T* data; int mWidth; int mHeight; public: cGrid(int width, int height) : mWidth(width), mHeight(height) { data = new T[width*height]; } ~cGrid() { delete data; } T operator ()(int x, int y) { if (x >= 0 && x <= mWidth) { if (y >= 0 && y <= mHeight) { return data[x + y * mWidth]; } } } const T &operator ()(int x, int y) const { if (x >= 0 && x <= mWidth) { if (y >= 0 && y <= mHeight) { return data[x + y * mWidth]; } } } The rest of the code deals with the implementation of an iterator and should not be releveant.

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  • can't increment Glib::ustring::iterator (getting "invalid lvalue in increment" compiler error)

    - by davka
    in the following code: int utf8len(char* s, int len) { Glib::ustring::iterator p( string::iterator(s) ); Glib::ustring::iterator e ( string::iterator(s+len) ); int i=0; for (; p != e; p++) // ERROR HERE! i++; return i; } I get the compiler error on the for line, which is sometimes "invalid lvalue in increment", and sometimes "ISO C++ forbids incrementing a pointer of type etc... ". Yet, the follwing code: int utf8len(char* s) { Glib::ustring us(s); int i=0; for (Glib::ustring::iterator p = us.begin(); p != us.end(); p++) i++; return i; } compiles and works fine. according the Glib::ustring documentation and the include file, ustring iterator can be constructed from std::string iterator, and has operator++() defined. Weird? BONUS QUESTION :) Is there a difference in C++ between the 2 ways of defining a variable: classname ob1( initval ); classname ob1 = initval; I believed that they are synonymous; yet, if I change Glib::ustring::iterator p( string::iterator(s) ); to Glib::ustring::iterator p = string::iterator(s); I get a compiler error (gcc 4.1.2) conversion from ‘__gnu_cxx::__normal_iterator, std::allocator ’ to non-scalar type ‘Glib::ustring_Iterator<__gnu_cxx::__normal_iterator, std::allocator ’ requesed thanks a lot!

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  • Objective C LValue required as unary '&' operand

    - by Bob
    Hello! In my code, I get this error when I try to get a pointer to my class property. (I wrote a small *.OBJ file translator in Python, discarding the normals) CODE: //line: line of text const char *str = [line UTF8String]; Point3D *p1, *p2, *p3; p1 = [Point3D makeX:0 Y:0 Z:0]; p2 = [Point3D makeX:0 Y:0 Z:0]; p3 = [Point3D makeX:0 Y:0 Z:0]; sscanf(str, "t %f,%f,%f %f,%f,%f %f,%f,%f",(&[p1 x]),&([p1 y]),&([p1 z]),&([p2 x]),&([p2 y]),&([p2 z]),&([p3 x]),&([p3 y]),&([p3 z])); Triangle3D *tri = [Triangle3D make:p1 p2:p2 p3:p3];

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  • Difference between c++11 vs c++03

    - by aiao
    I have spend a few hours about rvalue s and lvalue. Here is what I understand int main() { //..... Foo foo = Bar1(); Foo foo = Bar2(); //...... } Foo Bar1() { //Do something return foo; } Foo& Bar2() { //Do something return foo; } Under c++03, Bar1() would copy the return object (just before return), and then return the address of the copied object; executing a wasteful copy of an object which is about to be destroyed. Bar2() would return the object created within the function. Under c++11, Bar1() and Bar2() would essentially be equivalent (and also equivalent to Bar2() of c++03). Is that right? If not, please elaborate.

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  • C++0x rvalue references - lvalues-rvalue binding

    - by Doug
    This is a follow-on question to http://stackoverflow.com/questions/2748866/c0x-rvalue-references-and-temporaries In the previous question, I asked how this code should work: void f(const std::string &); //less efficient void f(std::string &&); //more efficient void g(const char * arg) { f(arg); } It seems that the move overload should probably be called because of the implicit temporary, and this happens in GCC but not MSVC (or the EDG front-end used in MSVC's Intellisense). What about this code? void f(std::string &&); //NB: No const string & overload supplied void g1(const char * arg) { f(arg); } void g2(const std::string & arg) { f(arg); } It seems that, based on the answers to my previous question that function g1 is legal (and is accepted by GCC 4.3-4.5, but not by MSVC). However, GCC and MSVC both reject g2 because of clause 13.3.3.1.4/3, which prohibits lvalues from binding to rvalue ref arguments. I understand the rationale behind this - it is explained in N2831 "Fixing a safety problem with rvalue references". I also think that GCC is probably implementing this clause as intended by the authors of that paper, because the original patch to GCC was written by one of the authors (Doug Gregor). However, I don't this is quite intuitive. To me, (a) a const string & is conceptually closer to a string && than a const char *, and (b) the compiler could create a temporary string in g2, as if it were written like this: void g2(const std::string & arg) { f(std::string(arg)); } Indeed, sometimes the copy constructor is considered to be an implicit conversion operator. Syntactically, this is suggested by the form of a copy constructor, and the standard even mentions this specifically in clause 13.3.3.1.2/4, where the copy constructor for derived-base conversions is given a higher conversion rank than other implicit conversions: A conversion of an expression of class type to the same class type is given Exact Match rank, and a conversion of an expression of class type to a base class of that type is given Conversion rank, in spite of the fact that a copy/move constructor (i.e., a user-defined conversion function) is called for those cases. (I assume this is used when passing a derived class to a function like void h(Base), which takes a base class by value.) Motivation My motivation for asking this is something like the question asked in http://stackoverflow.com/questions/2696156/how-to-reduce-redundant-code-when-adding-new-c0x-rvalue-reference-operator-over ("How to reduce redundant code when adding new c++0x rvalue reference operator overloads"). If you have a function that accepts a number of potentially-moveable arguments, and would move them if it can (e.g. a factory function/constructor: Object create_object(string, vector<string>, string) or the like), and want to move or copy each argument as appropriate, you quickly start writing a lot of code. If the argument types are movable, then one could just write one version that accepts the arguments by value, as above. But if the arguments are (legacy) non-movable-but-swappable classes a la C++03, and you can't change them, then writing rvalue reference overloads is more efficient. So if lvalues did bind to rvalues via an implicit copy, then you could write just one overload like create_object(legacy_string &&, legacy_vector<legacy_string> &&, legacy_string &&) and it would more or less work like providing all the combinations of rvalue/lvalue reference overloads - actual arguments that were lvalues would get copied and then bound to the arguments, actual arguments that were rvalues would get directly bound. Questions My questions are then: Is this a valid interpretation of the standard? It seems that it's not the conventional or intended one, at any rate. Does it make intuitive sense? Is there a problem with this idea that I"m not seeing? It seems like you could get copies being quietly created when that's not exactly expected, but that's the status quo in places in C++03 anyway. Also, it would make some overloads viable when they're currently not, but I don't see it being a problem in practice. Is this a significant enough improvement that it would be worth making e.g. an experimental patch for GCC?

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  • How can I make this function act like an l-value?

    - by BeeBand
    Why can't I use the function ColPeekHeight() as an l-value? class View { public: int ColPeekHeight(){ return _colPeekFaceUpHeight; } void ColPeekHeight( int i ) { _colPeekFaceUpHeight = i; } private: int _colPeekFaceUpHeight; }; ... { if( v.ColPeekHeight() > 0.04*_heightTable ) v.ColPeekHeight()-=peek; } The compiler complains at v.ColPeekHeight()-=peek. How can I make ColPeekHeight() an l-value?

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  • how to assign to the names() attribute of the value of a variable in R

    - by Tony
    In R, "assign('x',v)" sets the object whose name is 'x' to v. Replace 'x' by the result of applying a text function to a variable x. Then "assign" shows its worth. Unfortunately, "assign(paste('names(','x',')',sep=''),v)" fails. So if 'x' is a variable x, I can set its value, but I can't give it names for its elements. Can one work around this? a parse-eval trick maybe? Thanks.

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  • Rvalues in C++03

    - by DeadMG
    How can you tell whether or not a given parameter is an rvalue in C++03? I'm writing some very generic code and am in need of taking a reference if possible, or constructing a new object otherwise. Can I overload to take by-value as well as by-reference and have the rvalue returns call the by-value function? Or do I have a very sickening feeling that this is why rvalue references are in C++0x?

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  • Perfect Forwarding to async lambda

    - by Alexander Kondratskiy
    I have a function template, where I want to do perfect forwarding into a lambda that I run on another thread. Here is a minimal test case which you can directly compile: #include <thread> #include <future> #include <utility> #include <iostream> #include <vector> /** * Function template that does perfect forwarding to a lambda inside an * async call (or at least tries to). I want both instantiations of the * function to work (one for lvalue references T&, and rvalue reference T&&). * However, I cannot get the code to compile when calling it with an lvalue. * See main() below. */ template <typename T> std::string accessValueAsync(T&& obj) { std::future<std::string> fut = std::async(std::launch::async, [](T&& vec) mutable { return vec[0]; }, std::forward<T>(obj)); return fut.get(); } int main(int argc, char const *argv[]) { std::vector<std::string> lvalue{"Testing"}; // calling with what I assume is an lvalue reference does NOT compile std::cout << accessValueAsync(lvalue) << std::endl; // calling with rvalue reference compiles std::cout << accessValueAsync(std::move(lvalue)) << std::endl; // I want both to compile. return 0; } For the non-compiling case, here is the last line of the error message which is intelligible: main.cpp|13 col 29| note: no known conversion for argument 1 from ‘std::vector<std::basic_string<char> >’ to ‘std::vector<std::basic_string<char> >&’ I have a feeling it may have something to do with how T&& is deduced, but I can't pinpoint the exact point of failure and fix it. Any suggestions? Thank you! EDIT: I am using gcc 4.7.0 just in case this could be a compiler issue (probably not)

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  • How to use void*

    - by Rondogiannis Aristophanes
    I am imlementing a simple merge function and I have got stuck, as the compiler gives me errors that I cannot explain. Here is my merge function: void merge(void *a, int beg, int middle, int end, int (*cmp)(const void*, const void* { std::stack<void*> first; std::stack<void*> second; for(int i = beg; i < middle; i++) { first.push(a+i); } for(int i = middle; i < end; i++) { second.push(a+i); } for(int i = beg; i < end; i++) { if(first.empty()) { void *tmp = second.top(); second.pop(); a+i = tmp; } else if(second.empty()) { void *tmp = first.top(); first.pop(); a+i = tmp; } else if(cmp(first.top(), second.top())) { void *tmp = first.top(); first.pop(); a+i = tmp; } else { void *tmp = second.top(); second.pop(); a+i = tmp; } } } And here is the error: sort.h: In function `void merge(void*, int, int, int, int (*)(const void*, const void*))': sort.h:9: error: pointer of type `void *' used in arithmetic sort.h:12: error: pointer of type `void *' used in arithmetic sort.h:19: error: pointer of type `void *' used in arithmetic sort.h:19: error: non-lvalue in assignment sort.h:23: error: pointer of type `void *' used in arithmetic sort.h:23: error: non-lvalue in assignment sort.h:27: error: pointer of type `void *' used in arithmetic sort.h:27: error: non-lvalue in assignment sort.h:31: error: pointer of type `void *' used in arithmetic sort.h:31: error: non-lvalue in assignment Can anyone help me? TIA.

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  • C++0x rvalue references and temporaries

    - by Doug
    (I asked a variation of this question on comp.std.c++ but didn't get an answer.) Why does the call to f(arg) in this code call the const ref overload of f? void f(const std::string &); //less efficient void f(std::string &&); //more efficient void g(const char * arg) { f(arg); } My intuition says that the f(string &&) overload should be chosen, because arg needs to be converted to a temporary no matter what, and the temporary matches the rvalue reference better than the lvalue reference. This is not what happens in GCC and MSVC. In at least G++ and MSVC, any lvalue does not bind to an rvalue reference argument, even if there is an intermediate temporary created. Indeed, if the const ref overload isn't present, the compilers diagnose an error. However, writing f(arg + 0) or f(std::string(arg)) does choose the rvalue reference overload as you would expect. From my reading of the C++0x standard, it seems like the implicit conversion of a const char * to a string should be considered when considering if f(string &&) is viable, just as when passing a const lvalue ref arguments. Section 13.3 (overload resolution) doesn't differentiate between rvalue refs and const references in too many places. Also, it seems that the rule that prevents lvalues from binding to rvalue references (13.3.3.1.4/3) shouldn't apply if there's an intermediate temporary - after all, it's perfectly safe to move from the temporary. Is this: Me misreading/misunderstand the standard, where the implemented behavior is the intended behavior, and there's some good reason why my example should behave the way it does? A mistake that the compiler vendors have somehow all made? Or a mistake based on common implementation strategies? Or a mistake in e.g. GCC (where this lvalue/rvalue reference binding rule was first implemented), that was copied by other vendors? A defect in the standard, or an unintended consequence, or something that should be clarified?

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  • Argument type deduction, references and rvalues

    - by uj2
    Consider the situation where a function template needs to forward an argument while keeping it's lvalue-ness in case it's a non-const lvalue, but is itself agnostic to what the argument actually is, as in: template <typename T> void target(T&) { cout << "non-const lvalue"; } template <typename T> void target(const T&) { cout << "const lvalue or rvalue"; } template <typename T> void forward(T& x) { target(x); } When x is an rvalue, instead of T being deduced to a constant type, it gives an error: int x = 0; const int y = 0; forward(x); // T = int forward(y); // T = const int forward(0); // Hopefully, T = const int, but actually an error forward<const int>(0); // Works, T = const int It seems that for forward to handle rvalues (without calling for explicit template arguments) there needs to be an forward(const T&) overload, even though it's body would be an exact duplicate. Is there any way to avoid this duplication?

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  • Error on writing data to DVD

    - by sijith
    Hi, From past 1 week i stuck on this please help me i am attaching code. bool DVDBurner::Burner() { m_hResult = CoCreateInstance(__uuidof(MsftDiscFormat2Data), NULL, CLSCTX_INPROC_SERVER, __uuidof(IDiscFormat2Data), (void**)&m_discFormatData); if (!SUCCEEDED(m_hResult)) { qDebug()<<"Unable to Initialize IDiscFormat2Data "; return false; } m_hResult = CoCreateInstance(__uuidof(MsftDiscRecorder2), NULL, CLSCTX_INPROC_SERVER, __uuidof(IDiscRecorder2), (void**)&m_discRecorder); if (FAILED(m_hResult)) { qDebug()<<"Unable to Initialize IDiscRecorder2 Data "; return false; } BSTR bstrDeviceName; HRESULT hr = S_OK; BOOL bComInitialised; UINT iCounter = 0; LONG lValue = 0; LONG iCount; bComInitialised = SUCCEEDED(CoInitializeEx(0, COINIT_MULTITHREADED)); // Create an object of IDiscMaster2 if (SUCCEEDED(hr)){ CoCreateInstance( CLSID_MsftDiscMaster2, NULL, CLSCTX_ALL, IID_PPV_ARGS(&discMaster) ); if(FAILED(hr)){ qDebug()<<"\nUnsuccessful in creating an instance of CLSID_MsftDiscMaster2.\n\nError returned: 0x%x\n"<<hr; return 0; } } /////////////////////////// Get the number of drives/////////////////////////////// if (SUCCEEDED(hr)){ hr = discMaster->get_Count(&lValue); if (SUCCEEDED(hr)){ printf("lValue %d\n\n",lValue); } } ////////////////////////// Print all the optical drives attached to the system//// if (SUCCEEDED(hr)){ for(iCount = 0; iCount < lValue; iCount++) { hr = discMaster->get_Item(iCount, &bstrDeviceName); qDebug()<<"\nUnique identifier of the disc device associated with index"<< iCount<< bstrDeviceName; } } m_hResult = m_discRecorder->InitializeDiscRecorder(bstrDeviceName); if (!SUCCEEDED(m_hResult)) { qDebug()<<"IDiscFormat2Data->InitializeDiscRecorder Failed "; return false; } LPCWSTR pszFile=L"D:\\Test\\output.txt"; ULONGLONG mediaSize = 0; mediaSize=GetSizeOnDisc(pszFile); IStream* dataStream = NULL; if (dataStream == NULL) { SHCreateStreamOnFileEx(pszFile, STGM_READ|STGM_SHARE_DENY_NONE|STGM_DELETEONRELEASE, FILE_ATTRIBUTE_NORMAL, FALSE,NULL, &dataStream); } m_hResult = m_discFormatData->put_Recorder(GetInterface()); if (!SUCCEEDED(m_hResult)) { qDebug()<<"IDiscFormat2Data->put_Recorder Failed ";return false;} char *ansistr = "DVDBurner"; int a = lstrlenA(ansistr); BSTR unicodestr = SysAllocStringLen(NULL, a); ::MultiByteToWideChar(CP_ACP, 0, ansistr, a, unicodestr, a); m_hResult = m_discFormatData->put_ClientName(unicodestr); if (FAILED(m_hResult)){qDebug()<<"Unable to put_ClientName(buf_bstr)";return false;} m_hResult = m_discFormatData->Write(dataStream); // Here i am getting error 0xc0aa0403 if (FAILED(m_hResult)){printf("Unable to m_discFormatData- >Write::::Error:0x%08x",m_hResult); return false;} discMaster->Release(); CoUninitialize(); bComInitialised = FALSE; return 0; } ULONGLONG DVDBurner::GetSizeOnDisc(LPCWSTR pszFile) { CFileStatus status; if (CFile::GetStatus(pszFile, status)) { if (status.m_size > 0) { return ((status.m_size / SECTOR_SIZE) + 1) * SECTOR_SIZE; } } return 0; }

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  • GLSL compile error when accessing an array with compile-time constant index

    - by Benlitz
    I have this shader that works well on my computer (using an ATI HD 5700). I have a loop iterating between two constant values, which is, afaik, acceptable in a glsl shader. I write stuff in two arrays in this loop. #define NB_POINT_LIGHT 2 ... varying vec3 vVertToLight[NB_POINT_LIGHT]; varying vec3 vVertToLightWS[NB_POINT_LIGHT]; ... void main() { ... for (int i = 0; i < NB_POINT_LIGHT; ++i) { if (bPointLightUse[i]) { vVertToLight[i] = ConvertToTangentSpace(ShPointLightData[i].Position - WorldPos.xyz); vVertToLightWS[i] = ShPointLightData[i].Position - WorldPos.xyz; } } ... } I tried my program on another computer equipped with an nVidia GTX 560 Ti, and it fails to compile my shader. I get the following errors (94 and 95 are the lines of the two affectations) when calling glLinkProgram: Vertex info ----------- 0(94) : error C5025: lvalue in assignment too complex 0(95) : error C5025: lvalue in assignment too complex I think my code is valid, I don't know if this comes from a compiler bug, a conversion of my shader to another format from the compiler (nvidia looks to convert it to CG), or if I just missed something. I already tried to remove the if (bPointLightUse[i]) statement and I still have the same error. However, if I just write this: vVertToLight[0] = ConvertToTangentSpace(ShPointLightData[0].Position - WorldPos.xyz); vVertToLightWS[0] = ShPointLightData[0].Position - WorldPos.xyz; vVertToLight[1] = ConvertToTangentSpace(ShPointLightData[1].Position - WorldPos.xyz); vVertToLightWS[1] = ShPointLightData[1].Position - WorldPos.xyz; Then I don't have the error anymore, but it's really unconvenient so I would prefer to keep something loop-based. Here is the more detailled config that works: Vendor: ATI Technologies Inc. Renderer: ATI Radeon HD 5700 Series Version: 4.1.10750 Compatibility Profile Context Shading Language version: 4.10 And here is the more detailed config that doesn't work (should also be compatibility profile, although not indicated): Vendor: NVIDIA Corporation Renderer: GeForce GTX 560 Ti/PCI/SSE2 Version: 4.1.0 Shading Language version: 4.10 NVIDIA via Cg compiler

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  • In what circumstances are instance variables declared as '_var' in 'use fields' readonly?

    - by Pedro Silva
    I'm trying to understand the behavior of the fields pragma, which I find poorly documented, regarding fields prefixed with underscores. This is what the documentation has to say about it: Field names that start with an underscore character are made private to the class and are not visible to subclasses. Inherited fields can be overridden but will generate a warning if used together with the -w switch. This is not consistent with its actual behavior, according to my test, below. Not only are _-prefixed fields visible within a subclass, they are visible within foreign classes as well (unless I don't get what 'visible' means). Also, directly accessing the restricted hash works fine. Where can I find more about the behavior of the fields pragma, short of going at the source code? { package Foo; use strict; use warnings; use fields qw/a _b __c/; sub new { my ( $class ) = @_; my Foo $self = fields::new($class); $self->a = 1; $self->b = 2; $self->c = 3; return $self; } sub a : lvalue { shift->{a} } sub b : lvalue { shift->{_b} } sub c : lvalue { shift->{__c} } } { package Bar; use base 'Foo'; use strict; use warnings; use Data::Dumper; my $o = Bar->new; print Dumper $o; ##$VAR1 = bless({'_b' => 2, '__c' => 3, 'a' => 1}, 'Foo'); $o->a = 4; $o->b = 5; $o->c = 6; print Dumper $o; ##$VAR1 = bless({'_b' => 5, '__c' => 6, 'a' => 4}, 'Foo'); $o->{a} = 7; $o->{_b} = 8; $o->{__c} = 9; print Dumper $o; ##$VAR1 = bless({'_b' => 8, '__c' => 9, 'a' => 7}, 'Foo'); }

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