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  • explain this macro

    - by deostroll
    #define __T(x) L ## x Found in code from one of the MFC source header file. It is mostly used for converting strings to ........ (I don't know what). If I am correct it converts strings to LPCTSTR...don't know what that type is either... I can't seem to convert char* into LPCTSTR. While MFC file handling, the following code will always return error while trying to open the file... char* filepath = "C:\\Program Files\\Microsoft Office\\Office12\\BITMAPS\\STYLES\\GLOBE.WMF"; if( !file.Open((LPCTSTR)filepath , CFile::modeRead, &fexp) ) { fexp.ReportError(); return 1; } But instead if I wrote it this way, it doesn't give error: if( !file.Open( _T("C:\\Program Files\\Microsoft Office\\Office12\\BITMAPS\\STYLES\\GLOBE.WMF") , CFile::modeRead, &fexp) ) { fexp.ReportError(); return 1; } I am looking at passing a variable as the first argument to the CFile::Open() method.

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  • Linker Error : Statically Linking of Boost Serialization Library

    - by Manikanda raj S
    I'm trying to link the Boost Serialization Library to my Code. But it doesn't seem to be working. g++ serialize.cpp -L"/usr/local/lib/libboost_serialization.a" Error : /tmp/ccw7eX4A.o: In function boost::archive::text_oarchive::text_oarchive(std::basic_ostream<char, std::char_traits<char> >&, unsigned int)': serializep.cpp:(.text._ZN5boost7archive13text_oarchiveC2ERSoj[_ZN5boost7archive13text_oarchiveC5ERSoj]+0x25): undefined reference toboost::archive::text_oarchive_impl::text_oarchive_impl(std::basic_ostream &, unsigned int)' .......... collect2: ld returned 1 exit status But when i link as a shared library, g++ serialize.cpp -lboost_serialization , it works fine. What am i missing here P.S : Other StackOverflow posts with the same question has no answers that work for the above error

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  • Sending while receiving in C

    - by Spidfire
    I've made a piece of code in what's on my server, the problem is that it doesn't send while im receiving. so if i send something to client 1 to client 2, client2 only receives 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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  • Read options from file

    - by Devel
    I would like to write a function which will read values from a text file and write them to variables. For example my file is: mysql_server localhost mysql_user root mysql_passworg pospaz mysql_database testgenerator log log.txt username admin password abcd and I have the same variables as the first word in the line. So how to make the function read data from file and do sth like this: char *mysql_server = localhost; char *mysql_user = root; ... I have no idea even how to start writing it...

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  • What is wrong with my loop?

    - by user3966541
    I have the following loop and don't understand why it only runs once: std::vector<sf::RectangleShape> shapes; const int res_width = 640; const int res_height = 480; for (int x = 0; x < res_width / 50; x += 50) { for (int y = 0; y < res_height / 50; y += 50) { sf::RectangleShape shape(sf::Vector2f(50, 50)); shape.setPosition(x * 50, y * 50); sf::Color color = (x % 2 == 0) ? sf::Color::Green : sf::Color::Red; shape.setFillColor(sf::Color::Green); shapes.push_back(shape); } }

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  • referencing struct fields in c with square brackets and an index instead of . and ->?

    - by lsiebert
    Assuming I have a structure such as: typedef struct { char * string1; char * string2; } TWO_WORDS; such that all the fields are of the same type, and my main has TWO_WORDS tw; can I reference string1 with tw[0] and string2 with two[1]? If so: is this part of the c standard? do i have to cast the struct to an array first? what about fields which are different sizes in memory what about fields which are different types but the same size? can you do pointer arithmetic within a structure? -

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  • Is it possible for a parent to use a child's constant or static variables from inside a static metho

    - by ryeguy
    Below is an example of what I'm trying to do. The parent can't access any of the child's variables. It doesn't matter what technique I use (static or constants), I just need some kind of functionality like this. class ParentClass { public static function staticFunc() { //both of these will throw a (static|const) not defined error echo self::$myStatic; echo self::MY_CONSTANT; } } class ChildClass extends ParentClass { const MY_CONSTANT = 1; public static $myStatic = 2; } ChildClass::staticFunc();

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  • Set argument pointer to point to new memory inside a function (without returning it) IN C

    - by user321605
    Hello, Hopefully my title was descriptive enough to attract the right help. I want to write a function that will return 1 thing, and modify a provided pointer in another. My current function declaration is . . . char * afterURL replaceURLS(char * body) What I want to do is copy all of body's data into a new string, and set body to point to this new data. I then want afterURL to point to a location within the new string. My issue is getting the actual pointer that is passed in to this function to point to the new data. Thanks in advance! Rob

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  • Different sizes of same strings - Telnet programming

    - by tommyogp
    Hi all, I have been trying to create an iphone app sending telnet command. However what puzzling me is that the sizes of certain strings are so much different, particularly when they include \n or \r. I listed out a few examples. Please assist. const char *a = "play 25\n"; int sizeBitA1 = sizeof(a); // 8 units int sizeBitA2 = sizeof("play 25\n"); // 9 units const char *b = "\r\n"; int sizeBitB1 = sizeof(b); // 8 units int sizeBitB2 = sizeof("\r\n"); // 3 units

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  • Sending a file from memory (rather than disk) over HTTP using libcurl

    - by cinek1lol
    Hi! I would like to send pictures via a program written in C + +. - OK 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); It works, but I would like to send the pictures from pre-loaded carrier to a variable char (you know what I mean? First off, I load the pictures into a variable and then send the variable), cause now I have to specify the path of the picture on a disk. I wanted to write this program in c++ by using the curl library, not through exe. extension. I have also found such a program (which has been modified by me a bit) #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; }

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  • C++ STL: Trouble with string iterators

    - by Rosarch
    I'm making a simple command line Hangman game. void Hangman::printStatus() { cout << "Lives remaining: " << livesRemaining << endl; cout << getFormattedAnswer() << endl; } string Hangman::getFormattedAnswer() { return getFormattedAnswerFrom(correctAnswer.begin(), correctAnswer.end()); } string Hangman::getFormattedAnswerFrom(string::const_iterator begin, string::const_iterator end) { return begin == end? "" : displayChar(*begin) + getFormattedAnswerFrom(++begin, end); } char Hangman::displayChar(const char c) { return c; } (Eventually, I'll change this so displayChar() displays a - or a character if the user has guessed it, but for simplicity now I'm just returning everything.) When I build and run this from VS 2010, I get a popup box: Debug Assertion Failed! xstring Line: 78 Expression: string iterator not dereferenceable What am I doing wrong?

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  • C++: Vector3 type "wall" ?

    - by anon
    Say I have: class Vector3 { float x, y, z; ... bunch of cuntions .. static operator+(const Vector3&, const Vector3); }; Now, suppose I want to have classes: Position, Velocity, that are exactly like Vector3 (basically, I want typedef Vector3 Position; typedef Vector3 Velocity; Except, given: Position position; Vector3 vector3; Velocity velocity; I want to make sure the following can't happen: position + vector3; vector3 + velocity; velocity + position; What is the best way to achieve this?

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  • How do I compare vectors in C++?

    - by Sam Phelps
    I am trying to compare two vector objects, and return a single vector containing all the chars which appear in both vectors. How would I go about this without writing some horribly complex manual method which compares every char in the first vector to every char in the second vector and using an if to add it to a third vector (which would be returned) if they match. Maybe my lack of real experience with vectors is making me imagine this will be harder than it really is, but I suspect there is some simplier way which I have been unable to find through searching.

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  • define macro in C wont work

    - by Spidfire
    Im trying to make a macro in C that can tell if a char is a hex number ( 0-9 a-z A-Z) #define _hex(x) (((x) >= "0" && (x) <= "9" )||( (x) >= "a" && (x) <= "z") || ((x) >= "A" && (x) <= "Z") ? "true" : "false") this what ive come up with but it wont work with a loop like this char a; for(a = "a" ; a < "z";a++){ printf("%s => %s",a, _hex(a)); } but it gives a error test.c:8: warning: assignment makes integer from pointer without a cast test.c:8: warning: comparison between pointer and integer test.c:9: warning: comparison between pointer and integer test.c:9: warning: comparison between pointer and integer test.c:9: warning: comparison between pointer and integer test.c:9: warning: comparison between pointer and integer test.c:9: warning: comparison between pointer and integer test.c:9: warning: comparison between pointer and integer

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  • Extract inputs from a pointer to array of characters in C / C++

    - by user2066884
    I am writing a command line utility but I cannot find a way to store the commands and arguments. so far I have the following but I get a Segmentation fault: int main(void) { char *command; char *args[MAX_LINE/2 + 1]; int should_run = 1; do{ cout << "cmd> "; int counter = 0; while(cin >> command) { strcpy(args[counter],command); counter++; } cout << args[0] << "\n"; } }

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  • Reading from a file into an array in c

    - by NaNa21
    My file contains a series of numbers (integer, float, integer, float ....), each written on a separate line. The numbers of columns are different from one line to another i.e. 1 2.45 3 1.75 5 3.45 7 2.55 9 3.25 6 1.75 4 3.55 6 2.55 9 2.45 The program should read the contents of the entire file and place the data into an array of type float with an entry for each line. Here is my basic solution, but this is only suitable if I have fixed no of columns. float Read(FILE *pFile) { char line[50]; char letter[5]; fi = fopen("file.txt", "r"); while (fgets(line,200,fi)!=NULL) { sscanf(line,"%f %f %f",&a[i], &a2[i],&a3[i]); printf("%2.0f %2.5f %2.0f\n",a[i],a2[i],a3[i]); } fclose(fi); return a[i]; } Please HELP.

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  • What's the simplest way of defining lexicographic comparison for elements of a class?

    - by the_mandrill
    If I have a class that I want to be able to sort (ie support a less-than concept), and it has several data items such that I need to do lexicographic ordering then I need something like this: struct MyData { string surname; string forename; bool operator<(const MyData& other) const { return surname < other.surname || (surname==other.surname && forename < other.forename); } }; This becomes pretty unmanageable for anything with more than 2 data members. Are there any simpler ways of achieving it? The data members may be any Comparable class.

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  • Adding characters to string

    - by Jamza
    I am currently trying to build a very basic serial shell with my arduino. I am able to get an output from the device using Serial.read() and can get the character it has outputted, but I cannot work out how to then add that character to a longer to form the full command. I tried the logical thing but it doesn't work: char Command[]; void loop(){ if(Serial.available() > 0){ int clinput = Serial.read(); Command = Command + char(clinput); } Can anybody help? Thank You.

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  • Referencing invalid memory locations with C++ Iterators

    - by themoondothshine
    I am a big fan of GCC, but recently I noticed a vague anomaly. Using __gnu_cxx::__normal_iterator (ie, the most common iterator type used in libstdc++, the C++ STL) it is possible to refer to an arbitrary memory location and even change its value without causing an exception! Is this expected behavior? If so, isn't a security loophole? Here's an example: #include <iostream> using namespace std; int main() { basic_string<char> str("Hello world!"); basic_string<char>::iterator iter = str.end(); iter += str.capacity() + 99999; *iter = 'x'; cout << "Value: " << *iter << endl; }

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  • C# equivalent of recv?

    - by mlh
    Hello, I have a portion of C code that I am trying to port over to C#. In my C code, I create a socket and then issue a receive command. The receive command is void receive(mysocket, char * command_buffer) { recv(mysocket, command_buffer, COMMAND_BUFFER_SIZE, 0); } now, the command buffer is returned with new values including command_buffer[8] being a pointer to a string. I'm really confused as to how to do this in C# because C# Read() command specifically takes in bytes and not char. The important part is that I get the pointer to the string. Any ideas?

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  • I was making this program and the server wont send to the client

    - by crstin
    void CApplication::SendData( const char pBuffer[] ) { if( pBuffer == NULL ) { Log()->Write( ELogMessageType_ERROR, "Cannot send NULL message."); return; } // calculate the size of that data unsigned long messageSize = strlen( pBuffer ); // fix our byte ordering messageSize = htonl( messageSize ); if( isServer == true ) { for( unsigned int i = ESocket_CLIENT0; i < ESocket_MAX; ++i ) { // send the message size if( m_Socket[ i ] > 0 ) { if( send( m_Socket[ i ], (char*)&messageSize, sizeof( messageSize ), 0 ) == SOCKET_ERROR ) { Log()->Write( ELogMessageType_ERROR, "[Application] Send error: %i to socket %i", WSAGetLastError(), m_Socket[ i ] ); continue; } // fix our message size back to host ordering messageSize = ntohl(messageSize); // send the actual message if( send( m_Socket[ i ], pBuffer, messageSize, 0 ) == SOCKET_ERROR ) { Log()->Write( ELogMessageType_ERROR, "[Application] Send error: %i to socket %i", WSAGetLastError(), m_Socket[ i ] ); continue; } Log()->Write( ELogMessageType_MESSAGE, "[Application] SEND: %s", pBuffer ); } } }

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  • Abstract class and operator!= in c++

    - by Alessandro Teruzzi
    Hi All, I have problem implementing the operator!= in a set class deriving from an abstact one. The code looks like this: class Abstract { public: //to make the syntax easier let's use a raw pointer virtual bool operator!=(const Abstract* other) = 0; }; class Implementation { SomeObject impl_; //that already implement the operator!= public: bool operator!=(const Abstract* other) { return dynamic_cast<Implementation*>(other)->impl_ != this->impl_; } }; This code works but it has the drawback to use dynamic_cast and I need to handle error in casting operation. This is a generic problem that occur when a function of a concrete class it is trying to using some internal information (not available at the abstract class level) to perform a task. Is there any better way to solve this kind of problem? Cheers

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  • How to split the definition of template friend funtion within template class?

    - by ~joke
    The following example compiles fine but I can't figure out how to separate declaration and definition of operator<<() is this particular case. Every time I try to split the definition friend is causing trouble and gcc complains the operator<<() definition must take exactly one argument. #include <iostream> template <typename T> class Test { public: Test(const T& value) : value_(value) {} template <typename STREAM> friend STREAM& operator<<(STREAM& os, const Test<T>& rhs) { os << rhs.value_; return os; } private: T value_; }; int main() { std::cout << Test<int>(5) << std::endl; }

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  • Program quits if pipe is closed

    - by givemelight
    I am trying to write to a pipe using C++. The following code gets called in an extra thread: void writeToPipe() { int outfifo; char buf[100]; char outfile[] = "out"; mknod(outfile, S_IFIFO | 0666, 0); if ((outfifo = open(outfile, O_WRONLY)) < 0) { perror("Opening output fifo failed"); return false; } int currentTimestamp = (int)time(0); int bufLen = sprintf(bug, "Time is %d.", currentTimestamp); write(outfifo, buf, bufLen); } The thread is called in main using: thread writeThread(writeToPipe); writeThread.detach(); If the pipe is not opened by another process, the C++ program just quits without an error. I don't know how to check if the pipe is opened.

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