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• Magick++ in VS2010 - unresolved external symbol

  - by FlashFan

  Hey guys! I'm trying to use ImageMagick Magick++ for a C++ Project in VS2010. I installed the Library from here: klick Then in my Project, I added c:/program files/ImageMagick-6.6.6-Q16/include to the include folders. Then I tried to use Magick++ with this code: #include <Magick++.h> void main(int argc, char ** argv){ InitializeMagick(*argv); } But this does not work! VS2010 returns the following errors: error LNK2001: unresolved external symbol "__declspec(dllimport) void __cdecl Magick::InitializeMagick(char const *)" (__imp_?InitializeMagick@Magick@@YAXPBD@Z) error LNK1120: 1 unresolved externals What am I doing wrong? Thanks very much for your help!

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• Removing first two elements of a string array in C

  - by sandeep p

  How can I remove first two elements of a string array? I have a code which is something like this. char *x[10]; .............. .............. .............. char *event[20]; event[0]=strtok(x[i]," "); event[1]=strtok(NULL," "); event[2]=strtok(NULL," "); event[3]=strtok(NULL," "); event[4]=strtok(NULL," "); event[5]=strtok(NULL," "); for(i=2;i<length;i++) { strcpy(event[i-2],event[i]); } I observed that only event[0] has proper values. I printed the contents of event[][] before for loop and it displays correctly. Could you please tell me why this is wrong? and a possible solution?

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• Is there a simple script to convert C++ enum to string?

  - by Edu Felipe

  Suppose we have some named enums: enum MyEnum { FOO, BAR = 0x50 }; What I googled for is a script (any language) that scans all the headers in my project and generates a header with one function per enum. char* enum_to_string(MyEnum t); And a implementation with something like this: char* enum_to_string(MyEnum t){ switch(t){ case FOO: return "FOO"; case BAR: return "BAR"; default: return "INVALID ENUM"; } } The gotcha is really with typedefed enums, and unnamed C style enums. Does anybody know something for this? EDIT: The solution should not modify my source, except for the generated functions. The enums are in an API, so using the solutions proposed until now is just not an option.

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• Strange difference between optimized/non optimized microsoft c++ code

  - by Anders Forsgren

  I have a c++ program with a method that looks something like this: int myMethod(int* arr1, int* arr2, int* index) { arr1--; arr2--; int val = arr1[*index]; int val2 = arr2[val]; doMoreThings(val); } With optimizations enabled (/O2) the first line where the first pointer is decremented is not executed. I assume the compiler believes that the arr1 array is not used since it thinks it can remove the decrement. Am I violating some convention in the above code? What could cause this behavior? It is a very old piece of f2c-translated code, the pointer decrement is due to the 1-based indexing of the original code.

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• matlab: putting a circled number onto a graph

  - by Jason S

  I want to put a circled number on a graph as a marker near (but not on) a point. Sounds easy, but I also want to be invariant of zoom/aspect ratio changes. Because of this invariant, I can't draw a circle as a line object (without redrawing it upon rescale); if I use a circle marker, I'd have to adjust its offset upon rescale. The simplest approach I can think of is to use the Unicode or Wingdings characters ① ② ③ etc. in a string for the text() function. But unicode doesn't seem to work right, and the following sample only works with ① and not for the other numbers (which yield rectangle boxes): works: clf; text(0.5,0.5,char(129),'FontName','WingDings') doesn't work (should be a circled 2): clf; text(0.5,0.5,char(130),'FontName','WingDings') What gives, and can anyone suggest a workaround?

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• Same loop giving different output. Java IO

  - by Nitesh Panchal

  Hi, I am facing a very strange problem where the same loop keeps giving me different different output on change of value of BUFFER final int BUFFER = 100; char[] charArr = new char[BUFFER]; StringBuffer objStringBuffer = new StringBuffer(); while (objBufferedReader.read(charArr, 0,BUFFER) != -1) { objStringBuffer.append(charArr); } objFileWriter.write(objStringBuffer.toString()); When i change BUFFER size to 500 it gives me a file of 7 kb when i change BUFFER size to 100000 it gives a file of 400 kb where the contents are repeated again and again. Please help. What should i do to prevent this?

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• Simple doubt related to strings in C (question in an interview)

  - by piemesons

  // The first example: char text[] = "henri"; char *p; p = text; *(p + 1) = 'E'; // Output = hEnri // Now If we want to remove the "e" ie hnri, we would go for????? *(p + 1)=????? Please dont say start copying the array. I am looking for the best solution. Its an interview question... EDIT I specially mentioned the question that i am not asking for the solution like start moving the element. I thought there must be some other good solution..

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• Need help with displaying the message correctly in the pole display always starting at the beginning

  - by SA

  Hi, I am using an HP RS232 pole display with the following setting: Char type: USA/Europe (default) Command mode: EPSON (default) Baud rate: 9600, n , 8, 1 (default?) Passthru None (Default) Here's the code using System.IO.Ports; private SerialPort port; port = new SerialPort("COM2", 9600, Parity.None, 8, StopBits.One); port.Handshake = Handshake.None; Port.WriteLine("Welocome to something something"); It has 2 lines consisting of 20 characters each with a total of 40 characters. I have no control how and where the characters get displayed. I would like it to always begin on line 1 position 1 but as I said earlier how would I be able to do that. The same program if I run again and again it moves a character to the left. I have set it to accept ASCII char set and so I am able to type as is visble in the Writeline message

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• delete & new in c++

  - by singh

  Hi This may be very simple question,But please help me. i wanted to know what exactly happens when i call new & delete , For example in below code char * ptr=new char [10]; delete [] ptr; call to new returns me memory address. Does it allocate exact 10 bytes on heap, Where information about size is stored.When i call delete on same pointer,i see in debugger that there are a lot of byte get changed before and after the 10 Bytes. Is there any header for each new which contain information about number of byte allocated by new. Thanks a lot

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• Dereferencing deleted pointers always result in an Access Violation ??

  - by m3rLinEz

  I have a very simple C++ code here: char *s = new char[100]; strcpy(s, "HELLO"); delete [] s; int n = strlen(s); If I run this code from Visual C++ 2008 by pressing F5 (Start Debugging,) this always result in crash (Access Violation.) However, starting this executable outside the IDE, or using the IDE's Ctrl+F5 (Start without Debugging) doesn't result in any crash. What could be the difference? I also want to know if it's possible to stably reproduce the Access Violation crash caused from accessing deleted area? Is this kind of crash rare in real-life?

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• please help please

  - by davit-datuashvili

  http://stackoverflow.com/questions/2836934/how-to-compare-two-char-variables please show me a few steps how to start to write this code please

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• Why this works (Templates, SFINAE). C++

  - by atch

  Hi guys, reffering to yesterday's post, this woke me up this morning. Why this actually works? As long as the fnc test is concerned this fnc has no body so how can perform anything? Why and how this works? I'm REALLY interested to see your answers. template<typename T> class IsClassT { private: typedef char One; typedef struct { char a[2]; } Two; template<typename C> static One test(int C::*); //NO BODY HERE template<typename C> static Two test(…); //NOR HERE public: enum { Yes = sizeof(IsClassT<T>::test<T>(0)) == 1 }; enum { No = !Yes }; }; Thanks in advance with help to understand this very interesting fenomena.

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• Best way to implement a data structure in PHP ?

  - by Double Gras

  Hi, I want to use some kind of data structure in PHP (5.2), mainly in order to not pollute the global namespace. I think about two approaches, using an array or a class. Could you tell me which approach is better ? Thanks $SQL_PARAMETERS = array ( 'server' => '127.0.0.1', 'login' => 'root'); class SqlParameters { const SERVER = '127.0.0.1'; const LOGIN = 'root'; } echo $SQL_PARAMETERS['server']; echo SqlParameters::SERVER;

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• int[] to string c#

  - by Robin Webdev

  Hi I'm developing an client application in C# and the server is written in c++ the server uses: inline void StrToInts(int *pInts, int Num, const char *pStr) { int Index = 0; while(Num) { char aBuf[4] = {0,0,0,0}; for(int c = 0; c < 4 && pStr[Index]; c++, Index++) aBuf[c] = pStr[Index]; *pInts = ((aBuf[0]+128)<<24)|((aBuf[1]+128)<<16)|((aBuf[2]+128)<<8)|(aBuf[3]+128); pInts++; Num--; } // null terminate pInts[-1] &= 0xffffff00; } to convert an string to int[] in my c# client i recieve: int[4] { -14240, -12938, -16988, -8832 } How do I convert the array back to an string? I don't want to use unsafe code (e.g. pointers) Any of my tries resulted in unreadable strings.

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• Using pipes inside a class in C++

  - by Paul

  I'm trying to use this tutorial to make plots with Gnuplot in C++. However I will be using the pipe to Gnuplot from within a class, but then I run into some problems: I've got a header file where I declare all variables etc. I need to declare the pipe-variable here too, but how do I do that? I've tried doing it straight away, but it doesn't work: Logger.h: class Logger { FILE pipe; } Logger.cpp: Logger::Logger() { //Constructor *pipe = popen("gnuplot -persist","w"); } Gives the error Logger.cpp:28: error: no match for ‘operator=’ in ‘*((Logger*)this)->Logger::pipe = popen(((const char*)"gnuplot -persist"), ((const char*)"w"))’ Suggestions?

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• Does C++ require a destructor call for each placement new?

  - by Josh Haberman

  I understand that placement new calls are usually matched with explicit calls to the destructor. My question is: if I have no need for a destructor (no code to put there, and no member variables that have destructors) can I safely skip the explicit destructor call? Here is my use case: I want to write C++ bindings for a C API. In the C API many objects are accessible only by pointer. Instead of creating a wrapper object that contains a single pointer (which is wasteful and semantically confusing). I want to use placement new to construct an object at the address of the C object. The C++ object will do nothing in its constructor or destructor, and its methods will do nothing but delegate to the C methods. The C++ object will contain no virtual methods. I have two parts to this question. Is there any reason why this idea will not work in practice on any production compiler? Does this technically violate the C++ language spec?

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• Is it good practice to initialize array in C/C++?

  - by sand

  I recently encountered a case where I need to compare two files (golden and expected) for verification of test results and even though the data written to both the files were same, the files does not match. On further investigation, I found that there is a structure which contains some integers and a char array of 64 bytes, and not all the bytes of char array were getting used in most of the cases and unused fields from the array contain random data and that was causing the mismatch. This brought me ask the question whether it is good practice to initialize the array in C/C++ as well, as it is done in Java?

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• Why isn't my IO executed in order?

  - by HaskellElephant

  Hi, I'm having some fun learning about the haskell IO. However in my recent exploration of it I have encountered some problems with IO not executing in order, even inside a do construct. In the following code I am just keeping track of what cards are left, where the card is a tuple of chars (one for suit and one for value) then the user is continously asked for wich cards have been played. I want the putStr to be executed between each input, and not at the very end like it is now. module Main where main = doLoop cards doLoop xs = do putStr $ show xs s <- getChar n <- getChar doLoop $ remove (s,n) xs suits = "SCDH" vals = "A23456789JQK" cards = [(s,n) | s <- suits, n <- vals] type Card = (Char,Char) remove :: Card -> [Card] -> [Card] remove card xs = filter (/= card) xs

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• C String input confusion

  - by ahref

  C really isn't my strong point and after reading 3 chapters of a book on the subject and spending ages trying to get stuff working it just doesn't: #include <stdio.h> char *a,*b; int main( ) { char input[10]; fgets(input,sizeof input, stdin); a = input; fgets(input,sizeof input, stdin); b = input; printf("%s : %s",a,b); } I've isolated the problem from my main project. This code is meant to read in two strings and then print them however it seems to be setting a and b to point to input. Sample output from this code when A and B are entered is(don't worry about the \n's i can remove them): A B B : B How do i store the value of input in another variable eg. a or b so that in the above case A B A : B Is output? Thanks

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• not working function with no errors

  - by aya

  hello.. I've implemented a function to display an avl tree after inserting nodes into it like this template void AVLtree::display() const { display(Proot); } template void AVLtree::display(Node * ptr) const { if(ptr==0) return ; cout<value<<" "; display(ptr-Pleft); display(ptr-Pright); } after compiling,there were no errors ,the program worked but nothing were printed on the screen help me please....!! thanks

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• How would I implement code in a .h file into the main.cpp file?

  - by Lea

  I have a c++ project I am working on. I am a little stumped at the moment. I need a little help. I need to implement code from the .h file into the main.cpp file and I am not sure how to do that. For example code code from main.cpp: switch (choice){ case 1: // open an account { cout << "Please enter the opening balence: $ "; cin >> openBal; cout << endl; cout << "Please enter the account number: "; cin >> accountNum; cout << endl; break; } case 2:// check an account { cout << "Please enter the account number: "; cin >> accountNum; cout << endl; break; } and code from the .h file: void display(ostream& out) const; // displays every item in this list through out bool retrieve(elemType& item) const; // retrieves item from this list // returns true if item is present in this list and // element in this list is copied to item // false otherwise // transformers void insert(const elemType& item); // inserts item into this list // preconditions: list is not full and // item not present in this list // postcondition: item is in this list In the .h file you would need to use the void insert under transformer in the main.cpp under case 1. How would you do that? Any help is apprecaited. I hope I didn't confuse anyone on what I am needing to know how to do. Thanks

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• Can I control the mouse cursor from within R?

  - by Bernd Meyer

  Is it possible, to control the mouse pointer from the R console? I have something like this in mind: move_mouse(x_pos=100,y_pos=200) # move the mouse pointer to position (100,200) mouse_left_button_down # simulate a press of the left button move_mouse(x_pos=120,y_pos=250) # move mouse to select something mose_release_left_button # release the pressed button In MATLAB, something like this is possible with the following code import java.awt.Robot; mouse = Robot; mouse.mouseMove(0, 0); mouse.mouseMove(100, 200); Is something similar possible for the keybord? E.g. simulate keybord events?

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• strcat() won't exit

  - by Tristan Sebens

  I'm trying to implement a very basic server in C, one part of which is constructing HTTP headers. To do this I have written a class called header_builder, which basically constructs the headers for me. One of the most basic methods of this class is append_header_line, shown below: void append_header_line( const char *line, char *hdr ) { printf("Adding header line\n"); strcat( hdr, line ); printf("Line added. Adding ending.\n"); strcat( hdr, "\r\n" ); printf("Success\n"); } All it's supposed to do is tack the "line" parameter onto the end of the "hdr" parameter, and then add "\r\n" to the end of it all. The problem is that the first strcat call never exits. When I run this code, all it does is say: Adding header line Which means that the following lines never execute, and I can't figure out why. Any thoughts?

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• how to send Zip(binary) file Through HTTP post method in mFC/C++?

  - by Mahantesh

  I am posting the file to server and its working fine, But the my code fails when i try to post the .zip file. May be my code is wrong in the reading the zip file contents data. ifstream::pos_type size; char * memblock; ifstream file ("example.zip", ios::in|ios::binary|ios::ate); if (file.is_open()) { size = file.tellg(); memblock = new char [size]; file.seekg (0, ios::beg); file.read (memblock, size); file.close(); postBody.AppendFormat("Content-Disposition: form-data; name=\"datafile\"; filename=\"%s\"; \r\n\n%s", zipFilePath, memblock); postBody.AppendFormat("\r\n--%s--\r\n", boundary); }

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• How do I get characters common to two 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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