C# :: Why Can't A Constant Field Be Of Non-built-in Struct Type
Dec 9, 2011
Code:
class T
{
enum E { }
struct S { }
interface I { }
delegate void D();
class C { }
}
[code]....
All of the above are possible except the constant field of a type that is a struct. I can see why the non-string reference types would default to the only literal expression they can represent - null - and if I'm not mistaken the default value of a struct is an instance of the struct with all its fields set to their default value, but why is it that a const struct field is not possible? is there a reason why or is it just the way c# was written? oh and by the way, what's the idea of allowing enum types to have a default constructor?
WAVEFORMATEX InputTest::StandardWaveFormat { //Instantiate WaveFormat -- PCM standards StandardWaveFormat.wFormatTag = WAVE_FORMAT_PCM; StandardWaveFormat.cbSize = 0; //extra information sent over stream. Usually ignored in PCM format.
[Code] ....
I get the following errors starting with the header file:
Error1error C2146: syntax error : missing ';' before identifier 'StandardWaveFormat' Error2error C4430: missing type specifier - int assumed. Note: C++ does not support default-int
both associated with the "const WAVEFORMATEX StandardWaveFormat; " line.
Here's a link to the WAVEFORMATEX struct: [URL] .....
Then the cpp source code is probably way off. Let me know if you'd like to see the errors associated with that.
I'm writing a class "Property" for a program that manages different types of properties. This is my .h for y base class. I was trying to write a virtual void function to convert different children classes to strings that can be displayed, but Xcode is freaking out.
I had it as:
virtual void toString()= 0;
and it gave me an error message: "Virtual can only exist in non-static member functions" and "field has incomplete type 'void'"
I changed it to:
virtual string toString() = 0;
and the error message didn't change.
Is this an issue with Xcode or did I do something wrong? Even after changing it to string it told me that it "has incomplete type 'void'"....
class DataBase { // Change the connection path here to your own version of the database public SqlConnection con = new SqlConnection(@"Data Source=(LocalDB)v11.0;AttachDbFilename=|DataDirectory|UberDatabase.mdf;Integrated Security=True;"); public DataBase() { } }
And in the same namespace as this class I have a form that calls it like so:
DataBase dBase = new DataBase(); SqlCommand trythis = new SqlCommand("Register", dBase.con);
However, I'm getting the field initializer error on dBase.con. I'm not sure why, but when I call the database from another file (program.cs) it works fine this way.
I'm working on a program where I have a vector full of <myClassType> structs.
I'm trying to insert items into a vector, searching first through the vector to make sure the value isn't already in the vector before inserting it. The "find" function isn't working properly.
I keep getting C2678 "binary '==': no operator found which takes a left-hand operand of type "myClassType" or there is no conversion errors in Visual Studio 2010.
I know it's something having to do with the find function and my iterators, but I can't, for the life of me, figure out what it is.
I've tried switching to const_iterators, but I get the same error message.
I am trying to make a automated menu. It shows there are no syntax errors but when compiled it says cannot convert choice from type into to menuItemType. I am not sure what I did wrong. Here is the code
I am trying to compile the files below. The PosLin.cpp contains the SurTriAuto and SurTriPosRotAndQ functions below. Before adding SurTriPosRotAndQ, it compiled fine, but when I added SurTriPosRotAndQ, I am getting "invalid use of incomplete type ‘struct PosRotAndQ" error messages
I was thinking I could try moving SurTriAuto and SurTriPosRotAndQ to PosLin.h, but since they return "T*", I'm not sure what to do
I have a "t.h" file
namespace TNS { class T {
[Code]....
when I add "include Pos/PL.h" to geopar.h, I get an error saying v.hpp is missing, where v.hpp is part of a 3rd-party software and it is already in my directory
I've been reading the tutorials on Friendship and Inheritance [URL] ..... but I still don't understand why I can't access members of the same struct type.
The code above is located in a source file, where the function isAlphanumeric passes a char value, and Message is the struct containing the string I want to access. Below is the declaration of the struct and string located in the corresponding header file.
My frustration comes when I try to call and assign messageText like the tutorial does to its private members, but I keep getting an error saying I can't access the string because it is a private member. Is there a way to access the string without having to pass it through the function wordBeginsAt?
I have created a shared object in Ubuntu (libMYLIB.so). I am now trying to compile a simple test program (testmylib.c) to see if the shared object is properly built. I am getting an error that the build cannot find the shared object. My build command is:
I have a few VC2008 projects whose solutions also includes deployment projects, in which the primary output of several DLLs are included along with the primary apps EXE file. These DLLs are all part of the solution. Now because of the way I do my DLLs, which for lack of better phrase I'll call a true DYNAMIC link (the .LIB file can be discarded), and because I'm careful to ensure full backward compatibility in any new DLL versions, I would like to tell my deployment project to ALWAYS replace existing DLLS with the new versions, or at least offer a choice if it shouldn't be done unconditionally. Unfortunately it never seems to do that!
I'm being careful to create new overall project versions within the deployment project itself, as well as keeping my version resources, attached to each DLL up to date, and always do a full rebuild of everything in the solution (including the DLLs) prior to building the deployment project. But time and again the old DLLs stay un-updated after the install, and the person running it would have no way to know that without examining the target directories and examining file dates and/or versions. A customer shouldn't have to go through all that. I've gotten into the habit of instructing installers to fully un-install old versions before installing a new one, but as you probably know uninstalling from the control panel won't remove shared DLLs.
I was starting to think maybe the latest DLLs weren't being included in the deployment project at all. But if I manually delete those DLLS and do the install, the latest greatest are then always placed.
If I can't find a setting in the deployment project to change this behavior, I'll have to write a separate little console app to force delete (or at least archive) all the relevant DLLs as a pre-installation step. Or maybe supply a BATCH file to do all that, and run the install last. But it seems like a reasonable thing that a setting to make a deployment (MSI) file unconditionally overwrite DLLS, whose version or creation date is newer, ought to be an obvious feature. But if such an option exists, I've missed it completely.
I was attempting something weired with address to move data around when I discovered that the size of the array is not what I expected. I am passing this structure as &Users to a function that declares it as a void *, then I can deal with chunks of data (memmove) and not have to worry about index or things like that. However...sizeof is returning something I do not understand.
#include <iostream> class Hello { public: void Test() {
[Code].....
As i know a non-constant member function cant be called inside a constant member function but how the above code has been compiled successfully and giving the expected result .
I'm trying to write a simple program that extract the FAT information from a FAT32 virtual Hard Disk.I have the following structures regarding the FAT format:
Code:
//BOOT RECORD typedef struct NF_BOOT_RECORD { unsigned char BS_jumpBoot[3]; //EB 58 90 = JUMP 58 NOP (Jumps to boot code). Also E9 is acceptable. unsigned char BS_OEMName[8]; //Either MSWIN4.1 or mkdosfs unsigned short BS_BytesPerSec; //Little endian. The size of a sector. 128,256,512,1024... unsigned char BS_SecPerClus; //The number of sectors per cluster (1 CLUSTER = BPS*SPC BYTES) unsigned short BS_RsvdSecCnt; //The boot sectors (this) are included. That makes at least 1. }
[code]...
Everything seems to work fine. Mostly. The only problem, is that the program gives me the following output:BS_NumFATs shouldn't be 0. In fact, I've checked inside the structure memory, and the information seems correct. BS_NumFATs is 0x02, not 0x00 (It's the byte at offset 0x10, starting at 0x00).
I've checked the order of the structure fields, and their types, comparing them to the FAT specification given by Microsoft (File fatgen103.pdf), and it seems fine, unless I'm missing something. So I don't know why it gives 0 instead of 2, if I'm missing something.It's a Win32 program compiled with GCC version 4.4.0
I wrote a script that generates n random pixel positions and draws them to the screen. Works well. Now i tried to rotate them. Rotating does work too. But it does not work as i planned it.
paramters 'angle' and 'timestep' work somehow, but not as they should do. the function 'move' is supposed to rotate the pixelfield 'angle' degrees in a given direction, addicted to the 'timestep' parameter. 'timestep' is needed time for drawing in one single game loop.
rotation point is the middle of the screen. when i set angle to 10 it should rotate 10 degrees / second. Instead it's rotating very very fast and all stars are moving nearer to the center of the screen, so after x rounds there is just 1 pixel left in the middle of the screen. there is a kind of gravition.I'm working with SDL2. What I did find out:
FPS is <= 60, 'cause of the 'SDL_RENDERER_PRESENTVSYNC' flag. When i skip that flag, for any reason the 'gravition' would take more time. FPS is <= 1400 then, 'though i got a natural game loop (i hope):
