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  • Write a recursive function in C that converts a number into a string

    - by user3501779
    I'm studying software engineering, and came across this exercise: it asks to write a recursive function in C language that receives a positive integer and an empty string, and "translates" the number into a string. Meaning that after calling the function, the string we sent would contain the number but as a string of its digits. I wrote this function, but when I tried printing the string, it did print the number I sent, but in reverse. This is the function: void strnum(int n, char *str) { if(n) { strnum(n/10, str+1); *str = n%10 + '0'; } } For example, I sent the number 123 on function call, and the output was 321 instead of 123. I also tried exchanging the two lines within the if statement, and it still does the same. I can't figure out what I did wrong. Can someone help please? NOTE: Use of while and for loop statements is not allowed for the exercise.

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  • How to receive a arg from command line in C

    - by 115599yy
    Hi everyone: I want to write a program to receive a argument from command line. It's like a kind of atof(). There my program goes: 9 char s[] = "3.1415e-4"; 10 if (argc == 1) { 11 printf("%e\n",atof(s)); 12 } 13 else if (argc == 2) { 14 //strcpy(s, argv[1]); 15 printf("%e\n",atof(argv[1])); 16 } 1.should I just use argv[1] for the string to pass to my atof(), or, put it into s[]? 2.If I'd better put it in s[], is there some build-in function to do this "put" work? maybe some function like strcpy()?? thanks.

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  • Call a C++ constructor from an Objective C class

    - by syvex
    How can I call a C++ constructor from inside an Objective C class? class CppClass { public: CppClass(int arg1, const std::string& arg2): _arg1(arg1), _arg2(arg2) { } // ... private: int _arg1; std::string _arg2; }; @interface ObjC: NSObject { CppClass _cppClass; } @end @implementation ObjC - (id)init { self = [super init]; if ( self ) { // what is the syntax to call CppClass::CppClass(5, "hello") on _cppClass? } return self; } @end

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  • Any side effect of not using USES_CONVERSION

    - by Yan Cheng CHEOK
    Recently, I have a utilities function of // T2CA #include "ATLCONV.H" std::string Utils::CString2String(const CString& cString) { #if _MSC_VER > 1200 // Convert a TCHAR string to a LPCSTR // construct a std::string using the LPCSTR input CT2CA tmp(cString); std::string strStd (tmp); #else // Deprecated in VC2008. // construct a std::string using the LPCSTR input std::string strStd (T2CA (cString)); #endif return strStd; } I do several simple test it seems work fine. However, when I google around, I see most usage of T2CA in VC6, before they call, they will invoke USES_CONVERSION; Is there any thing I had missed out? Shall I invoke my function by : #else // Deprecated in VC2008. // construct a std::string using the LPCSTR input USES_CONVERSION; std::string strStd (T2CA (cString)); #endif

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  • Is there any reason for a blocking call to winsock send() function on Vista to return immediately ?

    - by ivymike
    Hi All, Is there any reason for a blocking call to winsock's send() function on Vista to return immediately ? It works with expected delay on XP and below. I'm wondering if this has got anything to do with auto-tuning feature of Vista. Code: char *pBuffer; // pointer to data int bytes; // total size int i = 0, j=0; while (i < bytes) { j = send(m_sock, pBuffer+i, bytes-i, 0); i+=j; } Thanks, Pavan

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  • How can I load a SQLITE database from a buffer with the C API ?

    - by rockeye
    Hello, I am trying to load a database from the memory instead of opening a .sqlite file. I have read the C/C++ API reference but I can not find the proper method. The buffer I am trying to load is simply an sqlite file loaded in memory. I just want to use this buffer (a const char* array) without using the filesystem (I could have saved this buffer in a file, then load the file, but no). First, I create a memory DB : mErrorCode = sqlite3_open_v2(":memory:", &mSqlDatabase, lMode, NULL); This returns SQLITE_OK, then I tried to use the buffer as a statement and call preparev2(MyDB, MyBufferData, MyBufferLength, MyStatement, NULL) but it's not really a statement, and it returns an error. Same result if I call directly exec(MyDB, MyBufferData, NULL, NULL, NULL); I guess there is an appropriate method to achieve this as it might be common to load a DB from a stream or from decrypted data... Thanks.

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  • NULL pointer dereference in C

    - by user554125
    hey ive got this piece of code. It dereferences a null pointer here. But then there is an and with unsigned int. I really dont understand the whole part. Can someone explain the output.?? struct hi { long a; int b; long c; }; int main() { struct hi ob={3,4,5}; struct hi *ptr=&ob; int num= (unsigned int) & (((struct hi *)0)->b); printf("%d",num); printf("%d",*(int *)((char *)ptr + (unsigned int) & (((struct hi *)0)->b))); } The o/p i get is 44 .But how does it work?

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  • boost timer usage question

    - by stefita
    I have a really simple question, yet I can't find an answer for it. I guess I am missing something in the usage of the boost timer.hpp. Here is my code, that unfortunately gives me an error message: include <boost/timer.hpp> int main() { boost::timer t; } And the error messages are as follows: /usr/include/boost/timer.hpp: In member function ‘double boost::timer::elapsed_max() const’: /usr/include/boost/timer.hpp:59: error: ‘numeric_limits’ is not a member of ‘std’ /usr/include/boost/timer.hpp:59: error: ‘::max’ has not been declared /usr/include/boost/timer.hpp:59: error: expected primary-expression before ‘double’ /usr/include/boost/timer.hpp:59: error: expected `)' before ‘double’ The used library is boost 1.36 (SUSE 11.1). Thanks in advance!

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  • C++ cin returns 0 for integer no matter what the user inputs

    - by kevin dappah
    No matter the cin it continues to to output 0 for score. Why is that? I tried returning the "return 0;" but still no go :/ #include "stdafx.h" #include <iostream> using namespace std; // Variables int enemiesKilled; const int KILLS = 150; int score = enemiesKilled * KILLS; int main() { cout << "How many enemies did you kill?" << endl; cin >> enemiesKilled; cout << "Your score: " << score << endl; return 0; }

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  • Reading in data from a file into an array

    - by Sam
    If I have an options file along the lines of this: size = 4 data = 1100010100110010 And I have a 2d size * size array that I want to populate the values in data into, what's the best way of doing it? To clarify, for the example I have I'd want an array like this: int[4][4] array = {{1,1,0,0}, {0,1,0,1}, {0,0,1,1}, {0,0,1,0}}. (Not real code but you get the idea). Size can be really be any number though. I'm thinking I'd have to read in the size, maloc an array and then maybe read in a string full of data then loop through each char in the data, cast it to an int and stick it in the appropriate index? But I really have no idea how to go about it, have been searching for a while with no luck. Any help would be cool! :)

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  • Query on the scope of local variables in C

    - by darkie15
    All, Consider the following code: void func(void) { int a; printf ("%d", a); } int main(int argc, char **argv) { int a = 3; func(); printf("%d", a); } According to my understanding, the output should be: <junk value><3> Can anyone please confirm my understanding? My basic query is, does the compiler refer to the outer scope for a variable that has been declared but not defined? Regards, darkie

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  • Using methods on 2 input files - 2nd is printing multiple times - Java

    - by Aaa
    I have the following code to read in text, store in a hashmap as bigrams (with other methods to sort them by frequency and do v. v. basic additive smoothing. I had it working great for one language input file (english) and then I want to expand it for the second language input file (japanese - doens;t matter what it is I suppose) using the same methods but the Japanese bigram hashmap is printing out 3 times in a row with diff. values. I've tried using diff text in the input file, making sure there are no gaps in text etc. I've also put print statements at certain places in the Japanese part of the code to see if I can get any clues but all the print statements are printing each time so I can't work out if it is looping at a certain place. I have gone through it with a fine toothcomb but am obviously missing something and slowly going crazy here - any help would be appreciated. thanks in advance... package languagerecognition2; import java.lang.String; import java.io.InputStreamReader; import java.util.*; import java.util.Iterator; import java.util.List.*; import java.util.ArrayList; import java.util.AbstractMap.*; import java.lang.Object; import java.io.*; import java.util.Enumeration; import java.util.Arrays; import java.lang.Math; public class Main { /** public static void main(String[] args) { //training English ----------------------------------------------------------------- File file = new File("english1.txt"); StringBuffer contents = new StringBuffer(); BufferedReader reader = null; try { reader = new BufferedReader(new FileReader(file)); String test = null; //test = reader.readLine(); // repeat until all lines are read while ((test = reader.readLine()) != null) { test = test.toLowerCase(); char[] charArrayEng = test.toCharArray(); HashMap<String, Integer> hashMapEng = new HashMap<String, Integer>(bigrams(charArrayEng)); LinkedHashMap<String, Integer> sortedListEng = new LinkedHashMap<String, Integer>(sort(hashMapEng)); int sizeEng=sortedListEng.size(); System.out.println("Total count of English bigrams is " + sizeEng); LinkedHashMap<String, Integer> smoothedListEng = new LinkedHashMap<String, Integer>(smooth(sortedListEng, sizeEng)); //print linkedHashMap to check values Set set= smoothedListEng.entrySet(); Iterator iter = set.iterator ( ) ; System.out.println("Beginning English"); while ( iter.hasNext()) { Map.Entry entry = ( Map.Entry ) iter.next ( ) ; Object key = entry.getKey ( ) ; Object value = entry.getValue ( ) ; System.out.println( key+" : " + value); } System.out.println("End English"); }//end while }//end try catch (FileNotFoundException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } finally { try { if (reader != null) { reader.close(); } } catch (IOException e) { e.printStackTrace(); } } //End training English----------------------------------------------------------- //Training japanese-------------------------------------------------------------- File file2 = new File("japanese1.txt"); StringBuffer contents2 = new StringBuffer(); BufferedReader reader2 = null; try { reader2 = new BufferedReader(new FileReader(file2)); String test2 = null; //repeat until all lines are read while ((test2 = reader2.readLine()) != null) { test2 = test2.toLowerCase(); char[] charArrayJap = test2.toCharArray(); HashMap<String, Integer> hashMapJap = new HashMap<String, Integer>(bigrams(charArrayJap)); //System.out.println( "bigrams stage"); LinkedHashMap<String, Integer> sortedListJap = new LinkedHashMap<String, Integer>(sort(hashMapJap)); //System.out.println( "sort stage"); int sizeJap=sortedListJap.size(); //System.out.println("Total count of Japanese bigrams is " + sizeJap); LinkedHashMap<String, Integer> smoothedListJap = new LinkedHashMap<String, Integer>(smooth(sortedListJap, sizeJap)); System.out.println( "smooth stage"); //print linkedHashMap to check values Set set2= smoothedListJap.entrySet(); Iterator iter2 = set2.iterator(); System.out.println("Beginning Japanese"); while ( iter2.hasNext()) { Map.Entry entry2 = ( Map.Entry ) iter2.next ( ) ; Object key = entry2.getKey ( ) ; Object value = entry2.getValue ( ) ; System.out.println( key+" : " + value); }//end while System.out.println("End Japanese"); }//end while }//end try catch (FileNotFoundException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } finally { try { if (reader2 != null) { reader2.close(); } } catch (IOException e) { e.printStackTrace(); } } //end training Japanese--------------------------------------------------------- } //end main (inner)

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  • How to fill a section within c++ string?

    - by stacker
    Having a string of whitespaces: string *str = new string(); str->resize(width,' '); I'd like to fill length chars at a position. In C it would look like memset(&str[pos],'#', length ); How can i achieve this with c++ string, I tried string& assign( const string& str, size_type index, size_type len ); but this seems to truncat the original string. Is there an easy C++ way to do this? Thanks.

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  • Keeping historic of modification in a database.

    - by mada
    Hi, Im a j2ee developper & we are using hibernatne mapping with a postgres databasae. We have to keep track of any changes occurs in the databse , in others words alls previous & current value of any field should be saved & field can be various types (bytea, int, char...) With a simple table it is easy but we a graph of objets things are more difficult So we have , speaking in a UML point of view, a graph of objects to store in the database with every changes & the user. Any idea or pattern how to do that ? Thanks in advance.

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  • Stringification of a macro value

    - by SF.
    I faced a problem - I need to use a macro value both as string and as integer. #define RECORDS_PER_PAGE 10 /*... */ #define REQUEST_RECORDS \ "SELECT Fields FROM Table WHERE Conditions" \ " OFFSET %d * " #RECORDS_PER_PAGE \ " LIMIT " #RECORDS_PER_PAGE ";" char result_buffer[RECORDS_PER_PAGE][MAX_RECORD_LEN]; /* ...and some more uses of RECORDS_PER_PAGE, elsewhere... */ This fails with a message about "stray #", and even if it worked, I guess I'd get the macro names stringified, not the values. Of course I can feed the values to the final method ( "LIMIT %d ", page*RECORDS_PER_PAGE ) but it's neither pretty nor efficient. It's times like this when I wish the preprocessor didn't treat strings in a special way and would process their content just like normal code. For now, I cludged it with #define RECORDS_PER_PAGE_TXT "10" but understandably, I'm not happy about it. How to get it right?

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  • Context Menu event with QGraphicsWidget

    - by onurozcelik
    In my application I subclass QGraphicsWidget In paint I am drawing a line with pen width 4. I reimplemented boundingRect() and shape(). But I can't catch context menu event every time I click right mouse button. What is the problem.(Pen Width ? ) //Sample code for boundingRect() and shape() QRectF boundingRect() const { qreal rectLeft = x1 < x2 ? x1 : x2; qreal rectTop = y1 < y2 ? y1 : y2; qreal rectWidth = (x1 - x2) != 0 ? abs(x1-x2) : 4; qreal rectHeight = (y1 - y2) != 0 ? abs(y1 -y2) : 4; return QRectF(rectLeft,rectTop,rectWidth,rectHeigt); } QPainterPath shape() { QPainterPath path; path.addRect(boundingRect()); return path; }

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  • What is on the 68000 stack when classic MacOS enters a program?

    - by John Källén
    I'm trying to understand an old classic Mac application's entry point. I've disassembled the first CODE resource (not CODE#0, which is the jump table). The code refers to some variables off the stack: a word at 0004(A7), an array of long words of starting at 000C(A7) whose length is the value at 0004(A7), and a final long word beyond that array that seems to be a pointer to a character string. The array of long words looks like strings at first glance, so it looks superficially like we're dealing with an (int argc, char ** argv) situation, except the "argv" array is inline in the stack frame. What should a program be expecting on its stack / registers when it first gets called by the Mac OS?

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  • SQL Server 2008 Stored Procedure

    - by user238319
    I cannot store the date data type variables using stored procedure. My code is: ALTER PROCEDURE [dbo].[Access1Register] -- Add the parameters for the stored procedure here @MobileNumber int, @CitizenName varchar(50), @Dob char(8), @VerificationCode int AS BEGIN -- SET NOCOUNT ON added to prevent extra result sets from -- interfering with SELECT statements. SET NOCOUNT ON; -- Insert statements for procedure here select CAST(@dob As DATE) Insert Into Access1 (MobileNo,CitizenName,Dob,VerificationCode) values(@MobileNumber,@CitizenName,@Dob,@VerificationCode) go If I exec this procedure it is executing, but there is an error occured in the date type variable. It's raising the error as invalid item '-'.

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  • calling resize on std vector of pointers crashed

    - by user11869
    The problem can be reproduced using VS 2013 Express. It crashed when internal vector implementation tried to deallocate the original vector. However, the problem can solved by using 'new' instead of 'malloc'. Anyone can shed some light on this? struct UndirectedGraphNode { int label; vector<UndirectedGraphNode *> neighbors; UndirectedGraphNode(int x) : label(x) {}; }; int main(int argc, char** argv) { UndirectedGraphNode* node1 = (UndirectedGraphNode*)malloc(sizeof(UndirectedGraphNode)); node1->label = 0; node1->neighbors.resize(2); return 0; }

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  • How to use #ifdef entities as part of functions in header files

    - by Crazyjavahacking
    I would like to ask if it is possible to use the entities defined in #ifdef block in header files. To be clear, I have following code: #ifdef #include <winsock2.h> #define SOCKET_HANDLE SOCKET #define CONNECTION_HANDLE SOCKET #endif SOCKET_HANDLE createServerSocket(const char* hostAddress, short port); I am Java developer and this seems completely fine for me. However compiler has a problem with this. Can you explain why is that code a problem? Also how can I force to compile it. (The idea is to have generic interface and conditional compilation to determine real types according to running platform at compile time.) Thanks

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  • HTAccess mod rewrite issue using QSA

    - by Matt
    Hey, I want to add a parameter to a URL but currently it isnt showing in the $_GET global. A snippet from my htaccess file is as below: RewriteRule ^account/blogs/([0-9]+)/([^\s?]+)/?$ /account/blog.php?blogId=$1 [L,QSA] Then in my php code i want to add a link such as: /account/blogs/1/ThisIsWhereTheTitleGoes?delete=1 The wildcard (any char but space) option is for the blog title as i never know what it would be. I know want to add a query string param on the end such as ?delete=1. I however dont want this as part of the rewrite. Does anybody know how to so this? Thanks

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  • Using Boost statechart, how can I transition to a state unconditionally?

    - by nickb
    I have a state A that I would like to transition to its next state B unconditionally, once the constructor of A has completed. Is this possible? I tried posting an event from the constructor, which does not work, even though it compiles. Thanks. Edit: Here is what I've tried so far: struct A : sc::simple_state< A, Active > { public: typedef sc::custom_reaction< EventDoneA > reactions; A() { std::cout << "Inside of A()" << std::endl; post_event( EventDoneA() ); } sc::result react( const EventDoneA & ) { return transit< B >(); } }; This yields the following runtime assertion failure: Assertion failed: get_pointer( pContext_ ) != 0, file /includ e/boost/statechart/simple_state.hpp, line 459

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  • optimize a string.Format + replace.

    - by acidzombie24
    I have this function. The visual studio profile marked the line with string.Format as hot and were i spend much of my time. How can i write this loop more efficiently? public string EscapeNoPredicate(string sz) { var s = new StringBuilder(sz); s.Replace(sepStr, sepStr + sepStr); foreach (char v in IllegalChars) { string s2 = string.Format("{0}{1:X2}", seperator, (Int16)v); s.Replace(v.ToString(), s2); } return s.ToString(); }

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  • Calling some functions before main in C

    - by minjang
    I'd like to do some stuffs before main function. I have multiple source files. In each file, there is some work that needs to be done before main. It was no problem in C++, but problematic with C. In C++, this can be done by two ways: Exploiting a constructor of a global class/struct. Calling a function to a global variable For example, static const int __register_dummy_ = __AddRegisterMetaInfo(...); However, in C, either ways is impossible. Obviously, there is no constructor. So, the first option is inherently impossible. I thought that the second option would be possible, but not compiled in C (I tested only with Visual C++. It gives C2099.). C only allows a constant to a non-automatic variable. Is there any way to call some functions before main?

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  • GCC fatal error: stdio.h: No such file or directory

    - by user2615799
    I'm trying to compile a program in C on OS X 10.9 with GCC 4.9 (experimental). For some reason, I'm getting the following error at compile time: gcc: fatal error: stdio.h: No such file or directory I then tried a simple Hello World program: #include <stdio.h> int main(int *argc, const char *argv[]) { printf("Hello, world!"); return 0; } Again, upon running gcc -o ~/hello ~/hello.c, I got the same error. I'm using an experimental version of gcc, but it seems implausible that there would be a release which generated errors upon importing stdio. What could be causing this issue, and how can it be fixed?

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