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  • What's some simple F# code that generates the .tail IL instruction?

    - by kld2010
    I'd like to see the .tail IL instruction, but the simple recursive functions using tail calls that I've been writing are apparently optimized into loops. I'm actually guessing on this, as I'm not entirely sure what a loop looks like in Reflector. I definitely don't see any .tail opcodes though. I have "Generate tail calls" checked in my project's properties. I've also tried both Debug and Release builds in Reflector. The code I used is from Programming F# by Chris Smith, page 190: let factorial x = // Keep track of both x and an accumulator value (acc) let rec tailRecursiveFactorial x acc = if x <= 1 then acc else tailRecursiveFactorial (x - 1) (acc * x) tailRecursiveFactorial x 1 Can anyone suggest some simple F# code which will indeed generate .tail?

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  • How can I login linux using C or C++

    - by jnblue
    I need to programmely switch the current user to another,then the followed code should be executed in the environment(such as path,authority..) of another user. I've find the 'chroot()','setuid()' may be associated with my case, but these functions need the root authority, I don't have root authority, but I have the password of the second user. what should I do? I have tried shell "su - " can switch current user, can this command help me in my C++ code? Don't laugh at me if my question is very stupid, I'm a true freshman on linux. :) Thanks!

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  • Any good idioms for error handling in straight C programs?

    - by Will Hartung
    Getting back in to some C work. Many of my functions look like this: int err = do_something(arg1, arg2, arg3, &result); With the intent the result gets populated by the function, and the return value is the status of the call. The darkside is you get something naive like this: int err = func1(...); if (!err) { err = func2(...); if (!err) { err = func3(...); } } return err; I could macro it I suppose: #define ERR(x) if (!err) { err = (x) } int err = 0; ERR(func1(...)); ERR(func2(...)); ERR(func3(...)); return err; But that only works if I'm chaining function calls, vs doing other work. Obviously Java, C#, C++ have exceptions that work very well for these kinds of things. I'm just curious what other folks do and how other folks do error handling in their C programs nowadays.

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  • Is there a way to read 10000 lines from a file in python?

    - by windsound
    I am relatively new in python, was working on C a lot. Since I was seeing so many new functions in python that I do not know, I was wondering if there is a function that can request 10000 lines from a file in python. Something like this is what I expect if that kind of function exist: lines = get_10000_lines(file_pointer) Did python have a build-in function or is there any module that I can download for this? If not, how do I do this to be easiest way. I need to analyze a huge file so I want to read 10000 lines and analyze per time to save memory. Thanks for helping!

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  • wordpress: previous_post_link() / next_post_link() placeholder

    - by superUntitled
    I am having trouble with the previous_post_link() and next_post_link() functionality. When there is no previous post, the function previous_post_link() does not display a link, likewise for the next_post_link() and the last post. I would like to have a placeholder image so that the design stays consistent. Currently I have images of green arrows pointing left and right, I would like to place an image of a grey arrow if there are no more posts to go back to. Is there a way to use the next_post_link()/previous_post_link() functions but not have the link removed. I also wonder if there is a way for the links to cycle, so that if you come to the most recent post, the next post link would bring you back to the first post.

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  • (g)Vim with version control like Eclipse

    - by Somebody still uses you MS-DOS
    I was an Eclipse user, now I have to use Vim in my machine. I used to "compare" a file I edited with a CVS repository to do merges an commit the files, using a context menu and my mouse. Is this possible in Vim? Opening a vimdiff for a file before commiting, and commit it from vim itself? And how is that supposed to work? I'm supposing I would be editing a file. Then, I want to see the modifications. I run vimdiff in gvim, and a new window (or buffer) is opened. I run the modifications, save what is applicable (using vimdiff commands), and commit running another command. Is this all transparent in vim? Do I have to keep getting out of vim to my terminal, or can all be done inside it? Do I need to use some plugins, or just really simple functions inside my vimrc?

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  • Is pthread_spin_trylock safe inside of sigsegv handler of multithreaded application?

    - by TWMouton
    I am trying to implement a handler that on SIGSEGV will collect some information such as process-id, thread-id and a backtrace and write this information to a file/pipe/socket. The problem lies in that there is the (probably pretty high) possibility that if one thread experienced a SIGSEGV that the others will shortly follow. If two threads happen to make it to the bit of code where they're writing their report out at the same time then they'll interleave their writing (to the same file). I know that I should only be using async-signal-safe functions as detailed in signal(7) I also have seen at least two cases here and video linked in top answer here where others have used pthread_spin_trylock to get around this problem. Is this a safe way to prevent the above problem?

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  • Why does the Win32-API have so many custom types?

    - by sub
    I'm new to the Win32 API and the many new types begin to confuse me. Some functions take 1-2 ints and 3 UINTS as arguments. Why can't they just use ints? What are UINTS? Then, there are those other types: DWORD LPCWSTR LPBOOL Again, I think the "primitive" C types would be enough - why introduce 100 new types? This one was a pain: WCHAR* I had to iterate through it and push_back every character to an std::string as there wasn't another way to convert it to one. Horrible. Why WCHAR? Why reinvent the wheel? They could have just used char* instead, or?

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  • Using template specialization in C++

    - by user550413
    How can I write a function using template specialization that has 2 different input types and an output type: template <class input1, class input2, class output> and return the sum of the 2 numbers (integers/doubles). However, if I get 2 integers I want to return an integer type but for any other combinations of integer and double I'll always return double. I am trying to do that without using directly the '+' operator but having the next functions instead: double add_double_double(double a, double b) {return (a+b);} double add_int_double(int a, double b) {return ((double)(a)+b);} int add_int_int(int a, int b) {return (a+b);}

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  • What open source C/C++ audio compression options are there besides LAME MP3?

    - by Ole Jak
    Are there any C/C++ open source audio encoder besides LAME MP3? It doesn't need to be exactly mp3 format, I need a "compressed digital audio file". I do not want to use Lame because it is too big while no programmer can answer a simple question on it (share simple but easily downloadable and readable project containing only needed 2 simple functions... So I'm tired of searching for help with it.. I need something fresh powerful but more readable than this lib I found (mp3stego) ) "I don't want LAME because I am a fighter with its monopoly" Haha..

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  • Call function by pointer and set parametrs in memory block

    - by Ellesmess Glain
    Hi, I've little problem : I'm solving problem with calling function by pointer and passing to it parameters in continuous memory block. My goal is to have function named e.g CallFunc(void * func,void *params, unsigned int param_length); that I'll send function pointer, pointer to function's parameters and eventually parameters length and this calling function will call passed function with it's parameters. I will like write this in C/C++, but if somebody has idea, how this resolve in other language, that supports DLL generation and exportet functions, it will be fine too. Thanks for answers, Ellesmess P.S. I'm sorry about my English, but I'm Czech, thanks :o)

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  • C++ Boost bind value type {solved}

    - by aaa
    hello. I look in documentation and source code but cannot figure out how to get return value type of boost bind functor. I am trying to accomplish following: 35 template<typename T,size_t N, class F> 36 boost::array<typename F::value_type, N> make_array(T (&input)[N], F unary) { 37 boost::array<typename F::value_type, N> array; 38 std::transform(input, input + N, array.begin(), unary); 39 return array; 40 } where F can be bind functor. the above does not work because functor does not have value_type. for that matter, is there standard interface for unary/binary functor as far as return value. solution: it should be result_type. also equivalent defined are argument_type and first/second_argument_type for binary functions Thanks

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  • More compact way to do this?

    - by Macha
    I have a couple of functions that loop around the surrounding cells of a cell. The grid is contained inside an array. In my code, I have checks to make sure it's not one of the edge cells, as checking an undefined cell causes an error. As such, I have code like this: if(x > 0) { var firstX = x - 1; } else { var firstX = x; } if(x < 199) { var lastX = x + 1; } else { var lastX = x; } if(y > 0) { var firstY = y - 1; } else { var firstY = y; } if(y < 199) { var lastY = y + 1; } else { var lastY = y; } A lot of lines of code to do very little. Is there a more elegant way to do this?

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  • How to keep the first result of a function from Prolog?

    - by zuhakasa
    I need to write a customized function that will be called many times by other fixed functions. In this function, at the first called time, it will return the total number of lines of a file. The second called time of this function, forward, will return the number of lines in small sections of this file. My question is how I keep the first returned result(total number of lines of a file) and use it for the next called times of my function. I need to write or declare any thing only in this function(not in the caller). Something like this: myFunction(Input, MyResult, FirstResult) :- calculateInputFunction(Input, Result), !, MyResult is Result, ... . The problem is, every time myFunction is called, it receives different Input and returns different MyResult. But I would like to keep the first MyResult to use for next called times of myFunction. How can I do that? Thanks very much for your answer in advance.

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  • C++ Static Array Initialization - Memory Issue

    - by donalmg
    Hi, I have a header file which contains a member variable declaration of a static char array: class ABC { public: static char newArray[4]; // other variables / functions private: void setArray(int i, char * ptr); } In the CPP file, I have the array initialized to NULL: char ABC::newArray[4] = {0}; In the ABC constructor, I need to overwrite this value with a value constructed at runtime, such as the encoding of an integer: ABC::ABC() { int i; //some int value defined at runtime memset(newArray, 0, 4); // not sure if this is necessary setArray(i,newArray); } ... void setArray(int i, char * value) { // encoding i to set value[0] ... value [3] } When I return from this function, and print the modified newArray value, it prints out many more characters than the 4 specified in the array declaration. Any ideas why this is the case. I just want to set the char array to 4 characters and nothing further. Thanks...

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  • Are sessions modifiable by the client/user?

    - by Sev
    In my PHP Web-App I use sessions to store the user's data. For exmaple, if a user logs in, then an instance of the User class is generated and stored in a Session. I have access levels associated with each user to determine their privileges. Store the user in a session by: $_SESSION['currentUser'] = new User($_POST['username']); For example: if($_SESSION['currentUser'] -> getAccessLevel() == 1) { //allow administration functions } where getAccessLevel() is simply a get method in the User class that returns the _accesslevel member variable. Is this secure? Or can the client somehow modify their access level through session manipulation of some sort?

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  • JQuery create new select option

    - by nav
    Hi I have the below functions in regular javascript creating select options. Is there a way I can do this with JQuery without having to use the form object? function populate(form) { form.options.length = 0; form.options[0] = new Option("Select a city / town in Sweden",""); form.options[1] = new Option("Melbourne","Melbourne"); } Below is how I call the function above: populate(document.form.county); //county is the id of the dropdownlist to populate. Many Thanks,

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  • including a string as a parameter to a function in a header file? c++

    - by Nara
    hello everyone, total newbie is here :) i have this header file, zeeheader.h, and i wrote some classes in it, i'm having problems giving a string as a parameter to one of the functions: class DeliTest { public: void DeliCheck(Stack*,string); void ComCheck (unsigned,string); bool EofCheck (unsigned,string); }; as i was implementinng it in the cpp file, i added #include to it, it seemed to be working, for example : as i was writing the "data." i got the "length()" appear by the intellisense, so i thought that it was working, but it wasn't. i got errors like: syntax error : identifier 'string' overloaded member function not found in 'DeliTest' this is one of the fucntions in the cpp file: bool DeliTest::EofCheck(unsigned i, string data) { if (i == data.length()-1) return 1; return 0; } am i supposed to be adding something to the header file??

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  • How to import .class file in a .java file?

    - by Namratha
    Hi, What i need to do is as follows: I have a bigloo scheme program (*.scm), then using the bigloo frameworks jvm a class file is generated. I want to use this .class file from a .java file. That is, i need to import this(.class) file as i want to use some functions defined in the scheme file which is now a .class file. How do i do it in Eclipse? i have created two packages one for java and one for the .class file. Then i import the package containing the .class file. But i am not able to use the function in the .class file in the .java file. Are there any settings to be done? Please let me know how this can be done.

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  • [Python] Help me : how i can deal with web page !

    - by Str1k3r
    hello every one... am looking for modules or functions let's me joins in id web !!!! i mean like i told python go to hotmail.com then go to signup ! how i can do that i mean how i can tell python go to hotmail.com then find some thing called signup in source page then i tell him join to him ....etc i hope you understand my idea ! ** am thinking on urllib2 .. maybe it's can do that? am just new in python

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  • between syntax, are there any equal function

    - by gcc
    /* char **mainp=malloc(sizeof(char *)*2); mainp[0]=malloc(sizeof(char)*300); mainp[1]=malloc(sizeof(char )*300); */ *I have some input about propositional calculus *After calculating some math funtion-removing paranthesis-changing"&" with ","-replacing "|" with"," I have >> (1) P,-Q,Q,-R is stored in mainp[0] R,A,P,B,F is stored in mainp[1] *My question is: Between comma , I have want to compare two pointer array. If there is any equal two or more functions(Q,-R is function representation) ,function which you will show me how to write must return int. According to example (1),function will return 1 (I expect like that) /*I have som thought://which function should I have use:*/ in for loop if( strspn(mainp[0][i])==1 ) increment d; continue; or in for loop srtcmp(mainp[0][i],mainp[1]);

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  • PotgreSQL 2D array to rows

    - by PostGreSQL newbie
    Hello, I am new to PostgreSQL array's. I am trying to a write a procedure to convert array-into-rows, and wanted following output: alphabet | number ---------+---------- A | 10 B | 10 C | 6 D | 9 E | 3 from following: id | alphabet_series -------+-------------------------------------------------------------------------------------------------- 1 | {{A,10},{B,10},{C,6},{D,9},{E,3},{F,9},{I,10},{J,17},{K,16},{L,17},{M,20},{N,13},{O,19}} I have searched for array-to-rows functions, but they all seems to accept 1-d array. but in this case, it is 2-d array. Any pointers will be appreciated. Many thanks.

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  • Method to register method to be called when event is raised

    - by zaidwaqi
    I have a Panel which contains 20 PictureBox controls. If a user clicks on any of the controls, I want a method within the Panel to be called. How do I do this? public class MyPanel : Panel { public MyPanel() { for(int i = 0; i < 20; i++) { Controls.Add(new PictureBox()); } } // DOESN'T WORK. // function to register functions to be called if the pictureboxes are clicked. public void RegisterFunction( <function pointer> func ) { foreach ( Control c in Controls ) { c.Click += new EventHandler( func ); } } } How do I implement RegisterFunction()? Also, if there are cool C# features that can make the code more elegant, please share.

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  • Boost singleton trouble

    - by Ockonal
    Hi guys, I have some class which uses boost singleton. It calls some function from own c++ library. This library is written in make file as dependence. Now I have another singleton class and it should call first singleton class. After this code I got linkers error about undefined references for functions which are used in first singleton. When I remove calling first singleton class from second the errors remove. Maybe there is something wrong?

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  • Singly-Linked Lists insert_back and isIncreasing

    - by rezivor
    I just finished writing a program that I can add, remove or print objects to a list, but I am having difficulty implementing two more functions that is insert_back, which inserts a value to the end of a list. Also,I have to modify the representation of a List and alter whatever methods are necessary to make insert_back run in constant time: O(1). This new operation should have the signature: void List::insert_back( const Object& data ); Also, isIncreasing, For example, for a list containing head-() (11) (8) (15) (3), isIncreasing() should return false. However, it would return true when working on a list containing head- () (7) (9) (15). This new operation should have the signature: bool List::isIncreasing() const; Thank you

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