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  • setsockopt (sys/socket.h)

    - by lojin
    The prototype for setsockopt is: int setsockopt(int socket, int level, int option_name, const void *option_value, socklen_t option_len); Are the following all correct ? Which are not ? a.) int buffsize = 50000; setsockopt(s, SOL_SOCKET, SO_RCVBUF, (char *)&buffsize, sizeof(buffsize)); b.) int buffsize = 50000; setsockopt(s, SOL_SOCKET, SO_RCVBUF, (void *)&buffsize, sizeof(buffsize)); c.) char *buffsize = "50000"; setsockopt(s, SOL_SOCKET, SO_RCVBUF, buffsize, strlen(buffsize)); d.) setsockopt(s, SOL_SOCKET, SO_RCVBUF, "50000", 5);

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  • For-Each and Pointers in Java

    - by John
    Ok, so I'm tyring to iterate through an ArrayList and remove a specefic element. However, I am having some trouble using the For-Each like structure. When I run the following code: ArrayList<String> arr = new ArrayList<String>(); //... fill with some values (doesn't really matter) for(String t : arr) { t = " some other value "; //hoping this would change the actual array } for(String t : arr) { System.out.println(t); //however, I still get the same array here } My question in, how can I make 't' a pointer to 'arr' so that I am able to change the values in a for-each loop? I know I could loop through the ArrayList using a different structure, but this one looks so clean and readable, it would just be nice to be able to make 't' a pointer. All comments are appreciated! Even if you say I should just suck it up and use a different construct.

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  • Redirecting one file to another using dub2 and strtok

    - by Sergiy Zakharov
    OK, here goes. I have to write a program, in which I need to use strtok and dup2 to redirect one file to another, but I need to also have the user to actually put the command cat < file1 file2, but not from the shell, but instead by using my program. That's why I need strtok. And the reason my program doesn't work is probably because of that, because I don't really understand how strtok works. I found a similar program on the internet, but they just take the ls command and redirect it to the file. That's it. My program is much more complicated. I mean, it would've been easier just to say in shell cat < file1 file2, but for some reason they want us to do it this way. So, anyways, here is what I have so far (here I just combined what I have found on the internet with what I already had from before. We had to do something similar but then the user would just go ls or ls -l. Very simple stuff. This is much harder, for me, at least.) #include <fcntl.h> #include <unistd.h> #include <stdio.h> #include <errno.h> #include <sys/wait.h> #include <string.h> int main() { pid_t pid; char line[256]; char *args[129]; int i; int fd; int status; char *temp; while (1) { printf(">"); if (fgets(line, 256, stdin) == 0) { exit(0); } else { pid = fork(); if (pid == 0) { i = 0; temp = strtok("<",line); while (temp != NULL) { args[i++] = temp; temp = strtok(">",line); args[i] = '\0'; } fd = open("hello", O_RDONLY); dup2(fd, STDIN_FILENO); fd = open("world", O_WRONLY|O_CREAT|O_TRUNC, S_IRWXU); dup2(fd, STDOUT_FILENO ); close(fd); execvp(args[0], args); } else { close(fd); wait(&status); } } } } Any help would be greatly appreciated.

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  • Difference between debug and release.

    - by atch
    Why when I'm debugging in debug mode everything in code below works as suppose to but when I switch to release I'm getting strange result? void say_hello(int argc, char* argv[])//In release mode argc has different values from 124353625 to 36369852 <include iostream> { std::cout << "In say_hello()\n"; } int main(int argc, char* argv[]) { say_hello(3,argv);//when instead of literal I enter "argc" everything is ok. return 0; } Thanks for help.

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  • Floating point comparison in STL, BOOST

    - by Paul
    Is there in the STL or in Boost a set of generic simple comparison functions? The one I found are always requiring template parameters, and/or instantiation of a struct template. I'm looking for something with a syntax like : if ( is_greater(x,y) ) { ... } Which could be implemented as : template <typename T> bool is_greater(const T& x, const T& y) { return x > y + Precision<T>::eps; }

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  • Are pointers primitive types in C++?

    - by Space_C0wb0y
    I was wondering about the last constructor for std::string mentioned here. It says: template<class InputIterator> string (InputIterator begin, InputIterator end); If InputIterator is an integral type, behaves as the sixth constructor version (the one right above this) by typecasting begin and end to call it: string(static_cast<size_t>(begin),static_cast<char>(end)); In any other case, the parameters are taken as iterators, and the content is initialized with the values of the elements that go from the element referred by iterator begin to the element right before the one referred by iterator end. So what does that mean if InputIterator is a char * ?

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  • MinMax Heap implementation without an array

    - by user576531
    Hi. I found lots of MinMax Heap implementations, that were storing data in an array. It is realy easy to implement, that is way I am looking for something different. I want to create a MinMax Heap using only elements of the Heap with pointers to left child and right child (and afcourse a key to compare). So the Heap have only pointer to the root object (min level), and a root object have a pointer to his children (max level) and so on. I know how to insert a new object (finding a proper path by using binary represenation of int depending on Heap size), but I don't know how to implement the rest (push up (down) the element, find parent or grandparent). Thx for help

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  • std::map insert segmentation fault

    - by Jakub Czaplicki
    Why does this code stop with segmentation fault : class MapFile { public: /* ... */ std::map <unsigned int, unsigned int> inToOut; }; bool MapFile::LoadMapFile( const wxString& fileName ) { /* ... */ inToOut.insert( std::make_pair(input,output) ); } but this one works fine : class MapFile { public: /* ... */ }; bool MapFile::LoadMapFile( const wxString& fileName ) { /* ... */ std::map <unsigned int, unsigned int> inToOut; inToOut.insert( std::make_pair(input,output) ); } ?

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  • emacs: how do I use edebug on code that is defined in a macro?

    - by Cheeso
    I don't even know the proper terminology for this lisp syntax, so I don't know if the words I'm using to ask the question, make sense. But the question makes sense, I'm sure. So let me just show you. cc-mode (cc-fonts.el) has things called "matchers" which are bits of code that run to decide how to fontify a region of code. That sounds simple enough, but the matcher code is in a form I don't completely understand, with babckticks and comma-atsign and just comma and so on, and furthermore it is embedded in a c-lang-defcost, which itself is a macro. And I want to run edebug on that code. Look: (c-lang-defconst c-basic-matchers-after "Font lock matchers for various things that should be fontified after generic casts and declarations are fontified. Used on level 2 and higher." t `(;; Fontify the identifiers inside enum lists. (The enum type ;; name is handled by `c-simple-decl-matchers' or ;; `c-complex-decl-matchers' below. ,@(when (c-lang-const c-brace-id-list-kwds) `((,(c-make-font-lock-search-function (concat "\\<\\(" (c-make-keywords-re nil (c-lang-const c-brace-id-list-kwds)) "\\)\\>" ;; Disallow various common punctuation chars that can't come ;; before the '{' of the enum list, to avoid searching too far. "[^\]\[{}();,/#=]*" "{") '((c-font-lock-declarators limit t nil) (save-match-data (goto-char (match-end 0)) (c-put-char-property (1- (point)) 'c-type 'c-decl-id-start) (c-forward-syntactic-ws)) (goto-char (match-end 0))))))) I am reading up on lisp syntax to figure out what those things are and what to call them, but aside from that, how can I run edebug on the code that follows the comment that reads ;; Fontify the identifiers inside enum lists. ? I know how to run edebug on a defun - just invoke edebug-defun within the function's definition, and off I go. Is there a corresponding thing I need to do to edebug the cc-mode matcher code forms?

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  • win7 + vc7.1 + mfc = stackoverflow

    - by fogbit
    Hello! I've moved my vc7.1 project from WInXP to Win7. After rebuilding i got stackoverflow error in function _malloc_dbg when i start the program. "Unhandled exception at 0x0051bf0f in XXX.exe: 0xC00000FD: Stack overflow." Call stack: msvcr71d.dll!_malloc_dbg(unsigned int nSize=140, int nBlockUse=2, const char * szFileName=0x10267784, int nLine=163) msvcr71d.dll!_calloc_dbg(unsigned int nNum=1, unsigned int nSize=140, int nBlockUse=2, const char * szFileName=0x10267784, int nLine=163) msvcr71d.dll!_mtinit() msvcr71d.dll!_CRTDLL_INIT(void * hDllHandle=0x10200000, unsigned long dwReason=1, void * lpreserved=0x0018fd24) I tried to set up different stacksizes in project options (from 10 to 100 mbytes), in all cases i got this error. How can i fix this?

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  • C++: Can a macro expand "abc" into 'a', 'b', 'c'?

    - by Peter Alexander
    I've written a variadic template that accepts a variable number of char parameters, i.e. template <char... Chars> struct Foo; I was just wondering if there were any macro tricks that would allow me to instantiate this with syntax similar to the following: Foo<"abc"> or Foo<SOME_MACRO("abc")> or Foo<SOME_MACRO(abc)> etc. Basically, anything that stops you from having to write the characters individually, like so Foo<'a', 'b', 'c'> This isn't a big issue for me as it's just for a toy program, but I thought I'd ask anyway.

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  • C: using clock() to measure time in multi-threaded programs

    - by Shinka
    I've always used clock() to measure how much time my application took from start to finish, as; int main(int argc, char *argv[]) { const clock_t START = clock(); // ... const double T_ELAPSED = (double)(clock() - START) / CLOCKS_PER_SEC; } Since I've started using POSIX threads this seem to fail. It looks like clock() increases N times faster with N threads. As I don't know how many threads are going to be running simultaneously, this approach fails. So how can I measure how much time has passed ?

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  • C++ : size of int, long, etc...

    - by Jérôme
    I'm looking for detailed informations regarding the size of basic C++ types. I know that it depends on the architecture (16 bits, 32 bits, 64 bits) and the compiler. But are there any standards ? I'm using Visual Studio 2008 on a 32 bit achitecture. Here is what I get : char : 1 byte short : 2 bytes int : 4 bytes long : 4 bytes float : 4 bytes double : 8 bytes I tried to find, without much success, reliable informations telling the sizes of char, short, int , long, double, float (and other types I don't think of) under different architecture and compiler.

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  • Streaming multiple TObjects to a TMemoryStream

    - by Altar
    I need to store multiple objects (most of them are TObject/non persistent) to a TMemoryStream, save the stream to disk and load it back. The objects need to be streamed one after each other. Some kind of universal container. I started to make several functions that store stuff to stream - for example function StreamReadString(CONST MemStream: TMemoryStream): string; StreamWriteString(CONST MemStream: TMemoryStream; s: string); However, it seems that I need to rewrite a lot of code. One of the many examples is TStringList.LoadFromStream that will not work so it needs to be rewritten. This is because TStringList needs to be the last object in the stream (it reads from current position to the end of the stream). Anybody knows a library that provide basic functionality like this? I am using Delphi 7 so RTTI won't help too much.

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  • Why do i get segfault at the end of the application after everything's been done properly ?

    - by VaioIsBorn
    #include <string.h> #include <stdlib.h> #include <stdio.h> int main(void) { unsigned char *stole; unsigned char pass[] = "m4ak47"; printf("Vnesi password: \t"); scanf("%s", stole); if(strncmp(stole, pass, sizeof(pass)) != 0) { printf("wrong password!\n"); exit(0); } else printf("Password correct\n"); printf("some stuf here...\n\n"); return 0; } This program is working nice, but with one problem - if the password is correct then it DOES do the printing of 'some stuf here...' but it also shows me segmentation fault error at the end. Why ?

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  • Program crash for array copy with ifort

    - by Stefano Borini
    This program crashes with Illegal instruction: 4 on MacOSX Lion and ifort (IFORT) 12.1.0 20111011 program foo real, pointer :: a(:,:), b(:,:) allocate(a(5400, 5400)) allocate(b(5400, 3600)) a=1.0 b(:, 1:3600) = a(:, 1:3600) print *, a print *, b deallocate(a) deallocate(b) end program The same program works with gfortran. I don't see any problem. Any ideas ? Unrolling the copy and performing the explicit loop over the columns works in both compilers. Note that with allocatable instead of pointer I have no problems. The behavior is the same if the statement is either inside a module or not. I confirm the same behavior on Linux using ifort (IFORT) 12.1.3 20120130.

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  • some verd problems in qt

    - by prabhakaran
    I am very new to qt, So whatever I facing is either errors or problems. Here goes some of them, 1)Just try to install it in VisualStudio, you will got enough for the day. 2)After you installed it as a separate qt(without embedding it inside visual studio).Open a c++ file in qt, = then you won't get any option to compile it. 3)Create a empty qt4 project like below #include<iostream> using namespace std; int main(int a,char * argv[]) { } Then build it, you will get a error like this C:\qt-greenhouse\Trolltech\Code_less_create_more\Trolltech\Code_less_create_more\Troll\4.6\qt\src\winmain/qtmain_win.cpp:131: undefined reference to `qMain(int, char**)' Can anybody clear any of these problems to me.

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  • how to reloadData in tableView when tableview access data from database.

    - by Ajeet Kumar Yadav
    I am new in iphone i am developing a application that take value from data base and display data in tableview. in this application we save data from one data table to other data table this is when add first time work and when we do second time application is crash. how to solve this problem i am not understand code is given bellow my appdelegate code for insert value from one table to other is given bellow -(void)sopinglist { //////databaseName= @"SanjeevKapoor.sqlite"; databaseName =@"AjeetTest.sqlite"; NSArray *documentPaths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES); NSString *documentsDir = [documentPaths objectAtIndex:0]; databasePath =[documentsDir stringByAppendingPathComponent:databaseName]; [self checkAndCreateDatabase]; list1 = [[NSMutableArray alloc] init]; sqlite3 *database; if (sqlite3_open([databasePath UTF8String], &database) == SQLITE_OK) { if(addStmt == nil) { ///////////const char *sql = "insert into Dataa(item) Values(?)"; const char *sql = " insert into Slist select * from alootikki"; ///////////// const char *sql =" Update Slist ( Incredients, Recipename,foodtype) Values(?,?,?)"; if(sqlite3_prepare_v2(database, sql, -1, &addStmt, NULL) != SQLITE_OK) NSAssert1(0, @"Error while creating add statement. '%s'", sqlite3_errmsg(database)); } /////for( NSString * j in k) sqlite3_bind_text(addStmt, 1, [k UTF8String], -1, SQLITE_TRANSIENT); //sqlite3_bind_int(addStmt,1,i); // sqlite3_bind_text(addStmt, 1, [coffeeName UTF8String], -1, SQLITE_TRANSIENT); // sqlite3_bind_double(addStmt, 2, [price doubleValue]); if(SQLITE_DONE != sqlite3_step(addStmt)) NSAssert1(0, @"Error while inserting data. '%s'", sqlite3_errmsg(database)); else //SQLite provides a method to get the last primary key inserted by using sqlite3_last_insert_rowid coffeeID = sqlite3_last_insert_rowid(database); //Reset the add statement. sqlite3_reset(addStmt); // sqlite3_clear_bindings(detailStmt); //} } sqlite3_finalize(addStmt); addStmt = nil; sqlite3_close(database); } And the table View code for access data from database is given bellow SanjeevKapoorAppDelegate *appDelegate =(SanjeevKapoorAppDelegate *)[[UIApplication sharedApplication] delegate]; [appDelegate sopinglist]; ////[appDelegate recpies]; /// NSArray *a =[[appDelegate list1] componentsJoinedByString:@","]; k= [[appDelegate list1] componentsJoinedByString:@","];

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  • How to approach copying objects with smart pointers as class attributes?

    - by tomislav-maric
    From the boost library documentation I read this: Conceptually, smart pointers are seen as owning the object pointed to, and thus responsible for deletion of the object when it is no longer needed. I have a very simple problem: I want to use RAII for pointer attributes of a class that is Copyable and Assignable. The copy and assignment operations should be deep: every object should have its own copy of the actual data. Also, RTTI needs to be available for the attributes (their type may also be determined at runtime). Should I be searching for an implementation of a Copyable smart pointer (the data are small, so I don't need Copy on Write pointers), or do I delegate the copy operation to the copy constructors of my objects as shown in this answer? Which smart pointer do I choose for simple RAII of a class that is copyable and assignable? (I'm thinking that the unique_ptr with delegated copy/assignment operations to the class copy constructor and assignment operator would make a proper choice, but I am not sure) Here's a pseudocode for the problem using raw pointers, it's just a problem description, not a running C++ code: // Operation interface class ModelOperation { public: virtual void operate = (); }; // Implementation of an operation called Special class SpecialModelOperation : public ModelOperation { private: // Private attributes are present here in a real implementation. public: // Implement operation void operate () {}; }; // All operations conform to ModelOperation interface // These are possible operation names: // class MoreSpecialOperation; // class DifferentOperation; // Concrete model with different operations class MyModel { private: ModelOperation* firstOperation_; ModelOperation* secondOperation_; public: MyModel() : firstOperation_(0), secondOperation_(0) { // Forgetting about run-time type definition from input files here. firstOperation_ = new MoreSpecialOperation(); secondOperation_ = new DifferentOperation(); } void operate() { firstOperation_->operate(); secondOperation_->operate(); } ~MyModel() { delete firstOperation_; firstOperation_ = 0; delete secondOperation_; secondOperation_ = 0; } }; int main() { MyModel modelOne; // Some internal scope { // I want modelTwo to have its own set of copied, not referenced // operations, and at the same time I need RAII to work for it, // as soon as it goes out of scope. MyModel modelTwo (modelOne); } return 0; }

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  • Is this a correct implementation of singleton C++?

    - by Kamal
    class A{ static boost::shared_ptr<A> getInstance(){ if(pA==NULL){ pA = new A(); } return boost::shared_ptr(pA); } //destructor ~A(){ delete pA; pA=NULL; } private: A(){ //some initialization code } //private assigment and copy constructors A(A const& copy); // Not Implemented A& operator=(A const& copy); // Not Implemented static A* pA; }; A* A::pA = NULL;

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  • passin structure form VC++ to C#

    - by Anu
    Hi, im using C# dll in VC++ application.I have somedetails in VC++ like PageNumer pageTitle PageDesc BoxDetail I have to pass this to C# Dll. So i made one structure in VC++,then i pas that to C#.But i could't do that.Pls help mw. VC++ Function: struct SCS3OverVwPg { __int32 iOvrPgNo; char sOvrPgTitle[30]; //OverView Page Title }; void CToolTab::SendOverview() { SCS3OverVwPg *pOverVw = 0; pOverVw = new SCS3OverVwPg; Globals1::gwtoolbar->SetTree(pOverVw); } C# function: public struct SCS3Over { Int32 iOvrPgNo; char[] sOvrPgTitle; } public void SetTree(SCS3Over x) { MessageBox.Show("Data received"); } If i do like this,it shows error error C2664: 'Tabcontrol::ToolBar::SetTree' : cannot convert parameter 1 from 'SCS3OverVwPg *' to 'SCS3Over' IF i change name in C# dll to SCS3OverwPg, it show error of structure redifinition Pls help me.

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  • Inheritance - initialization problem

    - by dumbquestion
    I have a c++ class derived from a base class in a framework. The derived class doesn't have any data members because I need it to be freely convertible into a base class and back - the framework is responsible for loading and saving the objects and I can't change it. My derived class just has functions for accessing the data. But there are a couple of places where I need to store some temporary local variables to speed up access to data in the base class. mydata* MyClass::getData() { if ( !m_mydata ) { // set to NULL in the constructor m_mydata = some_long_and complex_operation_to_get_the_data_in_the_base() } return m_mydata; } The problem is if I just access the object by casting the base class pointer returned from the framework to MyClass* the ctor for MyClass is never called and m_mydata is junk. Is there a way of only initializing the m_mydata pointer once?

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  • How to call a bool function...

    - by Gerri
    Hello, I did not see anything that address my particular code problem. I have a bool function in a class; the bool function is named: bool Triplet::operator ==(const Triplet& operand)const And I am trying to call it in Main but having problems just getting the call right. Apparently if I leave out any thing in the wording it gives an error that I have too few aruguments and if I try to use the entire wording of the function, I get the error that I need a semi-colon, but I already have a semi-colon at the end of the call, so I know that something else is wrong and I simply cannot figure out what is wrong! Any help would be appreciated! Thanks in advance.

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  • Error message in XSLT with C# extension function

    - by iHeartGreek
    Hi! I am received the following error while trying to implement a C# extension function in XSLT. Extension function parameters or return values which have CLR type 'Char[]' are not supported.** code: <xsl:variable name="stringList"> <xsl:value-of select="extension:GetList('AAA BBB CCC', ' ')"/> </xsl:variable> <msxsl:script language="C#" implements-prefix="extension"> <![CDATA[ public string[] GetList(string str, char[] delimiter) { ... ... return str.Split(delimiter, StringSplitOptions.None); } ]]> </msxsl:script> Can someone explain this error message and how to get past it? Thanks!

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  • Accessing "Mapi32.dll" with C#. [not solved]

    - by Code Smack
    Hello, I am using VS 2008 C# Windows Application. I have this DLL Import I am trying to use. [DllImport("Mapi32.dll", PreserveSig = true)] private static extern void WrapCompressedRTFStream( [MarshalAs(UnmanagedType.Interface)] UCOMIStream lpCompressedRTFStream, uint ulflags, [MarshalAs(UnmanagedType.Interface)] out UCOMIStream lpUncompressedRTFStream ); public const uint MAPI_MODIFY = 0x00000001; public const uint STORE_UNCOMPRESSED_RTF = 0x00008000; I have a compressed string that is in CompressedRFTFormat. How do I pass the string into the WrapCompressedRTFStream? I do not understand what the method is expecting. I am trying to use it on a button. RichText1.text = WrapCompressedRTFStream(_CompressedRichText.ToString(),something,somethingelse); The first error I get is "cannot convert from 'string' to 'System.Runtime.InteropServices.UCOMIStream" I hope someone who understands this posts an answer that helps!

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