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  • Function Pointer from base class

    - by camelord
    Hi there, i need a Function Pointer from a base class. Here is the code: class CActionObjectBase { ... void AddResultStateErrorMessage( const char* pcMessage , ULONG iResultStateCode); ... } CActionObjectCalibration( ): CActionObjectBase() { ... m_Calibration = new CCalibration(&CActionObjectBase::AddResultStateErrorMessage); } class CCalibration { ... CCalibration(void (CActionObjectBase::* AddErrorMessage)(const char*, ULONG )); ... void (CActionObjectBase::* m_AddErrorMessage)(const char*, ULONG ); } Inside CCalibration in a Function occurs the Error. I try to call the Function Pointer like this: if(m_AddErrorMessage) { ... m_AddErrorMessage("bla bla", RSC_FILE_ERROR); } The Problem is, that I cannot compile. The Error Message says something like: error C2064: Expression is no Function, that takes two Arguments. What is wrong? regards camelord

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  • .net converting bytearray to double[]

    - by AJ
    Hello, I am working with a database from a legacy app which stores 24 floating point values (doubles) as a byte array of length 192, so 8 bytes per value. This byte array is stored in a column of type image in a SQL Server 2005 database. In my .net app I need to read this byte array and convert it to a array of type Double[24]. I can access the field easy enough reader.GetBytes(...) but how to convert the returned ByteArray to Double[24] Any ideas? Thanks, AJ

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  • C: Cannot declare pointer inside if statement

    - by echedey lorenzo
    Hi, I have a pointer which points to a function. I would like to: if (mode == 0) { const unsigned char *packet = read_serial_packet(src, &len); } else { const unsigned char *packet = read_network_packet(fd, &len); } But I cannot do it because my compiler complains when I first use the pointer later in the code. error: 'packet' undeclared (first use in this function) This is strange. It worked without the if statement, but now I need my program to be able to get data from different sources. Isn't it possible to do this? I think so. If it isn't, is there any other simple way to get what I am trying? Thanks a lot.

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  • Databinding to type double - decimal mark lost

    - by user1277327
    I have a project where I'm databinding a gridview to a list, where one column is databound to a gridview. The problem I have is that with the double being 5.5 on one computer it appears as 5.5 in the gridview. But on another it looks like 55, the decimal mark dissapears. So 3.14 will look like 314 etc. The error occurs with the following code: myDatagrid.ItemsSource = someList; Binding binding = new Binding("DoubleValue"); myColumnInDatagrid.Binding = binding; I've also tried using a very simple valueconverter, that just return the double, and parsed it in ConvertBack. I'm pretty new to WPF so I'm sorry if I've made some obvious mistakes, I just don't understand why it works on one computer but not on the other. Perhaps it should be noted that both of the computers use the same operating system, with the same language settings (afaik at least).

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  • Get pointer to member function from within member function in C++

    - by Eli
    Currently in the program I am attempting to write I need to be able to get a pointer to a member function within a member function of the same class. The pointer needs to be passed to a function as a void (*)(). Example: //CallFunc takes a void (*)() argument class testClass { public: void aFunc2; void aFunc1; } void testClass:aFunc2(){ callFunc(this.*aFunc1); // How should this be done? } void testClass:aFunc1(){ int someVariable = 1; } I'm trying to do this in GCC 4.0.1. Also, the member function being called can't be static because it references non-static variables in the class that it is part of.

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  • declaring a 2D array of pointer objects

    - by Tyler Stennette
    I'm having a tough time figuring out how to instantiate a 2D array of pointer objects. Here is how I'm doing it: Pieces* chessBoard[9][9]; When I want to set it to an actual object pointer, I'm doing the following: chessBoard[1][1] = new Rook(p1Rook); Rook is a class that inherits attributes from the Pieces class and p1Rook is a char variable set to 'R'. This class also implements virtual functions (not pure virtual) from Pieces such as move() or getPiece() that are unique to the particular chess piece. However, when I compile my program, I get the following error: ChessBoard.cpp:69: error: expected type-specifier before ‘Rook’ ChessBoard.cpp:69: error: cannot convert ‘int*’ to ‘Pieces*’ in assignment Can someone please explain what I should change to get rid of this rather annoying persistent error? I would appreciate it.

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  • Inline assembler get address of pointer Visual Studio

    - by Joe
    I have a function in VS where I pass a pointer to the function. I then want to store the pointer in a register to further manipulate. How do you do that? I have tried void f(*p) { __asm mov eax, p // try one FAIL __asm mov eax, [p] // try two FAIL __asm mov eax, &p // try three FAIL } Both 1 and 2 are converted to the same code and load the value pointed to. I just want the address. Oddly, option 1 works just fine with integers. void f() { int i = 5; __asm mov eax, i // SUCCESS? }

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  • C 64-bit Pointer Alignment

    - by DuneBug
    Are pointers on a 64-bit system still 4 byte aligned (similar to a double on a 32 bit system)? Or are they note 8 byte aligned? For example, on a 64-bit system how big is the following data structure: struct a { void* ptr; char myChar; } Would the pointer by 8 byte aligned, causing 7 bytes of padding for the character (total = 8 + 8 = 16)? Or would the pointer be 4 byte aligned (4 bytes + 4 bytes) causing 3 bytes of padding (total = 4 + 4 + 4 = 12)? Thanks, Ryan

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  • Inline assembler getaddress of pointer Visual Studio

    - by Joe
    I have a function in VS where I pass a pointer to the function. I then want to store the pointer in a register to further manipulate. How do you do that? I have tried void f(*p) { __asm mov eax, p // try one FAIL __asm mov eax, [p] // try two FAIL __asm mov eax, &p // try three FAIL } Both 1 and 2 are converted to the same code and load the value pointed to. I just want the address. Oddly, option 1 works just fine with integers. void f() { int i = 5; __asm mov eax, i // SUCCESS? }

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  • best way to output a full precision double into a text file

    - by flevine100
    Hi, I need to use an existing text file to store some very precise values. When read back in, the numbers essentially need to be exactly equivalent to the ones that were originally written. Now, a normal person would use a binary file... for a number of reasons, that's not possible in this case. So... do any of you have a good way of encoding a double as a string of characters (aside from increasing the precision). My first thought was to cast the double to a char[] and write out the chars. I don't think that's going to work because some of the characters are not visible, produce sounds, and even terminate strings ('\0'... I'm talkin to you!) Thoughts?

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  • Compilation hangs for a class with field double d = 2.2250738585072012e-308

    - by 01es
    I have come across an interesting situation. A coworker committed some changes, which would not compile on my machine neither from the IDE (Eclipse) nor from a command line (Maven). The problem manifested in the compilation process taking 100% CPU and only killing the process would help to stop it. After some analysis the cause of the problem was located and resolved. It turned out be a line "double d = 2.2250738585072012e-308" (without semicolon at the end) in one of the interfaces. The following snipped duplicates it. public class WeirdCompilationIssue { double d = 2.2250738585072012e-308 } Why would compiler hang? A language edge case?

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  • Perl Regular expression remove double tabs, line breaks, white spaces

    - by Scoox
    Hi guys, I want to write a perl script that removes double tabs, line breaks and white spaces. What I have so far is: $txt=~s/\r//gs; $txt=~s/ +/ /gs; $txt=~s/\t+/\t/gs; $txt=~s/[\t\n]*\n/\n/gs; $txt=~s/\n+/\n/gs; But, 1. It's not beautiful. Should be possible to do that with far less regexps. 2. It just doesn't work and I really do not know why. It leaves some double tabs, white spaces and empty lines (i.e. lines with only a tab or whitespace) I could solve it with a while, but that is very slow and ugly. Any suggestions?

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  • Why does C++ mandate that complex only be instantiated for float, double, or long double?

    - by templatetypedef
    According to the C++ ISO spec, §26.2/2: The effect of instantiating the template complex for any type other than float, double or long double is unspecified. Why would the standard authors explicitly add this restriction? This makes it unspecified, for example, what happens if you make complex<int> or a complex<MyCustomFixedPointType> and seems like an artificial restriction. Is there a reason for this limitation? Is there a workaround if you want to instantiate complex with your own custom type? I'm primarily asking this question because of this earlier question, in which the OP was confused as to why abs was giving bizarre outputs for complex<int>. That said, this still doesn't quite make sense given that we also might want to make complex numbers out of fixed-points types, higher-precision real numbers, etc. Thanks!

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  • In .net, how do I choose between a Decimal and a Double

    - by Ian Ringrose
    We were discussing this the other day at work and I wish there was a Stackoverflow question I would point people at so here goes.) What is the difference between a Double and a Decimal? When (in what cases) should you always use a Double? When (in what cases) should you always use a Decimal? What’s the diver factors to consider in cases that don’t fall into one of the two camps above? (There a lot of questions that overlap this question, but they tend to be asking what someone should do in a given case, not how to decide in the general case)

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  • How to I reference a pointer from a different class

    - by Justagruvn
    Hey team of awesomeness!, (Iphone Objective-C question) First off, I despise singletons with a passion. Though I should probably be trying to use one, I just dont want to. I want to create a data class (that is instantiated only once by a view controller on loading), and then using a different class, message the crap out of that data instance until it is brimming with so much data, it smiles. So, how do i do that? I made a pointer to the instance of the data class when I instantiated it. I'm now over in a separate view controller, action occurs, and I want to update the initial data object. I think I need to reference that object by way of pointer, but I have no idea how to do that. yes I've set properties and getters and setters, which seem to work, but only in the initial view controller class. Peace Love applesauce.

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