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  • Inline function v. Macro in C -- What's the Overhead (Memory/Speed)?

    - by Jason R. Mick
    I searched Stack Overflow for the pros/cons of function-like macros v. inline functions. I found the following discussion: Pros and Cons of Different macro function / inline methods in C ...but it didn't answer my primary burning question. Namely, what is the overhead in c of using a macro function (with variables, possibly other function calls) v. an inline function, in terms of memory usage and execution speed? Are there any compiler-dependent differences in overhead? I have both icc and gcc at my disposal. My code snippet I'm modularizing is: double AttractiveTerm = pow(SigmaSquared/RadialDistanceSquared,3); double RepulsiveTerm = AttractiveTerm * AttractiveTerm; EnergyContribution += 4 * Epsilon * (RepulsiveTerm - AttractiveTerm); My reason for turning it into an inline function/macro is so I can drop it into a c file and then conditionally compile other similar, but slightly different functions/macros. e.g.: double AttractiveTerm = pow(SigmaSquared/RadialDistanceSquared,3); double RepulsiveTerm = pow(SigmaSquared/RadialDistanceSquared,9); EnergyContribution += 4 * Epsilon * (RepulsiveTerm - AttractiveTerm); (note the difference in the second line...) This function is a central one to my code and gets called thousands of times per step in my program and my program performs millions of steps. Thus I want to have the LEAST overhead possible, hence why I'm wasting time worrying about the overhead of inlining v. transforming the code into a macro. Based on the prior discussion I already realize other pros/cons (type independence and resulting errors from that) of macros... but what I want to know most, and don't currently know is the PERFORMANCE. I know some of you C veterans will have some great insight for me!!

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  • cygwin sed substitution against commands in history

    - by Ira
    I couldn't find an answer for this exact problem, so I'll ask it. I'm working in Cygwin and want to reference previous commands using !n notation, e.g., if command 5 was which ls, then !5 runs the same command. The problem is when trying to do substitution, so running: !5:s/which \([a-z]\)/\1/ should just run ls, or whatever the argument was for which for command number 5. I've tried several ways of doing this kind of substitution and get the same error: bash: :s/which \([a-z]*\)/\1/: substitution failed

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  • Designing a chain of states

    - by devoured elysium
    I want to model a kind of FSM(Finite State Machine). I have a sequence of states (let's say, from StateA to StateZ). This sequence is called a Chain and is implemented internally as a List. I will add states by the order I want them to run. My purpose is to be able to make a sequence of actions in my computer (for example, mouse clicks). (I know this has been done a zillion times). So a state is defined as a: boolean Precondition() <- Checks to see if for this state, some condition is true. For example, if I want to click in the Record button of a program, in this method I would check if the program's process is running or not. If it is, go to the next state in the chain list, otherwise, go to what was defined as the fail state (generally is the first state of them all). IState GetNextState() <- Returns the next state to evaluate. If Precondition() was sucessful, it should yield the next state in the chain otherwise it should yield the fail state. Run() Simply checks the Precondition() and sets the internal data so GetNextState() works as expected. So, a naive approach to this would be something like this: Chain chain = new Chain(); //chain.AddState(new State(Precondition, FailState, NextState) <- Method structure chain.AddState(new State(new WinampIsOpenCondition(), null, new <problem here, I want to referr to a state that still wasn't defined!>); The big problem is that I want to make a reference to a State that at this point still wasn't defined. I could circumvent the problem by using strings when refrering to states and using an internal hashtable, but isn't there a clearer alternative? I could just pass only the pre-condition and failure states in the constructor, having the chain just before execution put in each state the correct next state in a public property but that seems kind of awkward.

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  • How to wrap Ruby strings in HTML tags

    - by Jason H.
    Hi all: I'm looking for help on two things. 1) I'm looking for a way for Ruby to wrap strings in HTML. I have a program I'm writing that generates a Hash of word frequencies for a text file and I want to take the results and place it into an HTML file rather than print to STDOUT. I'm thinking each string needs to be wrapped in an HTML paragraph tag using readlines() or something, but I can't quite figure it out. Then, once I've wrapped the strings in HTML 2) I want to write to an empty HTML file. Right now my program looks like: filename = File.new(ARGV[0]).read().downcase().scan(/[\w']+/) frequency = Hash.new(0) words.each { |word| frequency[word] +=1 } frequency.sort_by { |x,y| y }.reverse().each{ |w,f| puts "#{f}, #{w}" } So if we ran a text file through this and received: 35, the 27, of 20, to 16, in # . . . I'd want to export to an HTML file that wraps the lines like: <p>35, the</p> <p>27, of</p> <p>20, to</p> <p>16, in</p> # . . . Thanks for any tips in advance!

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  • Decimal To Octal Converter, last digit issue

    - by Srishan Supertramp
    I tried making a C program to convert a user entered decimal number to octal. I wrote the C code with my own logic without any research of how other users try to do it. It works fine for the number 601 and some other numbers but for most numbers it returns the octal equivalent with the last digit being 1 less than it should be. For 75 it returns 112 instead of 113. I realize using printf with %o gets the job done but it's kind of defeating the purpose of learning to program. Here's my code: #include <stdio.h> #include <math.h> /* converting decimal to octal */ int main() { int n,x,y,p,s; printf("Enter a decimal number "); scanf("%d",&x); s=0;p=0; while (x!=0) { y=x%8; s=s+y*pow(10,p); x=(x-y)/8; p=p+1; } printf("the octal equivalent is: %d\n",s); getch(); return 0; }

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  • Variable modification in a child process

    - by teaLeef
    I am working on Bryant and O'Hallaron's Computer Systems, A Programmer's Perspective. Exercise 8.16 asks for the output of a program like (I changed it because they use a header file you can download on their website): #include <stdio.h> #include <stdlib.h> #include <sys/types.h> #include <sys/wait.h> #include <errno.h> #include <unistd.h> #include <string.h> int counter = 1; int main() { if (fork() == 0){ counter--; exit(0); } else{ Wait(NULL); printf("counter = %d\n", ++counter); } exit(0); } I answered "counter = 1" because the parent process waits for its children to terminate and then increments counter. But the child first decrements it. However, when I tested the program, I found that the correct answer was "counter = 2". Is the variable "counter" different in the child and in the parent process? If not, then why is the answer 2?

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  • C# CodeDom - making project's forms accessible for scripts.

    - by michal
    Hi, I'm learning CodeDom scripting, I started with http://www.c-sharpcorner.com/uploadfile/mgold/codedomcalculator08082005003253am/codedomcalculator.aspx Now I'd like to allow script modify the project's form (for learning purposes only). I suppose I need to create new field for a class I'm generating which refers "this". However I have no idea how can I set a reference for script-accessible object ... ? Or can I directly publish some class member (like "this" or "button1") to a CodeDom script structure?

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  • How do you programmatically move the caret of a Flex TextArea to the end?

    - by Akinwale
    I'm trying to move the caret in a Flex TextArea to the end after appending some text from my code. I've looked through the reference documentation for TextArea and its underlying TextField but it appears there is no method provided to handle this. One approach I've tried is to set focus to the text area and dispatch a KeyUp KeyboardEvent with the event's key code set to the "End" key, but this doesn't work. Any ideas on how to do this? Thanks.

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  • Is there a jQuery widget equal to DOJO's TitlePane?

    - by Bill Caswell
    I like the visual behavior of the DOJO TitlePane widget, but it has too much other bunk for my purpose. http://dojotoolkit.org/reference-guide/dijit/TitlePane.html#dijit-titlepane Is anyone aware of a jQuery widget that provides the same ability to expose and hide content in a stacked manner with the little flippy-arrow, pane highlighting on mouse over, etc? An accordion does not accomplish my goal being able to have multiple panes open at the same time. Thanks in advance.

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  • Django url rewrites and passing a parameter from Javascript

    - by William T Wild
    As a bit of a followup question to my previous , I need to pass a parameter to a view. This parameter is not known until the JS executes. In my URLConf: url(r'^person/device/program/oneday/(?P<meter_id>\d+)/(?P<day_of_the_week>\w+)/$', therm_control.Get_One_Day_Of_Current_Thermostat_Schedule.as_view(), name="one-day-url"), I can pass it this URL and it works great! ( thanks to you guys). http://127.0.0.1:8000/personview/person/device/program/oneday/149778/Monday/ In My template I have this: var one_day_url = "{% url personview:one-day-url meter_id=meter_id day_of_the_week='Monday' %}"; In my javascript: $.ajax({ type: 'GET', url: one_day_url , dataType: "json", timeout: 30000, beforeSend: beforeSendCallback, success: successCallback, error: errorCallback, complete: completeCallback }); When this triggers it works fine except I dont necessarily want Monday all the time. If I change the javascript to this: var one_day_url = "{% url personview:one-day-url meter_id=meter_id %}"; and then $.ajax({ type: 'GET', url: one_day_url + '/Monday/', dataType: "json", timeout: 30000, beforeSend: beforeSendCallback, success: successCallback, error: errorCallback, complete: completeCallback }); I get the Caught NoReverseMatch while rendering error. I assume because the URLconf still wants to rewrite to include the ?P\w+) . I seems like if I change the URL conf that breaks the abailty to find the view , and if I do what I do above it gives me the NoREverseMatch error. Any guidance would be appreciated.

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  • Prototyping Qt/C++ in Python

    - by tstenner
    I want to write a C++ application with Qt, but build a prototype first using Python and then gradually replace the Python code with C++. Is this the right approach, and what tools (bindings, binding generators, IDE) should I use? Ideally, everything should be available in the Ubuntu repositories so I wouldn't have to worry about incompatible or old versions and have everything set up with a simple aptitude install. Is there any comprehensive documentation about this process or do I have to learn every single component, and if yes, which ones? Right now I have multiple choices to make: Qt Creator, because of the nice auto completion and Qt integration. Eclipse, as it offers support for both C++ and Python. Eric (haven't used it yet) Vim PySide as it's working with CMake and Boost.Python, so theoretically it will make replacing python code easier. PyQt as it's more widely used (more support) and is available as a Debian package. Edit: As I will have to deploy the program to various computers, the C++-solution would require 1-5 files (the program and some library files if I'm linking it statically), using Python I'd have to build PyQt/PySide/SIP/whatever on every platform and explain how to install Python and everything else.

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  • c++ figuring out memory layout of members programatically

    - by anon
    Suppose in one program, I'm given: class Foo { int x; double y; char z; }; class Bar { Foo f1; int t; Foo f2; }; int main() { Bar b; bar.f1.z = 'h'; bar.f2.z = 'w'; ... some crap setting value of b; FILE *f = fopen("dump", "wb"); // c-style file fwrite(&b, sizeof(Bar), 1, f); } Suppose in another program, I have: int main() { File *f = fopen("dump", "rb"); std::string Foo = "int x; double y; char z;"; std::string Bar = "Foo f1; int t; Foo f2;"; // now, given this is it possible to read out // the value of bar.f1.z and bar.f2.z set earlier? } WHat I'm asking is: given I have the types of a class, can I figure out how C++ lays it out?

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  • [FIXED] Scan file contents into an array of a structure.

    - by ZaZu
    Hello, I have a structure in my program that contains a particular array. I want to scan a random file with numbers and put the contents into that array. This is my code : ( NOTE : This is a sample from a bigger program, so I need the structure and arrays as declared ) The contents of the file are basically : 5 4 3 2 5 3 4 2 #include<stdio.h> #define first 500 #define sec 500 struct trial{ int f; int r; float what[first][sec]; }; int trialtest(trial *test); main(){ trial test; trialtest(&test); } int trialtest(trial *test){ int z,x,i; FILE *fin; fin=fopen("randomfile.txt","r"); for(i=0;i<5;i++){ fscanf(fin,"%5.2f\t",(*test).what[z][x]); } fclose(fin); return 0; } But the problem is, whenever this I run this code, I get this error : (25) : warning 508 - Data of type 'double' supplied where a pointer is required I tried adding do{ for(i=0;i<5;i++){ q=fscanf(fin,"%5.2f\t",(*test).what[z][x]); } }while(q!=EOF); But that didnt work either, it gives the same error. Does anyone have a solution to this problem ?

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  • After calling a COM-dll component, C# exceptions are not caught by the debugger

    - by shlomil
    I'm using a COM dll provided to me by 3rd-party software company (I don't have the source code). I do know for sure they used Java to implement it because their objects contain property names like 'JvmVersion'. After I instantiated an object introduced by the provided COM dll, all exceptions in my C# program cannot be caught by the VS debugger and every time an exception occurs I get the default Windows Debugger Selection dialog (And that's while executing my program in debug mode under a full VisualStudio debugging environment). To illustrate: throw new Exception("exception 1"); m_moo = new moo(); // Component taken from the COM-dll throw new Exception("exception 2"); Exception 1 will be caught by VS and show the "yellow exception window". Exception 2 will open a dialog titled "Visual Studio Just-In-Time Debugger" containing the text "An unhandled win32 exception occurred in myfile.vshost.exe[1348]." followed by a list of the existing VS instances on my system to select from. I guess the instantiation of "moo" object overrides C#'s exception handler or something like that. Am I correct and is there a way to preserve C#'s exception handler?

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  • When is a try catch not a try catch?

    - by Dearmash
    I have a fun issue where during application shutdown, try / catch blocks are being seemingly ignored in the stack. I don't have a working test project (yet due to deadline, otherwise I'd totally try to repro this), but consider the following code snippet. public static string RunAndPossiblyThrow(int index, bool doThrow) { try { return Run(index); } catch(ApplicationException e) { if(doThrow) throw; } return ""; } public static string Run(int index) { if(_store.Contains(index)) return _store[index]; throw new ApplicationException("index not found"); } public static string RunAndIgnoreThrow(int index) { try { return Run(index); } catch(ApplicationException e) { } return ""; } During runtime this pattern works famously. We get legacy support for code that relies on exceptions for program control (bad) and we get to move forward and slowly remove exceptions used for program control. However, when shutting down our UI, we see an exception thrown from "Run" even though "doThrow" is false for ALL current uses of "RunAndPossiblyThrow". I've even gone so far as to verify this by modifying code to look like "RunAndIgnoreThrow" and I'll still get a crash post UI shutdown. Mr. Eric Lippert, I read your blog daily, I'd sure love to hear it's some known bug and I'm not going crazy. EDIT This is multi-threaded, and I've verified all objects are not modified while being accessed

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  • deserializing multiple types from a stream

    - by clanier9
    I have a card game program, and so far, the chat works great back and forth over the TCPClient streams between host and client. I want to make it do this with serializing and deserializing so that I can also pass cards between host and client. I tried to create a separate TCPClient stream for the passing of cards but it didn't work and figured it may be easier to keep one TCPClient stream that gets the text messages as well as cards. So I created a class, called cereal, which has the properties for the cards that will help me rebuild the card from an embedded database of cards on the other end. Is there a way to make my program figure out whether a card has been put in the stream or if it's just text in the stream so I can properly deserialize it to a string or to a cereal? Or should I add a string property to my cereal class and when that property is filled in after deserializing to the cereal, i'll know it's just text (if that field is empty after deserializing i'll know it's a card)? I'm thinking a try catch, where it tries to deserialize to a string, and if it fails it will catch and cast as a cereal. Or am I just way off base with this and should choose another route? I'm using visual studio 2011, am using a binaryformatter, and am new to serializing/deserializing.

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  • Proper QUuid usage in Qt ? (7-Zip DLL usage problems (QLibrary, QUuid GUID conversion, interfaces))

    - by whipsnap
    Hi, I'm trying to write a program that would use 7-Zip DLL for reading files from inside archive files (7z, zip etc). Here's where I'm so far: #include QtCore/QCoreApplication #include QLibrary #include QUuid #include iostream using namespace std; #include "7z910/CPP/7zip/Archive/IArchive.h" #include "7z910/CPP/7zip/IStream.h" #include "MyCom.h" // {23170F69-40C1-278A-1000-000110070000} QUuid CLSID_CFormat7z(0x23170F69, 0x40C1, 0x278A, 0x10, 0x00, 0x00, 0x01, 0x10, 0x07, 0x00, 0x00); typedef int (*CreateObjectFunc)( const GUID *clsID, const GUID *interfaceID, void **outObject); void readFileInArchive() { QLibrary myLib("7z.dll"); CreateObjectFunc myFunction = (CreateObjectFunc)myLib.resolve("CreateObject"); if (myFunction == 0) { cout outArchive; myFunction(&CLSID_CFormat7z, &IID_IOutArchive, (void **)&outArchive); } int main(int argc, char *argv[]) { QCoreApplication a(argc, argv); readFileInArchive(); return a.exec(); } Trying to build that in Qt Creator will lead to following error: cannot convert 'QUuid*' to 'const GUID*' in argument passing How should QUuid be correctly used in this context? Also, being a C++ and Qt newbie I haven't yet quite grasped templates or interfaces, so overall I'm having trouble getting through these first steps. If someone could give tips or even example code on how for example an image file could be extracted from ZIP file (to be shown in Qt GUI later on*), I would highly appreciate that. My main goal at the moment is to write a program with GUI for selecting archive files containing image files (PNG, JPG etc) and displaying those files one at a time in the GUI. A Qt based CDisplayEx in short.

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  • Apple 360 example

    - by frankB
    maybe all of you saw the Apple html5 shocases...thing is they didnt put online anything downloadable, am I right? someone found a 360 example that we can download and use as is instead of going trought the Safari Reference book...? thanks

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  • C#, add references manually

    - by A B
    Is there anyway I can make the process of adding references to C# projects less painfull? Every time I create a new C# class library project. I have to use the Add Reference dialog for 5 times at least.

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