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  • Sha256 is giving junk output

    - by user1746617
    hey can u be more specific on how to convert to bin to hex. bool HashStatus::calculate_digest_value(char * path,unsigned char * output) { FILE* file = fopen(path, "rb"); if(!file) { g_message("SignatureValidator::VerifyReferences,file not opened"); return -1; } unsigned char hash[SHA256_DIGEST_LENGTH]; SHA256_CTX sha256; SHA256_Init(&sha256); const int bufSize = 32768; unsigned char* buffer = malloc(bufSize); int bytesRead = 0; if(!buffer) return NULL; while((bytesRead = fread(buffer, 1, bufSize, file))) { g_message("calculate digest value,verify.cpp::%s",buffer); SHA256_Update(&sha256, buffer, bytesRead); } SHA256_Final(hash, &sha256); g_message("verify.cpp,after final"); sha256_hash_string(hash, output); g_message("verify.cpp,after sha256_hash_string %s",hash); fclose(file); free(buffer); return true; } this is my code to convert file data into hash using sha256 openssl function o/p is :1d54e12333988471354907a760b9cde861423615bb5255ee837e3b27b32366 but actual o/p is:HVThAjM5iEcTVJB6dgC5zehhQjYVu1JV7oN+OyezI2Y= can you guys please help me with whatz wrong with this code,ASAP and i'm new to this please guide me step by step and in detail..

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  • c++ code cons/pros

    - by VirusEcks
    below i have a code that runs in most of my simple programs .. . i want to know if it's good/bad ... and cons/pros . . win32 header file: win32.h #include <windows.h> #include <process.h> #include <stdarg.h> main header file: inc.h #include "win32.h" #ifndef INCS #define INCS #define DD #else #define DD extern #endif #ifndef VARS #define titlen L"my program" #endif DD wchar_t gtitle[512]; DD wchar_t gclass[512]; DD wchar_t gdir[32767]; #include "resources.h" #include "commonfunctions.h" then all files have something like this commonfunctions.h DD inline bool icmp( const char *String1, const char *String2 ) { if ( _stricmp( String1, String2 ) == 0 ) { return true; } return false; } DD inline bool scmp( const char *String1, const char *String2 ) { if ( strcmp( String1, String2 ) == 0 ) { return true; } return false; } all global variables have DD infront of them and all functions have DD too . is there a bad side of this ? . i came up with this idea and it wasn't problematic at all in small programs . but before i apply it in a large project will it be problematic ?. thanks in advance.

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  • C++ reference variables

    - by avd
    I have these two functions (with Point2D & LineVector (has 2 Point2D member variables) classes and SQUARE macro predefined) inline float distance(const Point2D &p1,const Point2D &p2) { return sqrt(SQUARE(p2.getX()-p1.getX())+SQUARE(p2.getY()-p1.getY())); } inline float maxDistance(const LineVector &lv1,const LineVector &lv2) { return max(distance(lv1.p1,lv2.p2),distance(lv1.p2,lv2.p1)); } but it gives compilation error in maxDistance() function (line 238) saying: /usr/lib/gcc/i686-pc-cygwin/3.4.4/include/c++/bits/stl_iterator_base_types.h: In instantiation of `std::iterator_traits<Point2D>': quadrilateral.cpp:238: instantiated from here /usr/lib/gcc/i686-pc-cygwin/3.4.4/include/c++/bits/stl_iterator_base_types.h:129: error: no type named `iterator_category' in `class Point2D' /usr/lib/gcc/i686-pc-cygwin/3.4.4/include/c++/bits/stl_iterator_base_types.h:130: error: no type named `value_type' in `class Point2D ' /usr/lib/gcc/i686-pc-cygwin/3.4.4/include/c++/bits/stl_iterator_base_types.h:131: error: no type named `difference_type' in `class Point2D' /usr/lib/gcc/i686-pc-cygwin/3.4.4/include/c++/bits/stl_iterator_base_types.h:132: error: no type named `pointer' in `class Point2D' /usr/lib/gcc/i686-pc-cygwin/3.4.4/include/c++/bits/stl_iterator_base_types.h:133: error: no type named `reference' in `class Point2D' Please suggest what is the error?

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  • Instantiating a class within a class

    - by Ink-Jet
    Hello. I'm trying to instantiate a class within a class, so that the outer class contains the inner class. This is my code: #include <iostream> #include <string> class Inner { private: std::string message; public: Inner(std::string m); void print() const; }; Inner::Inner(std::string m) { message = m; } void Inner::print() const { std::cout << message << std::endl; std::cout << message << std::endl; } class Outer { private: std::string message; Inner in; public: Outer(std::string m); void print() const; }; Outer::Outer(std::string m) { message = m; } void Outer::print() const { std::cout << message << std::endl; } int main() { Outer out("Hello world."); out.print(); return 0; } "Inner in", is my attempt at containing the inner within the outer, however, when I compile, i get an error that there is no matching function for call to Inner::Inner(). What have I done wrong? Thanks.

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  • printing out dictionnaires

    - by kyril
    I have a rather specific question: I want to print out characters at a specific place using the \033[ syntax. This is what the code below should do: (the dict cells has the same keys as coords but with either '*' or '-' as value.) coords = {'x'+str(x)+'y'+str(y) : (x,y) for x,y, in itertools.product(range(60), range(20))} for key, value in coords.items(): char = cells[key] x,y = value HORIZ=str(x) VERT=str(y) char = str(char) print('\033['+VERT+';'+HORIZ+'f'+char) However, I noticed that if I put this into a infinite while loop, it does not always prints the same characters at the same position. There are only slight changes, but it deletes some and puts them back in after some loops. I already tried it with lists, and there it seems to behave just fine, so I tend to think it has something todo with the dict, but I can not figure out what it could be. You can see the Problem in a console here: SharedConsole.I am happy for every tip on this matter. On a related topic: After the printing, some changes should be made at the values of the cells dict, but for reason unknown to me, the only the first two rules are executed and the rest is ignored. The rules should test how many neighbours (which is in population) are around the cell and apply the according rule. In my implemention of this I have some kind of weird tumor growth (which should not happen, as if there more than three around they should the cell should die) (see FreakingTumor): if cells_copy [coord] == '-': if population == 3: cells [coord] = '*' if cells_copy [coord] == '*': if population > 3: cells [coord] = '-' elif population <= 1: cells [coord] = '-' elif population == 2 or 3: cells [coord] = '*' I checked the population variable several times, so I am quite sure that is not the matter. I am sorry for the slow consoles. Thanks in advance! Kyril

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  • OpenCV compare two images and get different pixels

    - by Richard Knop
    For some reason the code bellow is not working. I have two 640*480 images which are very similar but not the same (at least few hundred/thousand pixels should be different). This is how I am comparing them and counting different pixels: unsigned char* row; unsigned char* row2; int count = 0; // this happens in a loop // fIplImageHeader is current image // lastFIplImageHeader is image from previous iteration if ( NULL != lastFIplImageHeader->imageData ) { for( int y = 0; y < fIplImageHeader->height; y++ ) { row = &CV_IMAGE_ELEM( fIplImageHeader, unsigned char, y, 0 ); row2 = &CV_IMAGE_ELEM( lastFIplImageHeader, unsigned char, y, 0 ); for( int x = 0; x < fIplImageHeader->width*fIplImageHeader->nChannels; x += fIplImageHeader->nChannels ) { if (row[x] == row2[x]) // the pixel in the first channel (usually G) { count++; } if (row[x+1] == row2[x+1]) // ... second channel (usually B) { count++; } if (row[x+2] == row2[x+2]) // ... third channel (usually R) { count++; } } } } Now at the end I get number 3626 which would seem alright. But, I tried opening one of the images in MS Paint and drawing thick red lines all over it which should increase the number of different pixels substantially. I got the same number again: 3626. Obviously I am doing something wrong here. I am comparing these images in a loop. This line is before the loop: IplImage* lastFIplImageHeader = cvCreateImageHeader(cvSize(640, 480), 8, 3); Then inside the loop I load images like this: IplImage* fIplImageHeader = cvLoadImage( filePath.c_str() ); // here I compare the pixels (the first code snippet) lastFIplImageHeader->imageData = fIplImageHeader->imageData; So lastFIplImageHeader is storing the image from the previous iteration and fIplImageHeader is storing the current image.

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  • MySQL Datefields: duplicate or calculate?

    - by Konerak
    We are using a table with a structure imposed upon us more than 10 years ago. We are allowed to add columns, but urged not to change existing columns. Certain columns are meant to represent dates, but are put in different format. Amongst others: * CHAR(6): YYMMDD * CHAR(6): DDMMYY * CHAR(8): YYYYMMDD * CHAR(8): DDMMYYYY * DATE * DATETIME Since we now would like to do some more complex queries, using advanced date functions, my manager proposed to d*uplicate those problem columns* to a proper FORMATTED_OLDCOLUMNNAME column using a DATE or DATETIME format. Is this the way to go? Couldn't we just use the STR_TO_DATE function each time we accessed the columns? To avoid every query having to copy-paste the function, I could still work with a view or a stored procedure, but duplicating data to avoid recalculation sounds wrong. Solutions I see (I guess I prefer 2.2.1) 1. Physically duplicate columns 1.1 In the same table 1.1.1 Added by each script that does a modification (INSERT/UPDATE/REPLACE/...) 1.1.2 Maintained by a trigger on each modification 1.2 In a separate table 1.2.1 Added by each script that does a modification (INSERT/UPDATE/REPLACE/...) 1.2.2 Maintained by a trigger on each modification 2. On-demand transformation 2.1 Each query has to perform the transformation 2.1.1 Using copy-paste in the source code 2.1.2 Using a library 2.1.3 Using a STORED PROCEDURE 2.2 A view performs the transformation 2.2.1 A separate table replacing the entire table 2.2.2 A separate table just adding the date-fields for the primary keys Am I right to say it's better to recalculate than to store? And would a view be a good solution?

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  • Qtimer not timing out QT, C++

    - by realz
    Hi, I am learning C++ and using QT. I have a small program in which I am trying to update the text of the PushButton every second. The label being current time. I have a timer that should time out every second, but seems like it never does. here's the code. Header File #ifndef _HELLOFORM_H #define _HELLOFORM_H #include "ui_HelloForm.h" class HelloForm : public QDialog { public: HelloForm(); virtual ~HelloForm(); public slots: void textChanged(const QString& text); void updateCaption(); private: Ui::HelloForm widget; }; #endif /* _HELLOFORM_H */ CPP file #include "HelloForm.h" #include <QTimer> #include <QtGui/QPushButton> #include <QTime> HelloForm::HelloForm(){ widget.setupUi(this); widget.pushButton->setText(QTime::currentTime().toString()); widget.pushButton->setFont(QFont( "Times", 9, QFont::Bold ) ); QTimer *timer = new QTimer(this); connect(timer, SIGNAL(timeout()), SLOT(updateCaption())); timer->start(1000); connect(widget.pushButton, SIGNAL(clicked()), qApp, SLOT(quit()) ); connect(widget.nameEdit, SIGNAL(textChanged(const QString&)), this, SLOT(textChanged(const QString&))); } HelloForm::~HelloForm() { } void HelloForm::textChanged(const QString& text) { if (0 < text.trimmed().length()) { widget.helloEdit->setText("Hello " + text.trimmed() + "!"); } else { widget.helloEdit->clear(); } } void HelloForm::updateCaption() { QString myVar; myVar = QTime::currentTime().toString(); widget.pushButton->setText(myVar); } Any help will be greatly appreciated... The PushButton's text never changes...

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  • Ways to make (relatively) safe assumptions about the type of concrete subclasses?

    - by Kylotan
    I have an interface (defined as a abstract base class) that looks like this: class AbstractInterface { public: bool IsRelatedTo(const AbstractInterface& other) const = 0; } And I have an implementation of this (constructors etc omitted): class ConcreteThing { public: bool IsRelatedTo(const AbstractInterface& other) const { return m_ImplObject.has_relationship_to(other.m_ImplObject); } private: ImplementationObject m_ImplObject; } The AbstractInterface forms an interface in Project A, and the ConcreteThing lives in Project B as an implementation of that interface. This is so that code in Project A can access data from Project B without having a direct dependency on it - Project B just has to implement the correct interface. Obviously the line in the body of the IsRelatedTo function cannot compile - that instance of ConcreteThing has an m_ImplObject member, but it can't assume that all AbstractInterfaces do, including the other argument. In my system, I can actually assume that all implementations of AbstractInterface are instances of ConcreteThing (or subclasses thereof), but I'd prefer not to be casting the object to the concrete type in order to get at the private member, or encoding that assumption in a way that will crash without a diagnostic later if this assumption ceases to hold true. I cannot modify ImplementationObject, but I can modify AbstractInterface and ConcreteThing. I also cannot use the standard RTTI mechanism for checking a type prior to casting, or use dynamic_cast for a similar purpose. I have a feeling that I might be able to overload IsRelatedTo with a ConcreteThing argument, but I'm not sure how to call it via the base IsRelatedTo(AbstractInterface) method. It wouldn't get called automatically as it's not a strict reimplementation of that method. Is there a pattern for doing what I want here, allowing me to implement the IsRelatedTo function via ImplementationObject::has_relationship_to(ImplementationObject), without risky casts? (Also, I couldn't think of a good question title - please change it if you have a better one.)

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  • What are the linkage of the following functions?

    - by Derui Si
    When I was reading the c++ 03 standard (7.1.1 Storage class specifiers [dcl.stc]), there are some examples as below, I'm not able to tell how the linkage of each successive declarations is determined? Could anyone help here? Thanks in advance! static char* f(); // f() has internal linkage char* f() { /* ... */ } // f() still has internal linkage char* g(); // g() has external linkage static char* g() { /* ... */ } // error: inconsistent linkage void h(); inline void h(); // external linkage inline void l(); void l(); // external linkage inline void m(); extern void m(); // external linkage static void n(); inline void n(); // internal linkage static int a; // a has internal linkage int a; // error: two definitions static int b; // b has internal linkage extern int b; // b still has internal linkage int c; // c has external linkage static int c; // error: inconsistent linkage extern int d; // d has external linkage static int d; // error: inconsistent linkage UPD: Additionally, how can I understand the statement in the standard, " The linkages implied by successive declarations for a given entity shall agree. That is, within a given scope, each declaration declaring the same object name or the same overloading of a function name shall imply the same linkage. Each function in a given set of overloaded functions can have a different linkage, however."

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  • Operator+ for a subtype of a template classe.

    - by baol
    I have a template class that defines a subtype. I'm trying to define the binary operator+ as a template function, but the compiler cannot resolve the template version of the operator+. #include <iostream> template<typename other_type> struct c { c(other_type v) : cs(v) {} struct subtype { subtype(other_type v) : val(v) {} other_type val; } cs; }; template<typename other_type> typename c<other_type>::subtype operator+(const typename c<other_type>::subtype& left, const typename c<other_type>::subtype& right) { return typename c<other_type>::subtype(left.val + right.val); } // This one works // c<a>::subtype operator+(const c<a>::subtype& left, // const c<a>::subtype& right) // { return c<a>::subtype(left.val + right.val); } int main() { c<int> c1 = 1; c<int> c2 = 2; c<int>::subtype cs3 = c1.cs + c2.cs; std::cerr << cs3.val << std::endl; } I think the reason is because the compiler (g++4.3) cannot guess the template type so it's searching for operator+<int> instead of operator+. What's the reason for that? What elegant solution can you suggest?

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  • Imbricated C++ template

    - by gregseth
    I have the following pattern: template <int a, int b> class MyClass { template <int c> MyClass<a, c> &operator*(MyClass<c, b> const &other) const; }; // ../.. template <int a, int b> template <int c> MyClass<a, c> &MyClass<a, b>::operator*(MyClass<c, b> const &other) const { MyClass<a, c> result; // ..do stuff.. return result; } It doesn't compile, the error message is Error C2975. invalid template argument 'number', constant expression expected. If I replace template <int c> by template <int c, int d> and use it accordignly, it works fine. But I want d to be the same value as b. My questions: Why the example doesn't work? How can I enforce d to be the same than b? Thanks.

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  • Java: over-typed structures? To have many types in Object[]?

    - by HH
    Term over-type structure = a data structure that accepts different types, can be primitive or user-defined. I think ruby supports many types in structures such as tables. I tried a table with types 'String', 'char' and 'File' in Java but errs. How can I have over-typed structure in Java? How to show types in declaration? What about in initilization? Suppose a structure: INDEX VAR FILETYPE //0 -> file FILE //1 -> lineMap SizeSequence //2 -> type char //3 -> binary boolean //4 -> name String //5 -> path String Code import java.io.*; import java.util.*; public class Object { public static void print(char a) { System.out.println(a); } public static void print(String s) { System.out.println(s); } public static void main(String[] args) { Object[] d = new Object[6]; d[0] = new File("."); d[2] = 'T'; d[4] = "."; print(d[2]); print(d[4]); } } Errors Object.java:18: incompatible types found : java.io.File required: Object d[0] = new File("."); ^ Object.java:19: incompatible types found : char required: Object d[2] = 'T'; ^

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  • How to know the type of an object in a list?

    - by nacho4d
    Hi, I want to know the type of object (or type) I have in my list so I wrote this: void **list; //list of references list = new void * [2]; Foo foo = Foo(); const char *not_table [] = {"tf", "ft", 0 }; list[0] = &foo; list[1] = not_table; if (dynamic_cast<LogicProcessor*>(list[0])) { //ERROR here ;( printf("Foo was found\n"); } if (dynamic_cast<char*> (list[0])) { //ERROR here ;( printf("char was found\n"); } but I get : error: cannot dynamic_cast '* list' (of type 'void*') to type 'class Foo*' (source is not a pointer to class) error: cannot dynamic_cast '* list' (of type 'void*') to type 'char*' (target is not pointer or reference to class) Why is this? what I am doing wrong here? Is dynamic_cast what I should use here? Thanks in advance EDIT: I know above code is much like plain C and surely sucks from the C++ point of view but is just I have the following situation and I was trying something before really implementing it: I have two arrays of length n but both arrays will never have an object at the same index. Hence, or I have array1[i]!=NULL or array2[i]!=NULL. This is obviously a waste of memory so I thought everything would be solved if I could have both kind of objects in a single array of length n. I am looking something like Cocoa's (Objective-C) NSArray where you don't care about the type of the object to be put in. Not knowing the type of the object is not a problem since you can use other method to get the class of a certain later. Is there something like it in c++ (preferably not third party C++ libraries) ? Thanks in advance ;)

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  • What are the C# equivalent of these C++ structs

    - by Otake
    typedef union _Value { signed char c; unsigned char b; signed short s; unsigned short w; signed long l; unsigned long u; float f; double *d; char *p; } Value; typedef struct _Field { WORD nFieldId; BYTE bValueType; Value Value; } Field; typedef struct _Packet { WORD nMessageType; WORD nSecurityType; BYTE bExchangeId; BYTE bMarketCenter; int iFieldCount; char cSymbol[20]; Field FieldArr[1]; } Packet; What are the C# equivalent of these C++ structs? I am migrating some code from C++ to C# and having problems to migrate these structures. I had tried a few things but I always ended up having marshalling problems.

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  • Problem in data binding in NSString?

    - by Rajendra Bhole
    Hi, I selecting the row of the table. The text of the row i stored in the application delegate object as a NSString. That NSString i want to retrieving or binding in SELECT statement of SQLite query, For that i written code in the TableView Class (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath { selectedText = [appDelegate.categoryArray objectAtIndex:indexPath.row]; appDelegate.selectedTextOfRow = selectedText; ListOfPrayersViewController *listVC = [[ListOfPrayersViewController alloc] init]; [self.navigationController pushViewController:listVC animated:YES]; [listVC release]; } and database class class code is. + (void) getDuas:(NSString *)dbPath{ if(sqlite3_open([dbPath UTF8String], &database) == SQLITE_OK){ SalahAppDelegate *appDelegate = (SalahAppDelegate *)[[UIApplication sharedApplication] delegate]; NSString *categoryTextForQuery =[NSString stringWithFormat:@"SELECT Category FROM Prayer WHERE Category ='%s'", appDelegate.selectedTextOfRow ]; NSLog(@"The Text %@", categoryTextForQuery); //const char *sqlQuery1 = (char *)categoryTextForQuery; //const char *sqlQuery = "SELECT Category FROM Prayer WHERE Category = 'Invocations for the beginning of the prayer'"; sqlite3_stmt *selectstmt; if(sqlite3_prepare_v2(database, [categoryTextForQuery UTF8String], -1, &selectstmt, NULL) == SQLITE_OK){ appDelegate.duasArray =[[NSMutableArray alloc] init]; while(sqlite3_step(selectstmt) == SQLITE_ROW){ NSString *dua = [[NSString alloc] initWithCString:(char *)sqlite3_column_text(selectstmt,0) encoding:NSASCIIStringEncoding]; Prayer *prayerObj = [[Prayer alloc] initwithDuas:dua]; prayerObj.DuaName = dua; [appDelegate.duasArray addObject:prayerObj]; } } } } The code is comes out of loop on the statement or starting the loop of the while(sqlite3_step(selectstmt) == SQLITE_ROW) Why? How i bind the table selected text in SELECT statement of sqlite?

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  • Efficiently get the size of a parameter pack up to a certain index

    - by NmdMystery
    I want to be able to determine the number of bytes that are in a subset of a parameter pack from 0 to a given index. Right now I'm using a non-constexpr way of doing this. Below is my code: template <size_t index, typename... args> struct pack_size_index; template <size_t index, typename type_t, typename... args> struct pack_size_index <index, type_t, args...> { static const size_t index_v = index; static const size_t value(void) { if (index_v > 0) { return sizeof(type_t) + pack_size_index<index - 1, args...>::value(); } return 0; } }; template <size_t index> struct pack_size_index <index> { static const size_t index_v = index; static const size_t value(void) { return 0; } }; Usage: //output: 5 (equal to 1 + 4) std::cout << pack_size_index<2, bool, float, int, double>::value() << std::endl; //output: 20 (equal to 8 + 8 + 4) std::cout << pack_size_index<3, double, double, float, int>::value() << std::endl; This gets the job done, but this uses runtime comparison and the resulting executable increases in size rapidly whenever this is used. What's a less expensive way of doing this?

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  • How can I speed-up this loop (in C)?

    - by splicer
    Hi! I'm trying to parallelize a convolution function in C. Here's the original function which convolves two arrays of 64-bit floats: void convolve(const Float64 *in1, UInt32 in1Len, const Float64 *in2, UInt32 in2Len, Float64 *results) { UInt32 i, j; for (i = 0; i < in1Len; i++) { for (j = 0; j < in2Len; j++) { results[i+j] += in1[i] * in2[j]; } } } In order to allow for concurrency (without semaphores), I created a function that computes the result for a particular position in the results array: void convolveHelper(const Float64 *in1, UInt32 in1Len, const Float64 *in2, UInt32 in2Len, Float64 *result, UInt32 outPosition) { UInt32 i, j; for (i = 0; i < in1Len; i++) { if (i > outPosition) break; j = outPosition - i; if (j >= in2Len) continue; *result += in1[i] * in2[j]; } } The problem is, using convolveHelper slows down the code about 3.5 times (when running on a single thread). Any ideas on how I can speed-up convolveHelper, while maintaining thread safety?

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  • Operator Overloading << in c++

    - by thlgood
    I'm a fresh man in C++. I write this simple program to practice Overlaoding. This is my code: #include <iostream> #include <string> using namespace std; class sex_t { private: char __sex__; public: sex_t(char sex_v = 'M'):__sex__(sex_v) { if (sex_v != 'M' && sex_v != 'F') { cerr << "Sex type error!" << sex_v << endl; __sex__ = 'M'; } } const ostream& operator << (const ostream& stream) { if (__sex__ == 'M') cout << "Male"; else cout << "Female"; return stream; } }; int main(int argc, char *argv[]) { sex_t me('M'); cout << me << endl; return 0; } When I compiler it, It print a lots of error message: The error message was in a mess. It's too hard for me to found useful message sex.cpp: ???‘int main(int, char**)’?: sex.cpp:32:10: ??: ‘operator<<’?‘std::cout << me’????? sex.cpp:32:10: ??: ???: /usr/include/c++/4.6/ostream:110:7: ??: std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(std::basic_ostre

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  • insertvalue function in stack class is not calling when pointing by smartpointer class? please expai

    - by user323422
    template< class Type > class cStack { Type *m_array; int m_Top; int m_Size; public:cStack(); cStack(const Type&); cStack(const cStack<Type> &); bool Is_Full(); bool Is_Empty(); void InsertValue(const Type&); void RemeoveValue(); ~cStack(); }; template< class Type > class Smartpointer { cStack<Type> *sPtr; public: Smartpointer(); Smartpointer(const Type&); Type* operator->(); Type& operator*(); }; int main() { Smartpointer<int> sptr(1); sptr->InsertValue(2);//its not calling insertvalue } }

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  • Problem Initializing an Array Of Structs

    - by FallSe7en
    I am trying to initialize the following array of the following struct, but my code isn't compiling. Can anybody help me out? The struct/array: struct DiningCarSeat { int status; int order; int waiterNum; Lock customerLock; Condition customer; DiningCarSeat(seatNum) { char* tempLockName; sprintf(tempLockName, "diningCarSeatLock%d", seatNum); char* tempConditionName; sprintf(tempConditionName, "diningCarSeatCondition%d", seatNum); status = 0; order = 0; waiterNum = -1; customerLock = new Lock(tempLockName); customer = new Condition(tempConditionName); } } diningCarSeat[DINING_CAR_CAPACITY]; The relevant errors: ../threads/threadtest.cc: In constructor `DiningCarSeat::DiningCarSeat(int)': ../threads/threadtest.cc:58: error: no matching function for call to `Lock::Lock()' ../threads/synch.h:66: note: candidates are: Lock::Lock(const Lock&) ../threads/synch.h:68: note: Lock::Lock(char*) ../threads/threadtest.cc:58: error: no matching function for call to `Condition::Condition()' ../threads/synch.h:119: note: candidates are: Condition::Condition(const Condition&) ../threads/synch.h:121: note: Condition::Condition(char*) ../threads/threadtest.cc:63: error: expected primary-expression before '.' token ../threads/threadtest.cc:64: error: expected primary-expression before '.' token ../threads/threadtest.cc: At global scope: ../threads/threadtest.cc:69: error: no matching function for call to `DiningCarSeat::DiningCarSeat()' ../threads/threadtest.cc:51: note: candidates are: DiningCarSeat::DiningCarSeat(const DiningCarSeat&) ../threads/threadtest.cc:58: note: DiningCarSeat::DiningCarSeat(int) Thanks in advance!

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  • C++0x Smart Pointer Comparisons: Inconsistent, what's the rationale?

    - by GManNickG
    In C++0x (n3126), smart pointers can be compared, both relationally and for equality. However, the way this is done seems inconsistent to me. For example, shared_ptr defines operator< be equivalent to: template <typename T, typename U> bool operator<(const shared_ptr<T>& a, const shared_ptr<T>& b) { return std::less<void*>()(a.get(), b.get()); } Using std::less provides total ordering with respect to pointer values, unlike a vanilla relational pointer comparison, which is unspecified. However, unique_ptr defines the same operator as: template <typename T1, typename D1, typename T2, typename D2> bool operator<(const unique_ptr<T1, D1>& a, const unique_ptr<T2, D2>& b) { return a.get() < b.get(); } It also defined the other relational operators in similar fashion. Why the change in method and "completeness"? That is, why does shared_ptr use std::less while unique_ptr uses the built-in operator<? And why doesn't shared_ptr also provide the other relational operators, like unique_ptr? I can understand the rationale behind either choice: with respect to method: it represents a pointer so just use the built-in pointer operators, versus it needs to be usable within an associative container so provide total ordering (like a vanilla pointer would get with the default std::less predicate template argument) with respect to completeness: it represents a pointer so provide all the same comparisons as a pointer, versus it is a class type and only needs to be less-than comparable to be used in an associative container, so only provide that requirement But I don't see why the choice changes depending on the smart pointer type. What am I missing? Bonus/related: std::shared_ptr seems to have followed from boost::shared_ptr, and the latter omits the other relational operators "by design" (and so std::shared_ptr does too). Why is this?

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  • c# logic to get the first non-repeating(distinct) character from the string

    - by NoviceToDotNet
    In c# i want to create logic that if i a string like abcabda is passed to a method then it should return first non repeative character from string like in above it should return c. i am unable to convert a string to array of character then how to make comparison of each array character to the string and return the first non repeative character. CanI make it like this? class A { static void main() { A a=new A(); char ch=a.m1(abcabd); } } class B { char m1(string s) { string s1=s; char[] ch1=new char[s.length]; for(int x=0; x<s.length;x++) { ch1[x]=s[x]; } for(int x=0; x<s.length; x++) { for(int y=0; y<s.lenth; y++) { if(s[x]=ch1[y]) { /// here i am confused how to create logic for comparison please let me know // and how to return the character } } } } }

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  • I am trying to access the individual bytes in a floating point number and I am getting unexpected results

    - by oweinh
    So I have this so far: #include <iostream> #include <string> #include <typeinfo> using namespace std; int main () { float f = 3.45; // just an example fp# char* ptr = (char*)&f; // a character pointer to the first byte of the fp#? cout << int(ptr[0]) << endl; // these lines are just to see if I get what I cout << int(ptr[1]) << endl; // am looking for... I want ints that I can cout << int(ptr[2]) << endl; // otherwise manipulate. cout << int(ptr[3]) << endl; } the result is: -51 -52 92 64 so obviously -51 and -52 are not in the byte range that I would expect for a char... I have taken information from similar questions to arrive at this code and from all discussions, a conversion from char to int is straightforward. So why negative values? I am trying to look at a four-byte number, therefore I would expect 4 integers, each in the range 0-255. I am using Codeblocks 13.12 with gcc 4.8.1 with option -std=C++11 on a Windows 8.1 device.

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  • Reading/Writing/Modifying a struct in C

    - by user1016401
    I am taking some information from a user (name, address, contact number) and store it in a struct. I then store this in a file which is opened in "r+" mode. I try reading it line by line and see if the entry I am trying to enter already exists, in which case I exit. Otherwise I append this entry at the end of the file. The problem is that when I open the file in "r+" mode, it gives me Segmentation fault! Here is the code: struct cust{ char *frstnam; char *lastnam; char *cntact; char *add; }; Now consider this function. I am passing a struct of information in this function. Its job is to check if this struct already exists else append it to end of file. void check(struct cust c) { struct cust cpy; FILE *f; f=fopen("Customer.txt","r+"); int num=0; if (f!= NULL){ while (!feof(f)) { num++; fread(&cpy,sizeof(struct cust),1,f); if ((cpy.frstnam==c.frstnam)&(cpy.lastnam==c.lastnam)&(cpy.cntact==c.cntact)&(cpy.add==c.add)) { printf("Hi %s %s. Nice to meet you again. You live at %s and your contact number is %s\n", cpy.frstnam,cpy.lastnam,cpy.add,cpy.cntact); return; } } fwrite(&c,sizeof(struct cust),1,f); fclose (f); } printf("number of lines read is %d\n",num); }

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