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• How can I create an executable to run on a certain processor architecture (instead of certain OS)?

  - by CrazyJugglerDrummer

  So I take my C++ program in Visual studio, compile, and it'll spit out a nice little EXE file. But EXEs will only run on windows, and I hear a lot about how C/C++ compiles into assembly language, which is runs directly on a processor. The EXE runs with the help of windows, or I could have a program that makes an executable that runs on a mac. But aren't I compiling C++ code into assembly language, which is processor specific? My Insights: I'm guessing I'm probably not. I know there's an Intel C++ compiler, so would it make processor-specific assembly code? EXEs run on windows, so they advantage of tons of things already set up, from graphics packages to the massive .NET framework. A processor-specific executable would be literally starting from scratch, with just the instruction set of the processor. Would this executable be a file-type? We could be running windows and open it, but then would control switch to processor only? I assume this executable would be something like an operating system, in that it would have to be run before anything else was booted up, and have only the processor instruction set to "use".

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• Enforce strong type checking in C (type strictness for typedefs)

  - by quinmars

  Is there a way to enforce explicit cast for typedefs of the same type? I've to deal with utf8 and sometimes I get confused with the indices for the character count and the byte count. So it be nice to have some typedefs: typedef unsigned int char_idx_t; typedef unsigned int byte_idx_t; With the addition that you need an explicit cast between them: char_idx_t a = 0; byte_idx_t b; b = a; // compile warning b = (byte_idx_t) a; // ok I know that such a feature doesn't exist in C, but maybe you know a trick or a compiler extension (preferable gcc) that does that. EDIT: I still don't really like the Hungarian notation in general, I couldn't used it for this problem because of project coding conventions, but I used it now in another similar case, where also the types are the same and the meanings are very similar. And I have to admit: it helps. I never would go and declare every integer with a starting "i", but as in Joel's example for overlapping types, it can be life saving.

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• how avoids deadlock condition

  - by rima

  Hi I try to write a program like a compiler.In this case I must simulate these codes of SQLPL(This one can be just for example).for example in command prompt i wana do these: c:\> sqlplus .... Enter User-Name:(here we must enter username) xxxx Enter password:(same up)yyyyy ... sql>(now i want to send my sql command to shell)prompt "rima"; "rima" [<-output] sql> prompt "xxxx" sql> exit very simple. I try to use this code: ProcessStartInfo psi = new ProcessStartInfo( @"sqlplus"); psi.UseShellExecute = false; psi.CreateNoWindow = true; psi.RedirectStandardInput = true; psi.RedirectStandardOutput = true; //psi.RedirectStandardError = true; Process process = new Process(); process.StartInfo = psi; bool started = process.Start(); if (started) { process.StandardInput.WriteLine("user/password"); process.StandardInput.Flush(); string ret = process.StandardOutput.ReadLine(); // <-- stalls here System.Console.WriteLine("sqlplus says :" + ret + "\"."); } i find out it form here but as if u read this code has problem!DEADLOCK Condition problem! this is my second time i ask my question,every time my knowledge growing,but i cant get how I can solve my problem at last!!! So I kindly kiss your hand,please help me,these process is not clear for me.any one can give me a code that handle my problem?Already i look at all codes,also I try to use ProcessRunner that in my last post some one offer me,but I cant use it also,i receive an error. I hope by first example u find out what i want,and solve the second code problem... thanks I use C# for implemantation

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• Error when compiling a WinForms project that uses SubSonic library

  - by Mike Devenney

  The code generation is working but I get the following errors when I try to build the project: Error 4 Source file '...Project Path...\Structs.cs' could not be opened ('Unspecified error ') PPSGenerator Error 5 Source file '...Project Path...\Context.cs' could not be opened ('Unspecified error ') PPSGenerator Error 6 Source file '...Project Path...\ActiveRecord.cs' could not be opened ('Unspecified error ') PPSGenerator Error 7 Source file '...Project Path...\StoredProcedures.cs' could not be opened ('Unspecified error ') PPSGenerator I'm using VS2010 on a Windows 7 64 bit machine. Project is targeting Framework 3.5... any ideas? Also noticed the following warnings, but not sure that these are as important: Warning 1 The C# 2.0 and C# 3.5 compilers are no longer supported. Templates will always be compiled with the version 4 compiler instead of 'v3.5' as specified. ...ProjectPath...\Structs.tt 1 4 Warning 2 Multiple template directives were found in the template. All but the first one will be ignored. Multiple parameters to the template directive should be specified within one template directive. ...ProjectPath...\Settings.ttinclude 1 4 Warning 3 Compiling transformation: The variable 'parameters' is assigned but its value is never used ...ProjectPath...\SQLServer.ttinclude 92 15 Thanks! Mike D

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• c incompatible types in assignment, problem with pointers?

  - by Fantastic Fourier

  Hi I'm working with C and I have a question about assigning pointers. struct foo { int _bar; char * _car[MAXINT]; // this is meant to be an array of char * so that it can hold pointers to names of cars } int foofunc (void * arg) { int bar; char * car[MAXINT]; struct foo thing = (struct foo *) arg; bar = arg->_bar; // this works fine car = arg->_car; // this gives compiler errors of incompatible types in assignment } car and _car have same declaration so why am I getting an error about incompatible types? My guess is that it has something to do with them being pointers (because they are pointers to arrays of char *, right?) but I don't see why that is a problem. when i declared char * car; instead of char * car[MAXINT]; it compiles fine. but I don't see how that would be useful to me later when I need to access certain info using index, it would be very annoying to access that info later. in fact, I'm not even sure if I am going about the right way, maybe there is a better way to store a bunch of strings instead of using array of char *?

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• (x86) Assembler Optimization

  - by Pindatjuh

  I'm building a compiler/assembler/linker in Java for the x86-32 (IA32) processor targeting Windows. High-level concepts of a "language" (in essential a Java API for creating executables) are translated into opcodes, which then are wrapped and outputted to a file. The translation process has several phases, one is the translation between languages: the highest-level code is translated into the medium-level code which is then translated into the lowest-level code (probably more than 3 levels). My problem is the following; if I have higher-level code (X and Y) translated to lower-level code (x, y, U and V), then an example of such a translation is, in pseudo-code: x + U(f) // generated by X + V(f) + y // generated by Y (An easy example) where V is the opposite of U (compare with a stack push as U and a pop as V). This needs to be 'optimized' into: x + y (essentially removing the "useless" code) My idea was to use regular expressions. For the above case, it'll be a regular expression looking like this: x:(U(x)+V(x)):null, meaning for all x find U(x) followed by V(x) and replace by null. Imagine more complex regular expressions, for more complex optimizations. This should work on all levels. What do you suggest? What would be a good approach to optimize in these situations?

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• Why are virtual methods considered early bound?

  - by AspOnMyNet

  One definition of binding is that it is the act of replacing function names with memory addresses. a) Thus I assume early binding means function calls are replaced with memory addresses during compilation process, while with late binding this replacement happens during runtime? b) Why are virtual methods also considered early bound (thus the target method is found at compile time, and code is created that will call this method)? As far as I know, with virtual methods the call to actual method is resolved only during runtime and not compile time?! thanx EDIT: 1) A a=new A(); a.M(); As far as I know, it is not known at compile time where on the heap (thus at which memory address ) will instance a be created during runtime. Now, with early binding the function calls are replaced with memory addresses during compilation process. But how can compiler replace function call with memory address, if it doesn’t know where on the heap will object a be created during runtime ( here I’m assuming the address of method a.M will also be at same memory location as a )? 2) v-table calls are neither early nor late bound. Instead there's an offset into a table of function pointers. The offset is fixed at compile time, but which table the function pointer is chosen from depends on the runtime type of the object (the object contains a hidden pointer to its v-table), so the final function address is found at runtime. But assuming the object of type T is created via reflection ( thus app doesn’t even know of existence of type T ), then how can at compile time exist an entry point for that type of object?

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• Static library not included in resulting LLVM executable

  - by Matthew Glubb

  Hi, I am trying to compile a c program using LLVM and I am having trouble getting some static libraries included. I have successfully compiled those static libraries using LLVM and, for example, libogg.a is present, as is ogg.l.bc. However, when I try to build the final program, it does not include the static ogg library. I've tried various compiler options with the most notable being: gcc oggvorbis.c -O3 -Wall -I$OV_DIR/include -l$OV_DIR/lib/libogg.a -l$OV_DIR/lib/libvorbis.a -o test.exe This results in the following output (directories shortened for brevity): $OV_DIR/include/vorbis/vorbisfile.h:75: warning: ‘OV_CALLBACKS_DEFAULT’ defined but not used $OV_DIR/include/vorbis/vorbisfile.h:82: warning: ‘OV_CALLBACKS_NOCLOSE’ defined but not used $OV_DIR/include/vorbis/vorbisfile.h:89: warning: ‘OV_CALLBACKS_STREAMONLY’ defined but not used $OV_DIR/include/vorbis/vorbisfile.h:96: warning: ‘OV_CALLBACKS_STREAMONLY_NOCLOSE’ defined but not used llvm-ld: warning: Cannot find library '$OV_DIR/lib/ogg.l.bc' llvm-ld: warning: Cannot find library '$OV_DIR/lib/vorbis.l.bc' WARNING: While resolving call to function 'main' arguments were dropped! I find this perplexing because $OV_DIR/lib/ogg.l.bc DOES exit, as does vorbis.l.bc and they are both readable (as are their containing directories) by everyone. Does anyone have any idea with what I am doing wrong? Thanks, Matt

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• Why are my Flex resource bundles not being loaded?

  - by Chris R

  I have an Actionscript module in the flex source folder filterModules, which is one of two additional source folders in my project (the main source folder is reports, but I'm not dealing with anything in there right now). Here's the MXML content that references the resources. ... This array is assigned to the dataProvider field of a ComboBox. It's not bound using the bindings, presumably for reasons that made sense to the original developer, and it'd be nontrivial to change the class to make that happen. I additionally have a resource property file in a folder resources/en_US and I have the source folder resources/{locale} in the project source settings. My additional compiler options are -locale en_US. The resource property file is resources/en_US/labels.properties (All paths are relative to the flash builder project root) and contains (amongst other things) these keys: metric.q3 = Overall Satisfaction metric.q5 = Personnel metric.q9a = Issue Resolution metric.q42 = Visit Duration Sat metric.q34 = Visit Duration I have written some FlexUnit tests that run in my local Flash Player that exercise these resources -- they check that every label is represented in the metrics array, for example, so I know that the resource file is loaded when run locally. However, when I copy the module .swf file over to my server, the combo box to which the array is assigned is empty. I copy the .swf like so, if it matters: rsync -rlDv --inplace -T /tmp ~/projects/flex_reports/bin-debug/rankingFilter.swf HOSTNAME:WEBROOT/flashPath/ Why is this? I am not able to debug the remote module because our surrounding site sets up a lot of context and makes some database calls to determine which module to load. I'm hoping to get some pointers on why resource bundles might not show up. I'd understand it if the array was present with wrong labels, but the array is instead completely empty, which is pretty odd.

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• How do I merge multiple PDB files ?

  - by blue.tuxedo

  We are currently using a single command line tool to build our product on both Windows and Linux. Si far its works nicely, allowing us to build out of source and with finer dependencies than what any of our previous build system allowed. This buys us great incremental and parallel build capabilities. To describe shortly the build process, we get the usual: .cpp -- cl.exe --> .obj and .pdb multiple .obj and .pdb -- cl.exe --> single .dll .lib .pdb multiple .obj and .pdb -- cl.exe --> single .exe .pdb The msvc C/C++ compiler supports it adequately. Recently the need to build a few static libraries emerged. From what we gathered, the process to build a static library is: multiple .cpp -- cl.exe --> multiple .obj and a single .pdb multiple .obj -- lib.exe --> a single .lib The single .pdb means that cl.exe should only be executed once for all the .cpp sources. This single execution means that we can't parallelize the build for this static library. This is really unfortunate. We investigated a bit further and according to the documentation (and the available command line options): cl.exe does not know how to build static libraries lib.exe does not know how to build .pdb files Does anybody know a way to merge multiple PDB files ? Are we doomed to have slow builds for static libraries ? How do tools like Incredibuild work around this issue ?

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• {DCC Warning} W1036 Variable '$frame' might not have been initialized?

  - by Gad D Lord

  Any ideas why I get this warning in Delphi XE: [DCC Warning] Form1.pas(250): W1036 Variable '$frame' might not have been initialized procedure TForm1.Action1Execute(Sender: TObject); var Thread: TThread; begin ... Thread := TThread.CreateAnonymousThread( procedure{Anonymos}() procedure ShowLoading(const Show: Boolean); begin /// <------------- WARNING IS GIVEN FOR THIS LINE (line number 250) Thread.Synchronize(Thread, procedure{Anonymous}() begin ... Button1.Enabled := not Show; ... end ); end; var i: Integer; begin ShowLoading(true); try Thread.Synchronize(Thread, procedure{Anonymous}() begin ... // some UI updates end Thread.Synchronize(Thread, procedure{Anonymous}() begin ... // some UI updates end ); finally ShowLoading(false); end; end ).NameThread('Some Thread Name'); Thread.Start; end; I do not have anywhere in my code a variable names frame nor $frame. I am even not sure how $frame with $ sign can be a valid identifier. Smells like compiler magic to me. PS: Of course the real life xosw is having other than Form1, Button1, Action1 names.

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• VB.NET switching from ADO.NET to LINQ

  - by Cj Anderson

  I'm VERY new to Linq. I have an application I wrote that is in VB.NET 2.0. Works great, but I'd like to switch this application to Linq. I use ADO.NET to load XML into a datatable. The XML file has about 90,000 records in it. I then use the Datatable.Select to perform searches against that Datatable. The search control is a free form textbox. So if the user types in terms it searches instantly. Any further terms that are typed in continue to restrict the results. So you can type in Bob, or type in Bob Barker. Or type in Bob Barker Price is Right. The more criteria typed in the more narrowed your result. I bind the results to a gridview. Moving forward what all do I need to do? From a high level, I assume I need to: 1) Go to Project Properties -- Advanced Compiler Settings and change the Target framework to 3.5 from 2.0. 2) Add the reference to System.XML.Linq, Add the Imports statement to the classes. So I'm not sure what the best approach is going forward after that. I assume I use XDocument.Load, then my search subroutine runs against the XDocument. Do I just do the standard Linq query for this sort of repeated search? Like so: var people = from phonebook in doc.Root.Elements("phonebook") where phonebook.Element("userid") = "whatever" select phonebook; Any tips on how to best implement?

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• Error loading shared libraries

  - by user459811

  Hi, I'm running eclipse on Ubuntu using a g++ compiler and I'm trying to run a sample program that utilizes xerces. The build produced no errors however, when i attempted to run the program, I would receive this error: "error while loading shared libraries: libxerces-c-3.1.so: cannot open shared object file: No such file or directory" libxerces-c-3.1.so is in the directory /opt/lib which I have included as a library in eclipse. The file is there when I checked the folder. When I perform an 'echo $LD_LIBRARY_PATH', /opt/lib is also listed. Any ideas into where the problem lies? Thanks. An 'ldd libxerces-c-3.1.so' command yields the following output: linux-vdso.so.1 => (0x00007fffeafff000) libnsl.so.1 => /lib/libnsl.so.1 (0x00007fa3d2b83000) libpthread.so.0 => /lib/libpthread.so.0 (0x00007fa3d2966000) libstdc++.so.6 => /usr/lib/libstdc++.so.6 (0x00007fa3d265f000) libm.so.6 => /lib/libm.so.6 (0x00007fa3d23dc000) libc.so.6 => /lib/libc.so.6 (0x00007fa3d2059000) libgcc_s.so.1 => /lib/libgcc_s.so.1 (0x00007fa3d1e42000) /lib64/ld-linux-x86-64.so.2 (0x00007fa3d337d000)

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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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• Stack usage with MMX intrinsics and Microsoft C++

  - by arik-funke

  I have an inline assembler loop that cumulatively adds elements from an int32 data array with MMX instructions. In particular, it uses the fact that the MMX registers can accommodate 16 int32s to calculate 16 different cumulative sums in parallel. I would now like to convert this piece of code to MMX intrinsics but I am afraid that I will suffer a performance penalty because one cannot explicitly intruct the compiler to use the 8 MMX registers to accomulate 16 independent sums. Can anybody comment on this and maybe propose a solution on how to convert the piece of code below to use intrinsics? == inline assembler (only part within the loop) == paddd mm0, [esi+edx+8*0] ; add first & second pair of int32 elements paddd mm1, [esi+edx+8*1] ; add third & fourth pair of int32 elements ... paddd mm2, [esi+edx+8*2] paddd mm3, [esi+edx+8*3] paddd mm4, [esi+edx+8*4] paddd mm5, [esi+edx+8*5] paddd mm6, [esi+edx+8*6] paddd mm7, [esi+edx+8*7] ; add 15th & 16th pair of int32 elements esi points to the beginning of the data array edx provides the offset in the data array for the current loop iteration the data array is arranged such that the elements for the 16 independent sums are interleaved.

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• Please take a stab at this VB.Net Oracle-related sample and help me with String.Format.

  - by Hamish Grubijan

  If the database is not Oracle, it is MS SQl 2008. My task: if Oracle, add two more parameters when calling a stored proc. Oracle and MSFT stored procs are generated; Oracle ones have 3 extra parameters: Vret_val out number, Vparam2 in out number, Vparam3 in out number, ... the rest (The are not actually named Vparam2 and Vparam3, but this should not matter). So, the code for a helper VB.Net class that calls a stored proc: Imports System.Data.Odbc Imports System.Configuration Dim objCon As OdbcConnection = Nothing Dim objAdapter As OdbcDataAdapter Dim cmdCommand As New OdbcCommand Dim objDataTable As DataTable Dim sconnection As String Try sconnection = mConnectionString objAdapter = New OdbcDataAdapter objCon = New OdbcConnection(sconnection) objCon.Open() objAdapter.SelectCommand = cmdCommand objAdapter.SelectCommand.Connection = objCon objAdapter.SelectCommand.CommandType = CommandType.StoredProcedure objAdapter.SelectCommand.CommandTimeout = Globals.mReportTimeOut If Not mIsOracle Then objAdapter.SelectCommand.CommandText = String.Format("{{call {0}}}", spName) Else Dim returnValue As New OdbcParameter returnValue.Direction = ParameterDirection.Output returnValue.ParameterName = "@Vret_val" returnValue.OdbcType = OdbcType.Numeric objAdapter.SelectCommand.Parameters.Add(returnValue) objAdapter.SelectCommand.CommandText = String.Format("{{call {0}(?)}}", spName) End If Try objDataTable = New DataTable(spName) objAdapter.Fill(objDataTable) Catch ex As Exception ... Question: I am puzzled as to what String.Format("{{call {0}(?)}}", spName) does, in particular the (?) part. My understanding of the String.Format is that it will simply replace {0} with spName. The {{, }}, and (?) do throw me off because { reminds me of formatting, (?) hints at some advanced regex use. Unfortunately I am getting little help from a key person who is on vacation without a leash [smart]phone. I am guessing that I simply add 5 more lines for each additional parameter, and change String.Format("{{call {0}(?)}}", spName) to String.Format("{{call {0}(?,?,?)}}", spName). I forgot to mention that I am coding this "blindly" - I have a compiler to help me, but no environment set up to test this. This will be over in a few days, but I need to do my best to try finishing it on time :) Thanks.

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• Why does one of these statements compile in Scala but not the other?

  - by Jeff

  (Note: I'm using Scala 2.7.7 here, not 2.8). I'm doing something pretty simple -- creating a map based on the values in a simple, 2-column CSV file -- and I've completed it easily enough, but I'm perplexed at why my first attempt didn't compile. Here's the code: // Returns Iterator[String] private def getLines = Source.fromFile(csvFilePath).getLines // This doesn't compile: def mapping: Map[String,String] = { Map(getLines map { line: String => val pairArr = line.split(",") pairArr(0) -> pairArr(1).trim() }.toList:_*) } // This DOES compile def mapping: Map[String,String] = { def strPair(line: String): (String,String) = { val pairArr = line.split(",") pairArr(0) -> pairArr(1).trim() } Map(getLines.map( strPair(_) ).toList:_*) } The compiler error is CsvReader.scala:16: error: value toList is not a member of (St ring) = (java.lang.String, java.lang.String) [scalac] possible cause: maybe a semicolon is missing before `value toList'? [scalac] }.toList:_*) [scalac] ^ [scalac] one error found So what gives? They seem like they should be equivalent to me, apart from the explicit function definition (vs. anonymous in the nonworking example) and () vs. {}. If I replace the curly braces with parentheses in the nonworking example, the error is "';' expected, but 'val' found." But if I remove the local variable definition and split the string twice AND use parens instead of curly braces, it compiles. Can someone explain this difference to me, preferably with a link to Scala docs explaining the difference between parens and curly braces when used to surround method arguments?

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• Can I cross compile with gcc for an old version of a Linux distro on my Ubuntu 9.10?

  - by Johan

  Hi, I have some old hardware with an old version of say SuSE linux running on it. Now I have this fancy development machine running Ubuntu 9.10. Some of the tools I use to compile my C app (written in Python 2.6.x) are not available on the old SuSe box. So... is it possible to compile for that old machine on my dev box? I have the following steps in mind, but would like to cross-check before venturing off into this quest: 1. Find out which static/shared libs my app needs and find/build target version of them 2. Also find the corresponding header files 3. Feed the correct flags to gcc to use the target headers and libraries 4. Feed the correct flags to gcc to use the correct architecture (i386/i686), or do I need a cross-compilation toolchain. 5. Compile, upload and enjoy ;-) I regularly use avr-gcc and cc65, both are cross compiling. I know that you set up a coss compiler for developing something like a gumstix, so it should be possible to do the same for old/other Linux distros, not? C

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• Destructors not called when native (C++) exception propagates to CLR component

  - by Phil Nash

  We have a large body of native C++ code, compliled into DLLs. Then we have a couple of dlls containing C++/CLI proxy code to wrap the C++ interfaces. On top of that we have C# code calling into the C++/CLI wrappers. Standard stuff, so far. But we have a lot of cases where native C++ exceptions are allowed to propagate to the .Net world and we rely on .Net's ability to wrap these as System.Exception objects and for the most part this works fine. However we have been finding that destructors of objects in scope at the point of the throw are not being invoked when the exception propagates! After some research we found that this is a fairly well known issue. However the solutions/ workarounds seem less consistent. We did find that if the native code is compiled with /EHa instead of /EHsc the issue disappears (at least in our test case it did). However we would much prefer to use /EHsc as we translate SEH exceptions to C++ exceptions ourselves and we would rather allow the compiler more scope for optimisation. Are there any other workarounds for this issue - other than wrapping every call across the native-managed boundary in a (native) try-catch-throw (in addition to the C++/CLI layer)?

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• Diamond problem in C++

  - by Jack

  I know the diamond problem. I am using gcc compiler. I have some scenarios I need explanation about. 1) class A{ public: virtual void eat(){cout<<"A eat\n";} }; class B:public A{ public: void eat(){ cout<<"B eat\n";}}; class C:public A{ public: void eat(){ cout<<"C eat\n";}}; class D:public B,C{ public: void eat(){ cout<<"D eat\n";}}; int main() { A * a = new D(); a->eat(); getch(); return 0; } Why doesn't this work? 2) class A{ public: void eat(){cout<<"A eat\n";} }; class B:virtual public A{ public: void eat(){ cout<<"B eat\n";}}; class C:virtual public A{ public: void eat(){ cout<<"C eat\n";}}; class D: public B,C{ public: void eat(){ cout<<"D eat\n";}}; int main() { A * a = new D(); a->eat(); getch(); return 0; } When I do this what happens in the background. How does the ambiguity get removed. Is the concept of vtables involved here?

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• If Then Else Statement Condition Being Ignored?

  - by Matma

  I think im going mad but can some show me what im missing, it must be some stupidly simple i just cant see the wood for the trees. BOTH side of this if then else statement are being executed? Ive tried commenting out the true side and moving the condition to a seperate variable with the same result. However if i explicitly set the condition to 1=0 or 1=1 then the if then statement is operating as i would expect. i.e. only executing one side of the equation... The only time ive seen this sort of thing is when the compiler has crashed and is no longer compiling (without visible indication that its not) but ive restarted studio with the same results, ive cleaned the solution, built and rebuilt with no change? please show me the stupid mistake im making using vs2005 if it matters. Dim dset As DataSet = New DataSet If (CboCustomers.SelectedValue IsNot Nothing) AndAlso (CboCustomers.SelectedValue <> "") Then Dim Sql As String = "Select sal.SalesOrderNo As SalesOrder,cus.CustomerName,has.SerialNo, convert(varchar,sal.Dateofpurchase,103) as Date from [dbo].[Customer_Table] as cus " & _ " inner join [dbo].[Hasp_table] as has on has.CustomerID=cus.CustomerTag " & _ " inner join [dbo].[salesorder_table] as sal On sal.Hasp_ID =has.Hasp_ID Where cus.CustomerTag = '" & CboCustomers.SelectedValue.ToString & "'" Dim dap As SqlDataAdapter = New SqlDataAdapter(Sql, FormConnection) dap.Fill(dset, "dbo.Customer_Table") DGCustomer.DataSource = dset.Tables("dbo.Customer_Table") Else Dim erm As String = "wtf" End If

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• TypeScript - separating code output

  - by Andrea Baccega

  i'm trying typescript and I find it very useful. I've a quite large project and i was considering rewriting it using typescript. The main problem here is the following: file A.ts: class A extends B { // A stuff } file B.ts: class B { // B stuff } If I compile A.ts with this command: tsc --out compiledA.js A.ts I'll get error from the compiler cause he doesn't know how to threat the "B" after extends. So, a "solution" would be including in A.ts (as first line of code): /// <reference path="./B.ts" /> Compiling again A.ts with the same command tsc --out compiledA.js A.ts Will result in compiledA.js containing both B.ts and A.ts code. ( which could be very nice ) In my case, I only need to compile the A.ts code in the compiledA.js file and I don't want the B.ts stuff to be in there. Indeed, what I want is: tsc --out A.js A.ts = compile only the A.ts stuff tsc --out B.js B.ts = compile only the B.ts stuff I can do it by removing the "extends" keyword but doing that I'll loose most of the typescript goodness. Can someone telll me if there's a way to do this ?

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• actionscript-3: refactor interface inheritance to get rid of ambiguous reference error

  - by maxmc

  hi! imagine there are two interfaces arranged via composite pattern, one of them has a dispose method among other methods: interface IComponent extends ILeaf { ... function dispose() : void; } interface ILeaf { ... } some implementations have some more things in common (say an id) so there are two more interfaces: interface ICommonLeaf extends ILeaf { function get id() : String; } interface ICommonComponent extends ICommonLeaf, IComponent { } so far so good. but there is another interface which also has a dispose method: interface ISomething { ... function dispose() : void; } and ISomething is inherited by ICommonLeaf: interface ICommonLeaf extends ILeaf, ISomething { function get id() : String; } As soon as the dispose method is invoked on an instance which implements the ICommonComponent interface, the compiler fails with an ambiguous reference error because ISomething has a method called dispose and ILeaf also has a dispose method, both living in different interfaces (IComponent, ISomething) within the inheritace tree of ICommonComponent. I wonder how to deal with the situation if the IComponent, the ILeaf and the ISomething can't change. the composite structure must also work for for the ICommonLeaf & ICommonComponent implementations and the ICommonLeaf & ICommonComponent must conform to the ISomething type. this might be an actionscript-3 specific issue. i haven't tested how other languages (for instance java) handle stuff like this.

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• Porting - Shared Memory x32 & x64 processes

  - by dpb

  A 32 bit host Windows application setups shared memory (using memory mapped file / CreateFileMapping() API), and then other 32 bit client processes use this shared memory to communicate with each other. I am planning to port the host application to 64 bit platform and once it is ready, I intend that both 32 bit and 64 bit client processes should be able to use the shared memory setup by the main 64 bit host application. The original code written for host x32 application uses "size_t" almost everywhere, since this differs from 4 bytes to 8 bytes as we move from x32 to x64, I am looking for replacing it. I intend to replace "size_t" by "unsigned long long", so that its size will be same on 32 bit & 64 bit. Can you please suggest me better alternative? Also, will the use of "unsigned long long" have performance impact on x32 app .. i guess yes? Research Done - Found very useful articles - a) 20 issue in porting from 32 bit to 64 bit (www.viva64.com) b) No way to restrict/change "size_t" on x64 platform to 4 bytes using compiler flags or any hooks/crooks since it is typedef

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• Closures and universal quantification

  - by Apocalisp

  I've been trying to work out how to implement Church-encoded data types in Scala. It seems that it requires rank-n types since you would need a first-class const function of type forAll a. a -> (forAll b. b -> b). However, I was able to encode pairs thusly: import scalaz._ trait Compose[F[_],G[_]] { type Apply = F[G[A]] } trait Closure[F[_],G[_]] { def apply[B](f: F[B]): G[B] } def pair[A,B](a: A, b: B) = new Closure[Compose[PartialApply1Of2[Function1,A]#Apply, PartialApply1Of2[Function1,B]#Apply]#Apply, Identity] { def apply[C](f: A => B => C) = f(a)(b) } For lists, I was able to get encode cons: def cons[A](x: A) = { type T[B] = B => (A => B => B) => B new Closure[T,T] { def apply[B](xs: T[B]) = (b: B) => (f: A => B => B) => f(x)(xs(b)(f)) } } However, the empty list is more problematic and I've not been able to get the Scala compiler to unify the types. Can you define nil, so that, given the definition above, the following compiles? cons(1)(cons(2)(cons(3)(nil)))

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