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  • Reading long lines from text file

    - by sonofdelphi
    I am using the following code for reading lines from a text-file. What is the best method for handling the case where the line is greater than the limit SIZE_MAX_LINE? void TextFileReader::read(string inFilename) { ifstream xInFile(inFilename.c_str()); if(!xInFile){ return; } char acLine[SIZE_MAX_LINE + 1]; while(xInFile){ xInFile.getline(acLine, SIZE_MAX_LINE); if(xInFile){ m_sStream.append(acLine); //Appending read line to string } } xInFile.close(); }

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  • array loop not working correctly? c++

    - by igor
    Trying to count how many elements within the array are not equal to 0, is something set up wrong? I'd like to check all values in the array (it's a sudoku board) and then when all elements are "full" I need to return true. Is something off? bool boardFull(const Square board[BOARD_SIZE][BOARD_SIZE]) { int totalCount=0; for (int index1 = 0; index1 < BOARD_SIZE; index1++) for (int index2 = 0; index2 < BOARD_SIZE; index2++){ if(board[index1][index2].number!=0) totalCount++; } if(totalCount=81) return true; else return false;

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  • Strange macro declaration in C

    - by Andrey Atapin
    Exploring libusb-1.0.9 source code, I have found such line (./os/poll_windows.c:78): #define CHECK_INIT_POLLING do {if(!is_polling_set) init_polling();} while(0) As for me this is the same like: #define CHECK_INIT_POLLING if(!is_polling_set) init_polling(); Is there any reason to loop that expression? UPDATE: I couldn't still realize what'd be wrong after the answers, and the following example helped: #include <stdio.h> #define TEST if(test) foo(); #define TEST_DO do { if(test) foo(); } while(0) int test = 1; void foo() { printf("%s", "Foo called"); } int main(int argc, char** argv) { if(argc > 1) TEST_DO; /* LINE 12 */ else printf("%s", "skipping..."); return 0; } If you put TEST at line 12, a compiler will give an error "error: ‘else’ without a previous ‘if’". Hope, this will help someone.

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  • The glutKeyboardFunc does not react to key presses immediately

    - by Nibirue
    I have a function glutKeyboardFunc(keyboard), where keyboard has: void keyboard(unsigned char key, int x, int y){ float alpha = 1.0; switch(key){ case 'c': glClearColor(1,0,0,alpha); printf("success"); break; } } This is a summary of the function; it works properly, but only once some other action has occurred. For instance, the printf statement reports success immediately on keystroke 'c', but the background color does not become active until I click somewhere else on the canvas. I want all keystrokes to have an immediate effect.

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  • Event handling C# / Registering a callback

    - by Jeff Dahmer
    Events can only return void and recieve object sender/eventargs right? If so then craptastic.... how can I pass a function pointer to another obj, like: public bool ACallBackFunc(int n) { return n > 0; } public void RegisterCallback(Something s) { s.GiveCallBack(this.ACallBackFunc); } Something::GiveCallBack(Action? funcPtr) I tried using Action, but I need it to return some value and Actions can only return void. Also, we do not know what kind of a callback we will be recieving; it could return anything and have any params! Reflection will have to be used somehow I reckon.

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  • C input loop for shell

    - by AustinM
    So I'm working on creating a very simple C program that just preforms shell commands. This is what I have so far: #include <stdio.h> int main() { char input[30]; fputs("$ ", stdout); fflush(stdout); fgets(input, sizeof input, stdin); system(input); } It works, but only for one command. For example if I compile and type ./cmd I get the $ prompt. If I type ls I get what I'm supposed to get. But then it exits and goes back to the regular system shell. How can I make it so after the user types a command it goes back to the "$" input.

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  • std::out_of_range error?

    - by vette982
    I'm dealing with a file with a linked list of lines with each node looking like this: struct TextLine{ //The actual text string text; //The line number of the document int line_num; //A pointer to the next line TextLine * next; }; and I'm writing a function that adds spaces at the beginning of the lines found in the variable text, by calling functions like linelist_ptr->text.insert(0,1,'\t'); The program compiles, but when I run it I get this error: terminate called after throwing an instance of 'std::out_of_range' what(): basic_string::at Aborted Any ideas?

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  • memset on array of structures in C++

    - by garry
    I have another memset question. It appears as if the code I am editing may have some issues (or it's not done the same way in different files) A::LRM las[9]; //A and LRM are both structures with BOOLS and INTS memset(&las, 0, sizeof(las)); typedef Sec SecArray[16]; SecArray rad_array; memset(rad_array, 0, sizeof(SecArray)); The second example appears to be correct because rad_array is the same as the first position in the array. Then the sizeof(SecArray)) would make sense. The first one doesn't seem correct to me. All structs are just BOOLs and INTS nothing dynamic in them. My understanding from my other post about memset was that it followed this format. memset("pointer to object", "what to set it to", "size of object") Can anyone tell me what exactly is going on here if I am incorrect with my theory.

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  • SQL tables using VARCHAR with UTF8 (with respect to multi byte character length)

    - by Elius
    Like in Oracle VARCHAR( 60 CHAR ) I would like to specify a varchar field with variable length depending on the inserted characters. for example: create table X (text varchar(3)) insert into X (text) VALUES ('äöü') Should be possible (with UTF8 as the default charset of the database). On DB2 I got this Error: DB2 SQL Error: SQLCODE=-302, SQLSTATE=22001 (Character data, right truncation occurred; for example, an update or insert value is a string that is too long for the column, or a datetime value cannot be assigned to a host variable, because it is too small.) I'm looking for solutions for DB2, MsSql, MySql, Hypersonic.

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  • Why do virtual memory addresses for linux binaries start at 0x8048000?

    - by muteW
    Disassembling an ELF binary on a Ubuntu x86 system I couldn't help but notice that the code(.text) section starts from the virtual address 0x8048000 and all lower memory addresses seem to be unused. This seems to be rather wasteful and all Google turns up is either folklore involving STACK_TOP or protection against null-pointer dereferences. The latter case looks like it can be fixed by using a single page instead of leaving a 128MB gap. So my question is this - is there a definitive answer to why the layout has been fixed to these values or is it just an arbitrary choice?

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  • crc24 from c to python

    - by biiiiiaw
    can someone please translate this code to python? i have tried and tried again, but have not managed it: #define CRC24_INIT 0xB704CEL #define CRC24_POLY 0x1864CFBL typedef long crc24; crc24 crc_octets(unsigned char *octets, size_t len) { crc24 crc = CRC24_INIT; int i; while (len--) { crc ^= (*octets++) << 16; for (i = 0; i < 8; i++) { crc <<= 1; if (crc & 0x1000000) crc ^= CRC24_POLY; } } return crc & 0xFFFFFFL; } i have the rotate left function (ROL24(value,bits_to_rotate_by)), which i know works since i got it from a source code of a reputable programmer, but i dont get the * and ++ on octet. i only sort of understand how ++ works in c++, and i dont know what * is at all

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  • boost scoped_lock mutex crashes

    - by JahSumbar
    hello, I have protected a std::queue's access functions, push, pop, size, with boost::mutexes and boost::mutex::scoped_lock in these functions from time to time it crashes in a scoped lock the call stack is this: 0 0x0040f005 boost::detail::win32::interlocked_bit_test_and_set include/boost/thread/win32/thread_primitives.hpp 361 1 0x0040e879 boost::detail::basic_timed_mutex::timed_lock include/boost/thread/win32/basic_timed_mutex.hpp 68 2 0x0040e9d3 boost::detail::basic_timed_mutex::lock include/boost/thread/win32/basic_timed_mutex.hpp 64 3 0x0040b96b boost::unique_lock<boost::mutex>::lock include/boost/thread/locks.hpp 349 4 0x0040b998 unique_lock include/boost/thread/locks.hpp 227 5 0x00403837 MyClass::inboxSize - this is my inboxSize function that uses this code: MyClass::inboxSize () { boost::mutex::scoped_lock scoped_lock(m_inboxMutex); return m_inbox.size(); } and the mutex is declared like this: boost::mutex m_inboxMutex; it crashes at the last pasted line in this function: inline bool interlocked_bit_test_and_set(long* x,long bit) { long const value=1<<bit; long old=*x; and x has this value: 0xababac17 Thanks for the help

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  • How to get "printer ready bytes" from a source in c#?

    - by luis_villase
    Hey everyone! I'm in a bit of trouble here, hoping you can help a fellow programmer out. I have an application that receives a pointer to raw bytes (plus length and stuff) and sends said raw data to a printer. This is important, I have no choice but to use this method to get any printing done. If I send a raw string, it will print with no problem. However, I need to be able to print formatted text, images, etc. So the thing is... I would like to be able to get printer ready bytes from a given source (maybe a pdf, or html, does not matter as long as it contains formatted text and/or images). It would be like "splitting" the print command like so: a) Open file and read data b) Load printer data into memory c) Send bytes to printer Obviously, I've got a) and c) covered, it's b) the one that's breaking my head. Any thoughts? Thanks in advance for your help.

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  • Oracle spatial search within distance

    - by KA_lin
    I have the following table Cities: ID(int),City(char),latitude(float),longitude(float). Now based on a user`s longitude(ex:44.8) and latitude(ex:46.3) I want to search for all the cities near him within 100 miles/KM. I have found some examples but don`t know how to adapt them to my case select * from GEO.Cities a where SDO_WITHIN_DISTANCE([I don`t know], MDSYS.SDO_GEOMETRY(2001, 8307, MDSYS.SDO_POINT_TYPE(44.8,46.3, NULL) ,NULL, NULL), 'distance = 1000') = 'TRUE'; Any help would be appreciated. P.S: If it is possible to have the distance and to be sorted P.P.S: I want to do it in this way due to performance issues, I have done this in this way http://www.scribd.com/doc/2569355/Geo-Distance-Search-with-MySQL but it takes too long...

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  • Extract data from uint8 to double

    - by HADJ AMOR HASSEN
    I have a C function receiving a uint8 pointer with another parameter which is its size (number of bytes). I want to extract double data from this buffer. Here is my code: Write(uint8* data, uint8 size) /* data and size are given by a callback to my function)*/ { double d; for (i = 0; i < size; i++) { d = ((double*)&data)[i]; printf(" d = %d\n"); } } The problem is that I am not receiving what I am sending within an external hardware. I guess that my cast is wrong. I tried other methods but without any good result. I am still not able to get what I send.

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  • DataSet binding problem

    - by Shaine
    I've got in-memory dataset with some table defined and I populate this table in a following way: for(...) ds.Fields.AddFieldsRow(++j, 0, heading, "Char", "", "", "Input", 0, "","",""); On the GUI I've got DataGridView bound to that table inside TabControl (bound through BindingSource). Very strange thing is happening: if I open tab pane with this grid and populate table with some data then I see changes in grid. On the other side if I'm at other tab, populate table, and then switch to tab with grid I've got following exception: "DataMember property 'Fields' cannot be found on the DataSource". In similar way I've got 2 tab panes with grid in each that are bound to the same datatable using different datasources and I open one of them, populate, see the changes, then switch to second tab and get crash. What am I missing?

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  • Is call to function object inlined?

    - by dehmann
    In the following code, Foo::add calls a function via a function object: struct Plus { inline int operator()(int x, int y) const { return x + y; } }; template<class Fct> struct Foo { Fct fct; Foo(Fct f) : fct(f) {} inline int add(int x, int y) { return fct(x,y); // same efficiency adding directly? } }; Is this the same efficiency as calling x+y directly in Foo::add? In other words, does the compiler typically directly replace fct(x,y) with the actual call, inlining the code, when compiling with optimizations enabled?

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  • user buffer after doing 'write' to file opened with O_DIRECT

    - by user1868481
    I'm using the O_DIRECT flag to write to the disk directly from the user buffer. But as far as I understand, Linux doesn't guarantee that after this call, the data is written. It just writes directly from the user buffer to the physical device using DMA or anything else... Therefore, I don't understand if I can write to the user buffer after the call to 'write' function. I'm sure that example code will help to understand my question: char *user_buff = malloc(...); /* assume it is aligned as needed */ fd = open(..., O_DIRECT); write(fd, ...) memset(user_buff, 0, ...) Is the last line (memset) legal? Is writing to the user buffer valid that is maybe used by DMA to transfer data to the device?

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  • can we write this in C++ switch ?

    - by jellly
    #include <iostream> using namespace std; int main(){ char i; cin >>i; switch (i){ case ('e'||'i'||'o'||'u'||'a'): cout<<"Vowel"; break; case ('+'||'-'||'/'||'*'||'%'): cout<<"Op"; break; } return 0; } if not than how can we use comparison or logical operators in switch ? & why cant we declare and initialize variable in single case without using scope ?

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  • Where do you hang your semantic information, html?

    - by bobobobo
    Well, I keep putting semantic information about what an element means for the page logically in the class attribute <li class="phone-number">555-5555</li> It seems to work for this dual purpose of hanging semantic information and a pointer to how to style it. I'm not sure if this is the best idea, I'm trying to see if others have other ways of doing it. I also started to use a hidden input: <li>555-5555 <input class="semantics" type="hidden" value="phone-number" /></li> inside an element, so with jQuery, I can retrieve additional information about the element using li.find( '.semantics' ).val() To get an element's semantics from JavaScript

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  • C++ inheritance question

    - by user233973
    Hi guys, I have a C++ inheritance related question. I have a set of classes like this (I have not given the complete class structure coz I am lazy :) ). I want to access chiComponent class public methods using com pointer. How should I go about it? Note that I am having to change the object which "com" is pointing to in a lot of places. So I do not think I can have another chiComponent *ccom = <some_cast> com; ccom.chiComponentMethod() How should I go about it? class Component{ }; class chiComponent : public Component { public: void chiComponentMethod() { cout << "Hi! Chi component function called!!"; } } class parent { protected: Component *com; }; class child : public parent{ public: child() { com = new chiComponent(); } } Regards Arun

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  • Possible to convert list of #defines into strings (C++)

    - by brandonC
    Suppose I have a list of #defines in a header file for an external library. These #defines represent error codes returned from functions. I want to write a conversion function that can take as an input an error code and return as an output a string literal representing the actual #define name. As an example, if I have #define NO_ERROR 0 #define ONE_KIND_OF_ERROR 1 #define ANOTHER_KIND_OF_ERROR 2 I would like a function to be able to called like int errorCode = doSomeLibraryFunction(); if (errorCode) writeToLog(convertToString(errorCode)); And have convertToString() be able to auto-convert that error code without being a giant switch-case looking like const char* convertToString(int errorCode) { switch (errorCode) { case NO_ERROR: return "NO_ERROR"; case ONE_KIND_OF_ERROR: return "ONE_KIND_OF_ERROR"; ... ... ... I have a feeling that if this is possible, it would be possible using templates and metaprogramming, but that would only work the error codes were actually a type and not a bunch of processor macros. Thanks

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  • Printing escape character

    - by danutenshu
    When I am given "d""\"/""b", I need to print out the statement character for character. (d, b, a slash, a backslash, and 5 quotes) in C++. The only errors that show now are the lines if(i.at(j)="\\") and else if(i.at(j)="\""). Also, how should the outside double apostrophes be excluded? #include <iostream> #include <cstdlib> using namespace std; int main (int argc, const char* argv[] ) { string i= argv[1]; for (int j=0; j>=sizeof(i)-1; j++) { if(i.at(j)="\\") { cout << "\\"; } else if(i.at(j)="\"") { cout << "\""; } else { cout << i.at(j); } } return 0; }

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  • View is moved 3 pixels

    - by Jakub
    Hello, In my app I move the table view (in order to make the text fields visible when the keyboard appears). The view is looks following: This is the code I use for resizing the view and moving it up: static const NSUInteger navBarHeight = 44; CGRect appFrame = [[UIScreen mainScreen] applicationFrame]; tableView.frame = CGRectMake(0, navBarHeight, appFrame.size.width, appFrame.size.height-navBarHeight-216); //216 for the keyboard NSIndexPath *indPath = [self getIndexPathForTextField:textField]; //get the field the view should scroll to [tableView scrollToRowAtIndexPath:indPath atScrollPosition:UITableViewScrollPositionMiddle animated:YES]; The problem is that when the view is moved up it also moves 3 pixels into right direction (it is hard to see the difference in the screenshot, but it is visible when the animation is on and I measured the difference with PixelStick tool). Here it is how it looks after the move: My analysis shows that scrolling the table does not influence the move to the right. Any ideas what is wrong in the code above that makes the view move to the right?

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  • Official definition of CSCI (Computer Software Configuration Item)

    - by Andreas_D
    I'm looking for the most official definition of CSCI / Configuration Item - not just what it is but what we have to deliver / can expect when a contract defines subsystems which shall be developed as configuration items. I spend some time with my famous search tool and found a lot of explanations for CSCI (wikipedia, acronym directories, ...) but I haven't found a standard or a pointer to a standard (like ISO-xxx) yet which tells (1) what it is and (2) what has to be done from a QM/CM point of view. I just ask, because a contractors QM representative stated during an acceptance test, that CI only requires to not forget the CI in the configuration plan and to assign a serial number ... I expected to see some SRS, SDD, ICD, SVD, SIP, ... documents and acceptance test documentation for those subsystems...

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