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• why it is up to the compiler to decide what value to assign when assigning an out-of-range value to

  - by Allopen

  in C++ Primer 4th edition 2.1.1, it says "when assigning an out-of-range value to a signed type, it is up to the compiler to decide what value to assign". I can't understand it. I mean, if you have code like "char 5 = 299", certainly the compiler will generate asm code like "mov BYTE PTR _sc$[ebp], 43"(VC) or "movb $43, -2(%ebp)"(gcc+mingw), it IS decided by the compiler. but what if we assign a value that is given by the user input? like, via command line? and the asm code generated will be "movb %al, -1(%ebp)"(gcc+mingw) and " mov cl, BYTE PTR _i$[ebp] mov BYTE PTR _sc$[ebp], cl "(VC), so now how can compiler decide what will happen? I think now it is decided by the CPU. Can you give me a clear explanation?

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• c++ malloc segmentation fault

  - by chnet

  I have a problem about malloc(). It is weird. My code is in the following. I use random generator to generate elements for an array. The array is opened by malloc(). If the array size is smaller than 8192, it is OK. If the size is larger than 8192, it shows segment fault. void random_generator(int num, int * array) { srand((unsigned)time(0)); int random_integer; for(int index=0; index< num; index++){ random_integer = (rand()%10000)+1; *(array+index) = random_integer; cout << index << endl; } } int main() { int array_size = 10000; int *input_array; input_array = (int*) malloc((array_size)); random_generator(8192, input_array); // if the number is larger than 8192, segment fault free(input_array); }

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• Passing arguments to Shared Function - C

  - by SpyrosR

  I have used dlopen to load an object and dlsym to get a function pointer to a shared object function. Everything works fine. I have tested it calling then the shared function which (for now) only prints and it works-prints fine in the main program calling it. Now I want to pass two arguments to this function. An int and a char * .Can anyone help me understand how can I pass arguments to a shared function? I have searched in the web but I cannot understand how it works.

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• Is `auto int i` valid C++0x?

  - by Motti

  In answering this question the question arose as to whether the traditional C meaning of the keyword auto (automatic storage) is still valid in C++0x now that it means type deduction. I remember that the old meaning of auto should remain where relevant but others disagreed. auto char c = 42; // either compilation error or c = '*' Looking at compilers I see the current division. Old meaning of auto is no longer allowed VS10 g++ Old meaning of auto is used where relevant Comeau Do you know which is the correct behaviour?

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• MySQLi String comparisons using keys

  - by asdasd

  I have a table with lets say 2 columns. id number, and value. Value is a string (var char). Lets say i have a number x, and a list of numbers a1, a2, a3, a4, a5..... where x is not in the list. All of these numbers correspond to a unique row in the table. I want to know if the string value for x in the table is contained in one of the string values for any table entry for a1, a2, a3, a4... Lets say i have these rows: x, aaa a1, bbb a2, ccc a3, ddd a4, aaabbbcc then i want somehow a confirmation that yes, the value for x is included in one of the values in my list of numbers (a4 contains x). I know i can do this in a couple queries and shove it down some PHP and get my answer. But can i do this with one query?

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• SQL tables using VARCHAR with UTF8 (with respect to multi byte character length)

  - by Elius

  Like in Oracle VARCHAR( 60 CHAR ) I would like to specify a varchar field with variable length depending on the inserted characters. for example: create table X (text varchar(3)) insert into X (text) VALUES ('äöü') Should be possible (with UTF8 as the default charset of the database). On DB2 I got this Error: DB2 SQL Error: SQLCODE=-302, SQLSTATE=22001 (Character data, right truncation occurred; for example, an update or insert value is a string that is too long for the column, or a datetime value cannot be assigned to a host variable, because it is too small.) I'm looking for solutions for DB2, MsSql, MySql, Hypersonic.

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• Excel VBA : Changing string in cells

  - by user1265125

  I have cells with data like these: ABCD123XYZ MPOP345MLU . . . . What I want to do is, to remove the 3rd and 4th character from all these cells, hence giving AB123XYZ MP345MLU How do I do this in VBA? I have no idea about this language, and if someone can guide me in the right direction, it'd be great :) I understand I have to: 1. Declare 2 string variables st1 and st2 2. Store data from cell A1 into the variable st1 3. Copy all but the 2nd and 3rd char into str2 4. Output Str2 into B1 5. Move to A2

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• How do I read long lines from a text file in C++?

  - by sonofdelphi

  I am using the following code for reading lines from a text-file. What is the best method for handling the case where the line is greater than the limit SIZE_MAX_LINE? void TextFileReader::read(string inFilename) { ifstream xInFile(inFilename.c_str()); if(!xInFile){ return; } char acLine[SIZE_MAX_LINE + 1]; while(xInFile){ xInFile.getline(acLine, SIZE_MAX_LINE); if(xInFile){ m_sStream.append(acLine); //Appending read line to string } } xInFile.close(); }

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• How do I declare and initialize a 2d int vector in C++?

  - by FrankTheTank

  I'm trying to do something like: #include <iostream> #include <vector> #include <ctime> class Clickomania { public: Clickomania(); std::vector<std::vector<int> > board; bool move(int, int); bool isSolved(); void print(); void pushDown(); }; Clickomania::Clickomania() : board(12, std::vector<int>(8,0)) { srand((unsigned)time(0)); for(int i = 0; i < 12; i++) { for(int j = 0; j < 8; j++) { int color = (rand() % 6) + 1; board[i][j] = color; } } } However, apparently I can't initialize the "board" vector of vectors this way. How can I create a public member of a 2d vector type and initialize it properly?

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• [C] Read line from file without knowing the line length.

  - by ryyst

  Hi, I want to read in a file line by line, without knowing the line length before. Here's what I got so far: int ch = getc(file); int length = 0; char buffer[4095]; while (ch != '\n' && ch != EOF) { ch = getc(file); buffer[length] = ch; length++; } printf("Line length: %d characters.", length); I can now figure out the line length, but only for lines that are shorter than 4095 characters. Is there a better way to do this (I already used fgets() but got told it wasn't the best way)? --Ry

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• Printing escape character

  - by danutenshu

  When I am given "d""\"/""b", I need to print out the statement character for character. (d, b, a slash, a backslash, and 5 quotes) in C++. The only errors that show now are the lines if(i.at(j)="\\") and else if(i.at(j)="\""). Also, how should the outside double apostrophes be excluded? #include <iostream> #include <cstdlib> using namespace std; int main (int argc, const char* argv[] ) { string i= argv[1]; for (int j=0; j>=sizeof(i)-1; j++) { if(i.at(j)="\\") { cout << "\\"; } else if(i.at(j)="\"") { cout << "\""; } else { cout << i.at(j); } } return 0; }

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• Delete on a very deep tree

  - by Kathoz

  I am building a suffix trie (unfortunately, no time to properly implement a suffix tree) for a 10 character set. The strings I wish to parse are going to be rather long (up to 1M characters). The tree is constructed without any problems, however, I run into some when I try to free the memory after being done with it. In particularly, if I set up my constructor and destructor to be as such (where CNode.child is a pointer to an array of 10 pointers to other CNodes, and count is a simple unsigned int): CNode::CNode(){ count = 0; child = new CNode* [10]; memset(child, 0, sizeof(CNode*) * 10); } CNode::~CNode(){ for (int i=0; i<10; i++) delete child[i]; } I get a stack overflow when trying to delete the root node. I might be wrong, but I am fairly certain that this is due to too many destructor calls (each destructor calls up to 10 other destructors). I know this is suboptimal both space, and time-wise, however, this is supposed to be a quick-and-dirty solution to a the repeated substring problem. tl;dr: how would one go about freeing the memory occupied by a very deep tree? Thank you for your time.

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• remove versioning on boost xml serialization

  - by cppanda

  hi, i just can't find a way to remove the version tracking from the boost xmlarchives. example <Settings class_id="0" tracking_level="0" version="1"> <px class_id="1" tracking_level="1" version="0" object_id="_0"> <TestInt>3</TestInt> <Resolution class_id="2" tracking_level="0" version="0"> <x>800</x> <y>600</y> </Resolution> <SomeStuff>0</SomeStuff> </px> </Settings> I want to get ride of the class_id="0" tracking_level="0" version="1" stuff, because for in this case i just don't need it and want a simple clean config like file code void serialize(Archive & ar, const unsigned int version) { ar & make_nvp("TestInt", TestInt); ar & make_nvp("Resolution", resolution); ar & make_nvp("SomeStuff", SomeStuff); } i found boost::serialization::track_never, but nowhere to use it

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• [C] How I change a variable of a type to another one?

  - by drigoSkalWalker

  I want to do it: int main () { bla bla bla void *onetype; switch (USER_INPUT_TYPE) { CASE CONVERT_TO_CHAR: convert onetype VOID TO CHAR HOW??? CASE CONVERT_TO_INT: convert onetype VOID TO INT HOW??? LOT OF CASES... } } Yes, I know type casting, but type casting is a 'temporary' change... So...Is there any way to accomplish it in C? EDIT : Stop stop stop! Please, see, what are you doing is type casting, I KNOW THIS, you are creating another variable of the desirable type like int i = (int) onetype, I don't want this, I want something else like onetype = (int) onetype, without recreate them, without allocate another variable. Thanks a lot guys!

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• Oracle spatial search within distance

  - by KA_lin

  I have the following table Cities: ID(int),City(char),latitude(float),longitude(float). Now based on a user`s longitude(ex:44.8) and latitude(ex:46.3) I want to search for all the cities near him within 100 miles/KM. I have found some examples but don`t know how to adapt them to my case select * from GEO.Cities a where SDO_WITHIN_DISTANCE([I don`t know], MDSYS.SDO_GEOMETRY(2001, 8307, MDSYS.SDO_POINT_TYPE(44.8,46.3, NULL) ,NULL, NULL), 'distance = 1000') = 'TRUE'; Any help would be appreciated. P.S: If it is possible to have the distance and to be sorted P.P.S: I want to do it in this way due to performance issues, I have done this in this way http://www.scribd.com/doc/2569355/Geo-Distance-Search-with-MySQL but it takes too long...

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• C input loop for shell

  - by AustinM

  So I'm working on creating a very simple C program that just preforms shell commands. This is what I have so far: #include <stdio.h> int main() { char input[30]; fputs("$ ", stdout); fflush(stdout); fgets(input, sizeof input, stdin); system(input); } It works, but only for one command. For example if I compile and type ./cmd I get the $ prompt. If I type ls I get what I'm supposed to get. But then it exits and goes back to the regular system shell. How can I make it so after the user types a command it goes back to the "$" input.

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• Understanding c++ block of code

  - by kotoko

  I was given a c++ main and have to code it so it works. I am having some trouble understanding the code as I am a bit new to cpp. Here is the code int main(int argc, char *argv[]) { Class::setAtribute("string"); Class(Class::CONSTANT) << "starting up..."; } Some questions: How can the first line work with no variables? Is it static? The second line is really strange for me, what I can make out is a Constructor that takes in a class constante and then prints it out somehow? If someone could explain me this bit of code it would be great! Thanks in advance.

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• C - add elements to struct by define

  - by CodeStepper

  I have a problem. I'm trying to add struct elements by previously defined constant. This is sample code (OpenGL+WinAPI) #define ENGINE_STRUCT \ HGLRC RenderingContext;\ HDC DeviceContext; And then: typedef struct SWINDOW { ENGINE_STRUCT HWND Handle; HINSTANCE Instance; CHAR* ClassName; BOOL Fullscreen; BOOL Active; MSG Message; } WINDOW; Is this possible? Thanks in advance.

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• How do I get the size of the boost buffer

  - by Anonymous

  I am trying to make an asynchronised server in visual studio and I use boost::asio::async_read(m_socket, boost::asio::buffer(m_buffer), boost::bind(&tcp_connection::handle_read, shared_from_this(), boost::asio::placeholders::error)); to get the buffer to be put in m_buffer boost::array<char, 256> m_buffer; but how do I get the size of this thing, m_buffer? size() didn't work, end() didn't work.. Any help would be fantastic. Thanks in advance.

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• Iterating through std queue

  - by Ockonal

  Hi, I'm trying to use BOOST_FOREACH for iterating through the std::queue. But there isn't iterators in that class cause I have an error: std::queue<std::string> someList; BOOST_FOREACH(std::string temp, someList) { std::cout << temp; } >no matching function for call to begin(...) >no type named ‘iterator’ in ‘class std::queue<std::basic_string<char> >’ I need in structure like: the first comes, the first goes away.

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• How to check whether iterators form a contiguous memory zone?

  - by Vincent

  I currently have the following function to read an array or a vector of raw data (_readStream is a std::ifstream) : template<typename IteratorType> inline bool MyClass::readRawData( const IteratorType& first, const IteratorType& last, typename std::iterator_traits<IteratorType>::iterator_category* = nullptr ) { _readStream.read(reinterpret_cast<char*>(&*first), (last-first)*sizeof(*first)); return _readStream.good(); } First question : does this function seem ok for you ? As we read directly a block of memory, it will only work if the memory block from first to last is contiguous in memory. How to check that ?

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• Programmatically check whether a linux kernel module exists or not at runtime

  - by dgraziotin

  I am writing a C daemon, which depends on the existence of two kernel modules in order to do its job. The program does not directly use these (or any other) modules. It only needs them to exist. Therefore, I would like to programmatically check whether these modules are already loaded or not, in order to warn the user at runtime. Before I start to do things like parsing /proc/modules or lsmod output, does a utility function already exist somewhere? Something like is_module_loaded(const char* name); I am pretty sure this has been asked before. However, I think I am missing the correct terms to search for this. Thanks!

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• C++ toLowerCase Function won't work - Access violation

  - by misaizdaleka

  Hi, I have a simple function which takes an array of characters as an argument, and converts all the characters to lower case. However, I get a weird access violation error. Here's the code: void toLower(char *rec) { int i=0; while (rec[i]!='\0') { if (rec[i]>='A' && rec[i]<='Z') rec[i]='a'+rec[i]-'A'; //this is where I get an error - assigning the //the value to rec[i] is the problem i++; } } Can you tell me what's my mistake? Thanks

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• C++: use array of strings wrapped in namespace?

  - by John D.

  I got the following code, wishing to wrap a group of strings nicely in a namespace: namespace msgs { const int arr_sz = 3; const char *msg[arr_sz] = {"blank", "blank", "blank" }; msg[0] = "Welcome, lets start by getting a little info from you!\n"; msg[1] = "Alright, bla bla bla.."; msg[2] = "etc."; } The code inside works nicely inside a function, but I don't know how to return an array from it. The namespace idea LOOKS fine, but it returns on the last three lines: error: expected constructor, destructor, or type conversion before ‘=’ token Why can't I define the array inside a namespace, do I need to do something first? It's nice because I can call it like printf(msgs::msg[1]) etc. I want to do this I just can't wrap my head around what's wrong :(

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• How do I get the inner arrays length in a 2d array in C#?

  - by Phukab

  Lets say I create a jagged 2d array like so: public static char[,] phoneLetterMapping = { {'0'}, {'1'}, {'A', 'B', 'C'} }; Now, given the first index of the array, I would like to be able to get the length of the inner array. So, I would like to be able to do something like: phoneLetterMapping[2].length I can do that in Java. But the intellisense menu doesn't return the normal members of an array when I type in the first bracket of the [][] 2d array. So, how do I get the inner array lengths in my 2d array in C#?

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