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  • Declaring a data type dynamically in C++

    - by Bobby
    I want to be able to do the following: I have an array of strings that contain data types: string DataTypeValues[20] = {"char", "unsigned char", "short", "int"}; Then later, I would like to create a variable of one of the data types at runtime. I won't know at compile time what the correct data type should be. So for example, if at runtime I determined a variable x needed to be of type int: DataTypeValues[3] x = 100; Obviously this won't work, so how could I do something like this?

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  • Passing arguments to UILabel [ 2 ] *

    - by DesperateLearner
    I'm trying to call a method of the below (Scroll animation class) type from a viewcontroller class. -(void)CreateLabel:(CGRect )frame andLabel:(UILabel *[NUM_LABELS])label andview:(UIView *)view; I got some errors when I tried passing the argument. Any suggestion on how to call this? This is how I called that method ScrollAnimation *newAnimation = [[ScrollAnimation alloc] init]; [newAnimation CreateLabel:CGRectMake(0, 50, 300,30) andLabel:animateLabel[NUM_LABELS] andview:self.view]; I have the error /Volumes/Red Drive/CarTransition/CarTransition/ViewController.m:120:66: Implicit conversion of an Objective-C pointer to 'UILabel **' is disallowed with ARC /Volumes/Red Drive/CarTransition/CarTransition/ViewController.m:120:66: Incompatible pointer types sending 'UILabel *__strong' to parameter of type 'UILabel **'

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  • Casting a Calculated Column in a MySQL view.

    - by Chris Brent
    I have a view that contains a calculated column. Is there are a way to cast it as a CHAR or VARCHAR rather than a VARBINARY ? Obviously, I have tried using CAST(... as CHAR) but it gives an error. Here is a simple replicable example. CREATE VIEW view_example AS SELECT concat_ws('_', lpad(9, 3,'0'), lpad(1,3,'0'), date_format(now(),'%Y%m%d%H%i%S')) AS calculated_field_id; This is how my view is created: describe view_example; +---------------------+---------------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +---------------------+---------------+------+-----+---------+-------+ | calculated_field_id | varbinary(27) | YES | | NULL | | +---------------------+---------------+------+-----+---------+-------+ select version(); +-----------------------+ | version() | +-----------------------+ | 5.0.51a-community-log | +-----------------------+

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  • strftimedoesnt display year correctly

    - by paultop6
    Hi guys, i have the following code below: const char* timeformat = "%Y-%m-%d %H:%M:%S"; const int timelength = 20; char timecstring[timelength]; strftime(timecstring, timelength, timeformat, currentstruct); cout << "timecstring is: " << timecstring << "\n"; currentstruct is a tm*. The cout is giving me the date in the correct format, but the year is not 2010, but 3910. I know there is something to do with the year cound starting at 1900, but im not sure how to get strftime to recognise this and not add 1900 to the value of 2010 that is there, can anyone help. Regards Paul

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  • Question about C Pointers (just learning)

    - by Mike
    I am curious as to why this is an error and what the error message means. Here is some code. int *x[] = {"foo", "bar", "baz"}; int *y[] = {"foo", "bar", "baz"}; x = y; I try to compile and I get this: error: incompatible types when assigning to type ‘char [3]’ from type ‘char *’ Question #1 why is this an error? and Question #2 why are the types different? Thanks for you help.

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  • How to call operator<< on "this" in a descendant of std::stringstream?

    - by romkyns
    class mystream : public std::stringstream { public: void write_something() { this << "something"; } }; This results in the following two compile errors on VC++10: error C2297: '<<' : illegal, right operand has type 'const char [10]' error C2296: '<<' : illegal, left operand has type 'mystream *const ' Judging from the second one, this is because what this points at can't be changed, but the << operator does (or at least is declared as if it does). Correct? Is there some other way I can still use the << and >> operators on this?

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  • [c++] upload image to imageshack

    - by cinek1lol
    Hi. I would like to send pictures via a program written in C + + I wrote such a thing using curl.exe WinExec("C:\\curl\\curl.exe -H Expect: -F \"fileupload=@C:\\curl\\ok.jpg\" -F \"xml=yes\" -# \"http://www.imageshack.us/index.php\" -o data.txt -A \"Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8.1.1) Gecko/20061204 Firefox/2.0.0.1\" -e \"http://www.imageshack.us\"", NULL); This only works that I would like to send pictures to a variable pre-loaded char (you know what I mean? first reads the pictures into a variable and then send that variable), because now I have to specify the path to the images on disk I wanted to make this program was written in C + + using the curl library, and not the exe. I found it such a program (which some have modified) #include <stdio.h> #include <string.h> #include <iostream> #include <curl/curl.h> #include <curl/types.h> #include <curl/easy.h> int main(int argc, char *argv[]) { CURL *curl; CURLcode res; struct curl_httppost *formpost=NULL; struct curl_httppost *lastptr=NULL; struct curl_slist *headerlist=NULL; static const char buf[] = "Expect:"; curl_global_init(CURL_GLOBAL_ALL); /* Fill in the file upload field */ curl_formadd(&formpost, &lastptr, CURLFORM_COPYNAME, "send", CURLFORM_FILE, "nowy.jpg", CURLFORM_END); curl_formadd(&formpost, &lastptr, CURLFORM_COPYNAME, "nowy.jpg", CURLFORM_COPYCONTENTS, "nowy.jpg", CURLFORM_END); curl_formadd(&formpost, &lastptr, CURLFORM_COPYNAME, "submit", CURLFORM_COPYCONTENTS, "send", CURLFORM_END); curl = curl_easy_init(); headerlist = curl_slist_append(headerlist, buf); if(curl) { curl_easy_setopt(curl, CURLOPT_URL, "http://www.imageshack.us/index.php"); if ( (argc == 2) && (!strcmp(argv[1], "xml=yes")) ) curl_easy_setopt(curl, CURLOPT_HTTPHEADER, headerlist); curl_easy_setopt(curl, CURLOPT_HTTPPOST, formpost); res = curl_easy_perform(curl); curl_easy_cleanup(curl); curl_formfree(formpost); curl_slist_free_all (headerlist); } system("pause"); return 0; } I will be grateful for any help

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  • Sending while recieving in C

    - by Spidfire
    Ive made a piece of code in whats on my server, the problem is that it doesnt send while im recieving? so if i send something to client 1 to client 2, client2 only recieves if he sends something himself.. how can i solve this ? /* Thread*/ while (! stop_received) { nr_bytes_recv = recv(s, buffer, BUFFSIZE, 0); if(strncmp(buffer, "SEND", 4) == 0) { char *message = "Text asads \n"; rv = send(users[0].s, message, strlen(message), 0); rv = send(users[1].s, message, strlen(message), 0); if (rv < 0) { perror("Error sending"); exit(EXIT_FAILURE); } }else{ char *message = "Unknown command \n"; rv = send(s, message, strlen(message), 0); if (rv < 0) { perror("Error sending"); exit(EXIT_FAILURE); } } }

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  • c: memory allocation (what's going on)

    - by facha
    Hi, everyone Please take a look at this piece of code. I'm allocating one byte for the first variable and another byte for the second one. However, it seems like the compiler allocates more (or I'm missing something). The program outputs both strings, even though their length is more the one byte. void main() { char* some1 = malloc(1); sprintf(some1,"cool"); char* some2 = malloc(1); sprintf(some2,"face"); printf("%s ",some1); printf("%s\n",some2); } Please, could anyone spot some light on what's going on when memory is being allocated.

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  • Need MYSQL query for finding lowest score per game player

    - by Chris Barnhill
    I have a game on Facebook called Rails Across Europe. I have a Best Scores page where I show the players with the best 20 scores, which in game terms refers to the lowest winning turn. The problem is that there are a small number of players who play frequently, and their scores dominate the page. I'd like to make the scores page open to more players. So I thought that I could display the single lowest winning turn for each player instead of displaying all of the lowest winning turns for all players. The problem is that the query for this eludes me. So I hope that one of you brilliant StackOverflow folks can help me with this. I have included the relevant MYSQL table schemas below. Here are the the table relationships: player_stats contains statistics for either a game in progress or a completed game. If a game is in progress, winning_turn is zero (which means that games with a winning_turn of zero should not be included in the query). player_stats has a game_player table id reference. game_player contains data describing games currently in progress. game_player has a player table id reference. player contains data describing a person who plays the game. Here's the query I'm currently using: 'SELECT p.fb_user_id, ps.winning_turn, gp.difficulty_level, c.name as city_name, g.name as goods_name, d.cost FROM game_player as gp, player as p, player_stats as ps, demand as d, city as c, goods as g WHERE p.status = "ACTIVE" AND gp.player_id = p.id AND ps.game_player_id = gp.id AND d.id = ps.highest_demand_id AND c.id = d.city_id AND g.id = d.goods_id AND ps.winning_turn > 0 ORDER BY ps.winning_turn ASC, d.cost DESC LIMIT '.$limit.';'; Here are the relevant table schemas: -- -- Table structure for table `player_stats` -- CREATE TABLE IF NOT EXISTS `player_stats` ( `id` int(11) NOT NULL auto_increment, `game_player_id` int(11) NOT NULL, `winning_turn` int(11) NOT NULL, `highest_demand_id` int(11) NOT NULL, PRIMARY KEY (`id`), KEY `game_player_id` (`game_player_id`,`highest_demand_id`) ) ENGINE=InnoDB DEFAULT CHARSET=utf8 AUTO_INCREMENT=3814 ; -- -- Table structure for table `game_player` -- CREATE TABLE IF NOT EXISTS `game_player` ( `id` int(10) unsigned NOT NULL auto_increment, `game_id` int(10) unsigned NOT NULL, `player_id` int(10) unsigned NOT NULL, `player_number` int(11) NOT NULL, `funds` int(10) unsigned NOT NULL, `turn` int(10) unsigned NOT NULL, `difficulty_level` enum('STANDARD','ADVANCED','MASTER','ULTIMATE') NOT NULL, `date_last_used` datetime NOT NULL, PRIMARY KEY (`id`), KEY `game_id` (`game_id`,`player_id`) ) ENGINE=InnoDB DEFAULT CHARSET=utf8 AUTO_INCREMENT=3814 ; -- -- Table structure for table `player` -- CREATE TABLE IF NOT EXISTS `player` ( `id` int(11) NOT NULL auto_increment, `fb_user_id` char(255) NOT NULL, `fb_proxied_email` text NOT NULL, `first_name` char(255) NOT NULL, `last_name` char(255) NOT NULL, `birthdate` date NOT NULL, `date_registered` datetime NOT NULL, `date_last_logged_in` datetime NOT NULL, `status` enum('ACTIVE','SUSPENDED','CLOSED') NOT NULL, PRIMARY KEY (`id`), KEY `fb_user_id` (`fb_user_id`) ) ENGINE=InnoDB DEFAULT CHARSET=utf8 AUTO_INCREMENT=1646 ;

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  • quick sort problem

    - by farka
    I use qsort from C libary and I have datatype Element_type **pElement and Element_type is struct typedef element_type {int ,char ....} example, and i call quicksor function with qsort(*pElement,iCountElement,(size_t)sizeof(Element_type),compare); and callback function static int compare(const void *p1, const void *p2) { Element_type *a1 = (Element_type *)p1; Element_type *a2 = (Element_type *)p2; return ( (a2)->iServiceId < (a1)->iServiceId ); } but I always get segmentation fault. Why?

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  • Storing objects in STL vector - minimal set of methods

    - by osgx
    Hello What is "minimal framework" (necessary methods) of object, which I will store in STL <vector>? For my assumptions: #include <vector> #include <cstring> using namespace std; class Doit { private: char *a; public: Doit(){a=(char*)malloc(10);} ~Doit(){free(a);} }; int main(){ vector<Doit> v(10); } gives *** glibc detected *** ./a.out: double free or corruption (fasttop): 0x0804b008 *** Aborted and in valgrind: malloc/free: 2 allocs, 12 frees, 50 bytes allocated.

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  • Scala, make my loop more functional

    - by Pengin
    I'm trying to reduce the extent to which I write Scala (2.8) like Java. Here's a simplification of a problem I came across. Can you suggest improvements on my solutions that are "more functional"? Transform the map val inputMap = mutable.LinkedHashMap(1->'a',2->'a',3->'b',4->'z',5->'c') by discarding any entries with value 'z' and indexing the characters as they are encountered First try var outputMap = new mutable.HashMap[Char,Int]() var counter = 0 for(kvp <- inputMap){ val character = kvp._2 if(character !='z' && !outputMap.contains(character)){ outputMap += (character -> counter) counter += 1 } } Second try (not much better, but uses an immutable map and a 'foreach') var outputMap = new immutable.HashMap[Char,Int]() var counter = 0 inputMap.foreach{ case(number,character) => { if(character !='z' && !outputMap.contains(character)){ outputMap2 += (character -> counter) counter += 1 } } }

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  • Solving C++ 'target of assignment not really an lvalue' errors

    - by Jason
    Given this code: void FrMemCopy(void *to, const void *from, size_t sz) { size_t sz8 = sz >> 3; size_t sz1 = sz - (sz8 << 3); while (sz8-- != 0) { *((double *)to)++ = *((double *)from)++; } while (sz1-- != 0) { *((char *)to)++ = *((char *)from)++; } } I am receiving target of assignment not really an lvalue warnings on the 2 lines inside the while loops. Can anyone break down those lines? a cast then an increment? What is a simplier way to write that? What does the error mean?

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  • C++ DWORD* to BYTE*

    - by NomeSkavinski
    My issue, i am trying to convert and array of dynamic memory of type DWORD to a BYTE. Fair enough i can for loop through this and convert the DWORD into a BYTE per entry. But is their a faster way to do this? to take a pointer to DWORD data and convert the whole piece of data into a pointer to BYTE data? such as using a memcpy operation? I feel this is not possible, im not requesting an answer just an experienced opinion on my approach, as i have tried testing both approaches but seem to fail getting to a solution on my second solution. Thanks for any input, again no answers just a point in the right direction. Nor is this a homework question, i felt that had to be mentioned.

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  • parsing command option with default values and range constrains in C

    - by agramfort
    Hi, I need to parse command line arguments in C. My arguments are basically int or float with default values and range constrains. I've started to implement something that look like this: option_float(float* out, int argc, char* argv, char* name, description, float default_val, int is_optional, float min_value, float max_value) which I call for example with: float* pct; option_float(pct, argc, argv, "pct", "My super percentage option", 50, 1, FALSE, 0, 100) however I don't want to reinvent the wheel ! My objective is to have error checking of range constrains, throw an error when the option is not optional and is not set. And generate the help message usually given by usage() function. The usage text would look like this: --pct My super percentage option (default : 50). Should be in [0, 100] I've started with getopt but it is too limited for what I want to do and I feel it still requires me to write too much code for a simple usecase like this. thanks

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  • How do you detach an array of strings from shared memory? C

    - by Tim
    I have: int array_id; char* records[10]; // get the shared segment if ((array_id = shmget(IPC_PRIVATE, 1, 0666)) == -1) { perror("Array Creating"); } // attach records[0] = (char*) shmat(array_id, (void*)0, 0); if ((int) *records == -1) { perror("Array Attachment"); } which works fine, but when i try and detach i get an "invalid argument" error. // detach int error; if( (error = shmdt((void*) records[0])) == -1) { perror(array detachment); } any ideas? thank you

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  • Need recommendation for object serialization library in c++

    - by michael
    Hi, I am looking for recommendation for object serialization/deserialization library in c++? Which one are the most advanced and open-sourced? Can it handle Any class that users defined? Object hierarchy (parent and child classes)? A Tree of objects? Class A has an attribute of Class B which has an attribute of Class C? STL containers? Class A has a vector of Class B? A cyclic of objects? Class A has a pointer pointing to B which has a pointer to A? I find boost serialization library. I am not sure what is its limitation from http://www.boost.org/doc/libs/1_42_0/libs/serialization/doc/tutorial.html

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  • read successive frames OpenCV using cvQueryframe

    - by AtharvaI
    Hi all I have a basic question in regards to cvQueryFrame() in OpenCV. I have the following code: IplImage *frame1,*frame2; frame1 = cvQueryFrame(capture); frame2 = cvQueryFrame(capture); Now my question is: if frame1 is a pointer to the first frame, is frame2 a pointer to the 2nd frame? So will the two cvQueryFrame() calls read successive frames? I thought I'd check myself first but the pointers frame1,frame2 seem to have the same hex value. :s I just need to capture two frames at a time and then need to process them. Thanks in advance

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  • Why do i get segfault at the end of the application after everything's beed done properly ?

    - by VaioIsBorn
    #include <string.h> #include <stdlib.h> #include <stdio.h> int main(void) { unsigned char *stole; unsigned char pass[] = "m4ak47"; printf("Vnesi password: \t"); scanf("%s", stole); if(strncmp(stole, pass, sizeof(pass)) != 0) { printf("wrong password!\n"); exit(0); } else printf("Password correct\n"); printf("some stuf here...\n\n"); return 0; } This program is working nice, but with one problem - if the password is correct then it DOES do the printing of 'some stuf here...' but it also shows me segmentation fault error at the end. Why ?

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  • C++ String pointers

    - by gnm
    In my previous app I had an object like this: class myType { public: int a; string b; } It had a lot of instances scattered everywhere and passed around to nearly every function. The app was slow. Profiling said that 95% of time is eaten by the string allocator function. I know how to work with the object above, but not how to work with string pointers. class myType { public: int a; string* b; } They told me to use pointers as above. How much faster is it with a string pointer? What is copied when I copy the object? How to the following using the class with the pointer: Access the string value Modify the string value without modifying the one in the object (copy?) General things that change if I use string pointers?

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  • Please see following code and answer

    - by user323422
    template <class T> class _cExplicitInstation { public: void show1(T c) { double d =10.02 ; std::cout<<c; } void show2(T d) { std::cout<<d; } }; template _cExplicitInstation<char>; template void _cExplicitInstation<int>::show1(int c); int main() { _cExplicitInstation<char> abc; _cExplicitInstation<int>().show2(10);// it should show error as i have // explicitly declare for show1() function but its working // can u tell why? }

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  • Flex, continuous scanning stream (from socket). Did I miss something using yywrap()?

    - by Diederich Kroeske
    Working on a socketbased scanner (continuous stream) using Flex for pattern recognition. Flex doesn't find a match that overlaps 'array bounderies'. So I implemented yywrap() to setup new array content as soon yylex() detects < (it will call yywrap). No success so far. Basically (for pin-pointing my problem) this is my code: %{ #include <stdio.h> #include <string.h> #include <stdlib.h> #define BUFFERSIZE 26 /* 0123456789012345678901234 */ char cbuf1[BUFFERSIZE] = "Hello everybody, lex is su"; // Warning, no '\0' char cbuf2[BUFFERSIZE] = "per cool. Thanks! "; char recvBuffer[BUFFERSIZE]; int packetCnt = 0; YY_BUFFER_STATE bufferState1, bufferState2; %} %option nounput %option noinput %% "super" { ECHO; } . { printf( "%c", yytext[0] );} %% int yywrap() { int retval = 1; printf(">> yywrap()\n"); if( packetCnt <= 0 ) // Stop after 2 { // Copy cbuf2 into recvBuffer memcpy(recvBuffer, cbuf2, BUFFERSIZE); // yyrestart(NULL); // ?? has no effect // Feed new data to flex bufferState2 = yy_scan_bytes(recvBuffer, BUFFERSIZE); // packetCnt++; // Tell flex to resume scanning retval = 0; } return(retval); } int main(void) { printf("Lenght: %d\n", (int)sizeof(recvBuffer)) ; // Copy cbuf1 into recvBuffer memcpy(recvBuffer, cbuf1, BUFFERSIZE); // packetCnt = 0; // bufferState1 = yy_scan_bytes(recvBuffer, BUFFERSIZE); // yylex(); yy_delete_buffer(bufferState1); yy_delete_buffer(bufferState2); return 0; } This is my output: dkmbpro:test dkroeske$ ./text Lenght: 26 Hello everybody, lex is su>> yywrap() per cool. Thanks! >> yywrap() So no match on 'super'. According to the doc the lexxer is not 'reset' between yywrap's. What do I miss? Thanks.

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  • reading unicode

    - by user121196
    I'm using java io to retrieve text from a server that might output character such as é. then output it using System.err, they turn out to be '?'. I am using UTF8 encoding. what's wrong? int len=0; char[]buffer=new char[1024]; OutputStream os = sock.getOutputStream(); InputStream is = sock.getInputStream(); os.write(query.getBytes("UTF8"));//iso8859_1")); Reader reader = new InputStreamReader(is, Charset.forName("UTF-8")); do{ len = reader.read(buffer); if (len0) { if(outstring==null)outstring=new StringBuffer(); outstring.append(buffer,0,len); } }while(len0); System.err.println(outstring);

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