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  • C++ beginner question regarding chars

    - by Samwhoo
    I'm just messing around with some C++ at the moment trying to make a simple tic-tac-toe game and I'm running into a bit of a problem. This is my code: #include <iostream> using namespace std; class Square { public: char getState() const; void setState(char); Square(); ~Square(); private: char * pState; }; class Board { public: Board(); ~Board(); void printBoard() const; Square getSquare(short x, short y) const; private: Square board[3][3]; }; int main() { Board board; board.getSquare(1,2).setState('1'); board.printBoard(); return 0; } Square::Square() { pState = new char; *pState = ' '; } Square::~Square() { delete pState; } char Square::getState() const { return *pState; } void Square::setState(char set) { *pState = set; } Board::~Board() { } Board::Board() { } void Board::printBoard() const { for (int x = 0; x < 3; x++) { cout << "|"; for (int y = 0; y < 3; y++) { cout << board[x][y].getState(); } cout << "|" << endl; } } Square Board::getSquare(short x, short y) const { return board[x][y]; } Forgive me if there are blatantly obvious problems with it or it's stupidly written, this is my first program in C++ :p However, the problem is that when I try and set the square 1,2 to the char '1', it doesn't print out as a 1, it prints out as some strange character I didn't recognise. Can anyone tell me why? :) Thanks in advance.

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  • Create an Action<T> to "set" a property, when I am provided with the LINQ Expression for the "get"

    - by Alex
    I'd like to be able to generate a compiled expression to set a property, given the lambda expression that provides the "get" method for a property. Here's what I'm looking for: public Action<int> CreateSetter<T>(Expression<Func<T, int>> getter) { // returns a compiled action using the details of the getter expression tree, or null // if the write property is not defined. } I'm still trying to understand the various types of Expression classes, so if you can point me in the right direction that would be great.

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  • Efficient retrieval of lists over WebServices

    - by Chris
    I have a WCF WebService that uses LINQ and EF to connect to an SQL database. I have an ASP.NET MVC front end that collects its data from the webservice. It currently has functions such as List<Customer> GetCustomers(); As the number of customers increases massively the amount of data being passed increases also reducing efficiency. What is the best way to "page data" across WebServices etc. My current idea is to implement a crude paging system such as List<Customer> GetCustomers(int start, int length); This, however, means I would have to replicate such code for all functions returning List types. It is unfortunate that I cannot use LINQ as it would be much nicer. Does anyone have any advice or ideas of patterns to implement that would be "as nice as possible" Thanks

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  • Embarassing C++ question regarding const

    - by Neil Butterworth
    My comments on this answer got me thinking about the issues of constness and sorting. I played around a bit and reduced my issues to the fact that this code: #include <vector> int main() { std::vector <const int> v; } will not compile - you can't create a vector of const ints. I suppose I should have known this, but I've never needed to create such a thing before. However, it seems like a useful construct to me, and I wonder if there is any way round this problem - I want to add things to a vector (or whatever), but they should not be changed once added. There's probably some embarrassingly simple solution to this, but it's something I'd never considered before.

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  • networkstream always empty!

    - by ALEX
    hey I'm writing on an Server-Client program but when my client sends something, it never reaches my server! I'm sending like this: public void Send(string s) { char[] chars = s.ToCharArray(); byte[] bytes = chars.CharToByte(); nstream.Write(bytes, 0, bytes.Length); nstream.Flush(); } and Receiving in a background thread like this void CheckIncoming(object dd) { RecievedDelegate d = (RecievedDelegate)dd; try { while (true) { List<byte> bytelist = new List<byte>(); System.Threading.Thread.Sleep(1000); int ssss; ssss = nstream.ReadByte(); if (ssss > 1) { System.Diagnostics.Debugger.Break(); } if (bytelist.Count != 0) { d.Invoke(bytelist.ToArray()); } } } catch (Exception exp) { MSGBOX("ERROR:\n" + exp.Message); } } the ssss int is never 1 whats happening here???

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  • How to change a particular element of a C++ STL vector

    - by cambr
    vector<int> l; for(int i=1;i<=10;i++){ l.push_back(i); } Now, for example, how do I change the 5th element of the vector to -1? I tried l.assign(4, -1); It is not behaving as expected. None of the other vector methods seem to fit. I have used vector as I need random access functionality in my code (using l.at(i)).

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  • struts annotation issue

    - by Gourav
    My issue is that i have an annotation in Struts2 action class like private String[] origfilenofrom; @FieldExpressionValidator(fieldName="origfilenofrom",key="",message="File Length should be 12 for old file format and 15 for new file format",expression="checkorigFileFormat(origfilenofrom)") now my mehtod is public boolean checkorigFileFormat(String[] files ) { for(int counter=0;counter<files.length;counter++) { int n=files[counter].length(); if(!(n==12 || n==15)) { return false; } } return true; } So for any string in that string [], which is returning false the value is bei false. No matter 3 strings in that string [] are true if one is false then the annotaion message is displayed for all. I want the message not to display where the string is true. Help please

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  • Determine an object's class returned by a factory method (Error: function does not take 1 arguments

    - by tzippy
    I have a factorymethod that either returns an object of baseclass or one that is of derivedclass (a derived class of baseclass). The derived class has a method virtual void foo(int x) that takes one argument. baseclass however has virtual void foo() without an argument. In my code, a factory method returns a pointer of type bar that definetly points to an object of class derivedclass. However since this is only known at runtime I get a compiler error saying that foo() does not take an argument. Can I cast this pointer to a pointer of type derivedclass? std::auto_ptr<baseclass> bar = classfactory::CreateBar(); //returns object of class derivedclass bar->foo(5); class baseclass { public: virtual void foo(); } class derivedclass : public baseclass { public: virtual void foo(int x); }

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  • Converting time period strings to value/unit pair

    - by randomtoor
    I need to parse the contents of a string that represents a time period. The format of the string is value/unit, e.g.: 1s, 60min, 24h. I would separate the actual value (an int) and unit (a str) to separated variables. At the moment I do it like this: def validate_time(time): binsize = time.strip() unit = re.sub('[0-9]','',binsize) if unit not in ['s','m','min','h','l']: print "Error: unit {0} is not valid".format(unit) sys.exit(2) tmp = re.sub('[^0-9]','',binsize) try: value = int(tmp) except ValueError: print "Error: {0} is not valid".format(time) sys.exit(2) return value,unit However, it is not ideal as things like 1m0 are also (wrongly) validated (value=10,unit=m). What is the best way to validate/parse this input?

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  • How to query for entities with no matching siblings, with LINQ?

    - by Ryan
    I've got the two following entities ... class Citation { public int CitationId { get; set; } public string Identifier { get; set; } } class CitationIdentifier { public int CitationIdentifierId { get; set; } public string Identifier { get; set; } } I'm trying to query for all Citation records where the Identifier property does not match any of the CitationIdentifiers record Identifier property. So, if I have a Citation with an Identifier property containing "foo", but there are no CitationIdentifier records with an Identifier property containing "foo", then I'd like to retrieve that Citation. I'm working with an IDbSet<Citation>. Any ideas? Thanks.

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  • C++ stringstream reads all zero's

    - by user69514
    I have a file which contains three integers per line. When I read the line I use a stringstream to separate the values, but it only reads the first value as it is. The other two are read as zero's. ifstream inputstream(filename.c_str()); if( inputstream.is_open() ){ string line; stringstream ss; while( getline(inputstream, line) ){ //check line and extract elements int id; double income; int members; ss.clear(); ss.str(line); ss >> id >> income >> members; In the case above, id is extracted correctly, but income, and members get assigned zero instead of the actual value.

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  • Why can't I reserve 1,000,000,000 in my vector ?

    - by vipersnake005
    When I type in the foll. code, I get the output as 1073741823. #include <iostream> #include <vector> using namespace std; int main() { vector <int> v; cout<<v.max_size(); return 0; } However when I try to resize the vector to 1,000,000,000, by v.resize(1000000000); the program stops executing. How can I enable the program to allocate the required memory, when it seems that it should be able to? I am using MinGW in Windows 7. I have 2 GB RAM. Should it not be possible? In case it is not possible, can't I declare it as an array of integers and get away? BUt even that doesn't work. Another thing is that, suppose I would use a file(which can easily handle so much data ). How can I let it read and write and the same time. Using fstream file("file.txt', ios::out | ios::in ); doesn't create a file, in the first place. But supposing the file exists, I am unable to use to do reading and writing simultaneously. WHat I mean is this : Let the contents of the file be 111111 Then if I run : - #include <fstream> #include <iostream> using namespace std; int main() { fstream file("file.txt",ios:in|ios::out); char x; while( file>>x) { file<<'0'; } return 0; } Shouldn't the file's contents now be 101010 ? Read one character and then overwrite the next one with 0 ? Or incase the entire contents were read at once into some buffer, should there not be atleast one 0 in the file ? 1111110 ? But the contents remain unaltered. Please explain. Thank you.

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  • Deserialize Xml with empty elements in C#

    - by user204086
    Trying to deserialize some xml snippits into objects. The problem is that I'm getting an invalid format on every empy element tag. I can deserialize the object no problem when all of the elements have values. Or the empty elements are ommitted. Xml Snippit: <foo><propOne>1</propOne><propTwo /></foo> C# Class: [Serialilbe()] public class foo { public foo(){} [XmlElementAttribute(IsNullable = true)] public int? propOne {get;set;} [XmlElementAttribute(IsNullable = true)] public int? propTwo {get;set;} } Is there a setting on the class I can make to adjust the parsing? or Is there an easy way I can apply xsl to remove these elements? or Should I use regEx to remove the empty elements be fore desrializing? or an even better way?

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  • How do I create an editable databound combo box in a DataGrid in WinForm

    - by signaldev235
    I have a noob question. I have a WinForm (.net 2.0 in VS 2008) on my from I have a DataGrid One of the fields in that datagrid is a combo box that is bound to a separate table. this works, but I am unable to edit or add, I cannot add a value that is not on the list. I am looking to create a lookup box for lack of a better term. The form is for Parts Order Entry In the data Grid Data Source is PartsOrder_table, the Work order Field is a int in the PartsOrder_table, and the combo box is bound to the WorkOrder_table. The WorkOPRder_Table has WorkOrd_ID int and WrkOrd nvarchar(10) the Combo Box Data Source is WorkOrd_Table Display Member is WorkOrd Value Member is WorkOrder_ID This works great with the problem that I cannot add or select anything not in WorkOrder_table. Any Help would be greatly appreciated. Thanks

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  • Histrogram matching - image processing - c/c++

    - by Raj
    Hello I have two histograms. int Hist1[10] = {1,4,3,5,2,5,4,6,3,2}; int Hist1[10] = {1,4,3,15,12,15,4,6,3,2}; Hist1's distribution is of type multi-modal; Hist2's distribution is of type uni-modal with single prominent peak. My questions are Is there any way that i could determine the type of distribution programmatically? How to quantify whether these two histograms are similar/dissimilar? Thanks

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  • C# A simple Hangman game

    - by Radostin Angelov
    I'm trying to create a simple Hangman game and i have gotten so far, to make it read all words from a text file, but I don't know how to make the code work for every single word. I have another project, working with 3/4 words but with repeating nested if statements. I want to make it as shorter as possible. This is the code i have so far : using System; using System.Linq; class Program { static void Main() { string[] words = System.IO.File.ReadAllLines(@"C:\Users\ADMIN\Desktop\Letters\Letters.txt"); int LengthOfArray = words.Length; Random rnd = new Random(); int random = rnd.Next(1, 3); char[] letters = words[random].ToCharArray(); bool WordIsHidden = true; char hiddenChar = '_'; char GuessedLetter = hiddenChar; var retry = true; while (retry = true) { Console.WriteLine(letters); letters = GuessedLetter.ToString().ToCharArray(); for (int i = 1; i <= LengthOfArray; i++) { Console.Write("{0} ", GuessedLetter); } Console.WriteLine("Enter a letter!"); char letter = char.Parse(Console.ReadLine()); if (words[random].Contains<char>(letter)) { WordIsHidden = false; GuessedLetter = letter; Console.Write(letters); } else { if (WordIsHidden == true) { Console.Write("You guessed wrong!"); } } } } } Also I'm trying to make the game show each letter, the user has guessed on it's corresponding position, but now the letter is one line higher than the rest of the word and it's not in it's right position. Edited: Here is the result : cat ___Enter a letter! a __ aaaEnter a letter! t aa tttEnter a letter! IF anyone have a clue for where does this come from and how can I fix it, any help will be greatly appreciated.

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  • Implement abstract class as a local class? pros and cons

    - by sinec
    Hi, for some reason I'm thinking on implementing interface within a some function(method) as local class. Consider following: class A{ public: virtual void MethodToOverride() = 0; }; A * GetPtrToAImplementation(){ class B : public A { public: B(){} ~B(){} void MethodToOverride() { //do something } }; return static_cast<A *>(new B()); } int _tmain(int argc, _TCHAR* argv[]) { A * aInst = GetPtrToAImplementation(); aInst->MethodToOverride(); delete aInst; return 0; } the reason why I'm doing this are: I'm lazy to implement class (B) in separate files MethodToOverride just delegates call to other class Class B shouldn't be visible to other users no need to worry about deleting aInst since smart pointers are used in real implementation So my question is if I'm doing this right? Thanks in advance!

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  • How to add values accordingly of the first indices of a dictionary of tuples of a list of strings? Python 3x

    - by TheStruggler
    I'm stuck on how to formulate this problem properly and the following is: What if we had the following values: {('A','B','C','D'):3, ('A','C','B','D'):2, ('B','D','C','A'):4, ('D','C','B','A'):3, ('C','B','A','D'):1, ('C','D','A','B'):1} When we sum up the first place values: [5,4,2,3] (5 people picked for A first, 4 people picked for B first, and so on like A = 5, B = 4, C = 2, D = 3) The maximum values for any alphabet is 5, which isn't a majority (5/14 is less than half), where 14 is the sum of total values. So we remove the alphabet with the fewest first place picks. Which in this case is C. I want to return a dictionary where {'A':5, 'B':4, 'C':2, 'D':3} without importing anything. This is my work: def popular(letter): '''(dict of {tuple of (str, str, str, str): int}) -> dict of {str:int} ''' my_dictionary = {} counter = 0 for (alphabet, picks) in letter.items(): if (alphabet[0]): my_dictionary[alphabet[0]] = picks else: my_dictionary[alphabet[0]] = counter return my_dictionary This returns duplicate of keys which I cannot get rid of. Thanks.

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  • MySQL: Query to obtain recipes using all given ingredients.

    - by John_A
    hi I have the following simplified tables: CREATE TABLE recipe(id int, name varchar(25)); CREATE TABLE ingredient(name varchar(25)); CREATE TABLE uses_ingredient(recipe_id int, name varchar(25)); I want to make a query that returns all id's of recipes that contain both Chicken and Cream. I have tried SELECT recipe_id FROM uses_ingredient INNER JOIN (SELECT * FROM ingredient WHERE name="Chicken" OR name="Cream") USING (name) GROUP BY recipe_id HAVING COUNT(recipe_id) >= (SELECT COUNT(*) FROM theme); which gives me :"ERROR 1248 (42000): Every derived table must have its own alias" and is probably wrong too. Next I tried SELECT recipe_id FROM (SELECT * FROM ingredient WHERE name="Chicken" OR name="Cream") AS t INNER JOIN uses_ingredient USING (name) GROUP BY recipe_id HAVING COUNT(recipe_id)>= (SELECT COUNT(*) FROM t); which gives "ERROR 1146 (42S02): Table 'recipedb.t' doesn't exist" I want to avoid creating temporary tables including using ENGINE=MEMORY.

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  • C pointer question, dereferencing crash

    - by skynorth
    Why do this work? int *var; while(scanf("%d", &var) && *var != 0) printf("%d \n", var); While this does not? int *var; while(scanf("%d", &var) && var != 0) printf("%d \n", var); Doesn't * (dereference operator) give you the value pointed by the pointer? So why does *var != 0 crash the program, while var != 0 does not?

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  • Does a CPU assigns a value atomically to memory?

    - by Poni
    Hi! A quick question I've been wondering about for some time; Does the CPU assign values atomically, or, is it bit by bit (say for example a 32bit integer). If it's bit by bit, could another thread accessing this exact location get a "part" of the to-be-assigned value? Think of this: I have two threads and one shared "unsigned int" variable (call it "g_uiVal"). Both threads loop. On is printing "g_uiVal" with printf("%u\n", g_uiVal). The second just increase this number. Will the printing thread ever print something that is totally not or part of "g_uiVal"'s value? In code: unsigned int g_uiVal; void thread_writer() { g_uiVal++; } void thread_reader() { while(1) printf("%u\n", g_uiVal); }

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  • When convert a void pointer to a specific type pointer, which casting symbol is better, static_cast or reinterpret_cast?

    - by BugCreater
    A beginner question with poor English: Here I got a void* param and want to cast(or change) it to a specific type. But I don't know which "casting symbol" to use. Either**static_cast** and reinterpret_cast works. I want to know which one is better? which one does the Standard C++ recommend? typedef struct { int a; }A, *PA; int foo(void* a) // the real type of a is A* { A* pA = static_cast<A*>(a); // or A* pA = reinterpret_cast<A*>(a);? cout<<pA->a<<endl; return 0; } Here I use A* pA = static_cast(a); or A* pA = reinterpret_cast(a); is more proper?

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  • Express one dimension of 2d array as new array

    - by user208080
    I have a 2d array a[3,3]. How can I express one dimension as a new array and pass it to some function? int[,] a = new int[3,3]; a[0,0] = 1; ... string b = concatenate(a[0]); // where concatenate is a function // take a one dimension array as param Also, can I create a 65000x65000 array with C#? I got some "out of memory" error.

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  • Calling C++ function from C.

    - by claws
    I know this. Calling C function from C++: If my application was in C++ and I had to call functions from a library written in C. Then I would have used //main.cpp extern "C" void C_library_function(int x, int y);//prototype C_library_function(2,4);// directly using it. This wouldn't mangle the name C_library_function and linker would find the same name in its input *.lib files and problem is solved. Calling C++ function from C??? But here I'm extending a large application which is written in C and I need to use a library which is written in C++. Name mangling of C++ is causing trouble here. Well I cannot use C++ compiler over my C project because thats breaking lot of other stuff. What is the way out? By the way I'm using MSVC

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