Search Results

Search found 2727 results on 110 pages for 'operator overloading'.

facebook twitter digg google delicious technorati stumbleupon myspace wordpress linkedin gmail igoogle windows live tumblr viadeo yahoo buzz yahoo mail yahoo bookmarks favorites email print

Page 4/110 | < Previous Page | 1 2 3 4 5 6 7 8 9 10 11 12  | Next Page >

  • C++ Operator Ambiguity

    - by Scott
    Forgive me, for I am fairly new to C++, but I am having some trouble regarding operator ambiguity. I think it is compiler-specific, for the code compiled on my desktop. However, it fails to compile on my laptop. I think I know what's going wrong, but I don't see an elegant way around it. Please let me know if I am making an obvious mistake. Anyhow, here's what I'm trying to do: I have made my own vector class called Vector4 which looks something like this: class Vector4 { private: GLfloat vector[4]; ... } Then I have these operators, which are causing the problem: operator GLfloat* () { return vector; } operator const GLfloat* () const { return vector; } GLfloat& operator [] (const size_t i) { return vector[i]; } const GLfloat& operator [] (const size_t i) const { return vector[i]; } I have the conversion operator so that I can pass an instance of my Vector4 class to glVertex3fv, and I have subscripting for obvious reasons. However, calls that involve subscripting the Vector4 become ambiguous to the compiler: enum {x, y, z, w} Vector4 v(1.0, 2.0, 3.0, 4.0); glTranslatef(v[x], v[y], v[z]); Here are the candidates: candidate 1: const GLfloat& Vector4:: operator[](size_t) const candidate 2: operator[](const GLfloat*, int) <built-in> Why would it try to convert my Vector4 to a GLfloat* first when the subscript operator is already defined on Vector4? Is there a simple way around this that doesn't involve typecasting? Am I just making a silly mistake? Thanks for any help in advance.

    Read the article

  • Binary operator overloading on a templated class (C++)

    - by GRB
    Hi all, I was recently trying to gauge my operator overloading/template abilities and as a small test, created the Container class below. While this code compiles fine and works correctly under MSVC 2008 (displays 11), both MinGW/GCC and Comeau choke on the operator+ overload. As I trust them more than MSVC, I'm trying to figure out what I'm doing wrong. Here is the code: #include <iostream> using namespace std; template <typename T> class Container { friend Container<T> operator+ <> (Container<T>& lhs, Container<T>& rhs); public: void setobj(T ob); T getobj(); private: T obj; }; template <typename T> void Container<T>::setobj(T ob) { obj = ob; } template <typename T> T Container<T>::getobj() { return obj; } template <typename T> Container<T> operator+ <> (Container<T>& lhs, Container<T>& rhs) { Container<T> temp; temp.obj = lhs.obj + rhs.obj; return temp; } int main() { Container<int> a, b; a.setobj(5); b.setobj(6); Container<int> c = a + b; cout << c.getobj() << endl; return 0; } This is the error Comeau gives: Comeau C/C++ 4.3.10.1 (Oct 6 2008 11:28:09) for ONLINE_EVALUATION_BETA2 Copyright 1988-2008 Comeau Computing. All rights reserved. MODE:strict errors C++ C++0x_extensions "ComeauTest.c", line 27: error: an explicit template argument list is not allowed on this declaration Container<T> operator+ <> (Container<T>& lhs, Container<T>& rhs) ^ 1 error detected in the compilation of "ComeauTest.c". I'm having a hard time trying to get Comeau/MingGW to play ball, so that's where I turn to you guys. It's been a long time since my brain has melted this much under the weight of C++ syntax, so I feel a little embarrassed ;). Thanks in advance. EDIT: Eliminated an (irrelevant) lvalue error listed in initial Comeau dump.

    Read the article

  • operator<< cannot output std::endl -- Fix?

    - by dehmann
    The following code gives an error when it's supposed to output just std::endl: #include <iostream> #include <sstream> struct MyStream { std::ostream* out_; MyStream(std::ostream* out) : out_(out) {} std::ostream& operator<<(const std::string& s) { (*out_) << s; return *out_; } }; template<class OutputStream> struct Foo { OutputStream* out_; Foo(OutputStream* out) : out_(out) {} void test() { (*out_) << "OK" << std::endl; (*out_) << std::endl; // ERROR } }; int main(int argc, char** argv){ MyStream out(&std::cout); Foo<MyStream> foo(&out); foo.test(); return EXIT_SUCCESS; } The error is: stream1.cpp:19: error: no match for 'operator<<' in '*((Foo<MyStream>*)this)->Foo<MyStream>::out_ << std::endl' stream1.cpp:7: note: candidates are: std::ostream& MyStream::operator<<(const std::string&) So it can output a string (see line above the error), but not just the std::endl, presumably because std::endl is not a string, but the operator<< definition asks for a string. Templating the operator<< didn't help: template<class T> std::ostream& operator<<(const T& s) { ... } How can I make the code work? Thanks!

    Read the article

  • Visual C++ doesn't operator<< overload

    - by PierreBdR
    I have a vector class that I want to be able to input/output from a QTextStream object. The forward declaration of my vector class is: namespace util { template <size_t dim, typename T> class Vector; } I define the operator<< as: namespace util { template <size_t dim, typename T> QTextStream& operator<<(QTextStream& out, const util::Vector<dim,T>& vec) { ... } template <size_t dim, typename T> QTextStream& operator>>(QTextStream& in,util::Vector<dim,T>& vec) { .. } } However, if I ty to use these operators, Visual C++ returns this error: error C2678: binary '<<' : no operator found which takes a left-hand operand of type 'QTextStream' (or there is no acceptable conversion) A few things I tried: Originaly, the methods were defined as friends of the template, and it is working fine this way with g++. The methods have been moved outside the namespace util I changed the definition of the templates to fit what I found on various Visual C++ websites. The original friend declaration is: friend QTextStream& operator>>(QTextStream& ss, Vector& in) { ... } The "Visual C++ adapted" version is: friend QTextStream& operator>> <dim,T>(QTextStream& ss, Vector<dim,T>& in); with the function pre-declared before the class and implemented after. I checked the file is correctly included using: #pragma message ("Including vector header") And everything seems fine. Doesn anyone has any idea what might be wrong?

    Read the article

  • What are the default return values for operator< and operator[] in C++ (Visual Studio 6)?

    - by DustOff
    I've inherited a large Visual Studio 6 C++ project that needs to be translated for VS2005. Some of the classes defined operator< and operator[], but don't specify return types in the declarations. VS6 allows this, but not VS2005. I am aware that the C standard specifies that the default return type for normal functions is int, and I assumed VS6 might have been following that, but would this apply to C++ operators as well? Or could VS6 figure out the return type on its own? For example, the code defines a custom string class like this: class String { char arr[16]; public: operator<(const String& other) { return something1 < something2; } operator[](int index) { return arr[index]; } }; Would VS6 have simply put the return types for both as int, or would it have been smart enough to figure out that operator[] should return a char and operator< should return a bool (and not convert both results to int all the time)? Of course I have to add return types to make this code VS2005 C++ compliant, but I want to make sure to specify the same type as before, as to not immediately change program behavior (we're going for compatibility at the moment; we'll standardize things later).

    Read the article

  • Default values on arguments in C functions and function overloading in C

    - by inquam
    Converting a C++ lib to ANSI C and it seems like though ANSI C doesn't support default values for function variables or am I mistaken? What I want is something like int funcName(int foo, bar* = NULL); Also, is function overloading possible in ANSI C? Would need const char* foo_property(foo_t* /* this */, int /* property_number*/); const char* foo_property(foo_t* /* this */, const char* /* key */, int /* iter */); Could of course just name them differently but being used to C++ I kinda used to function overloading.

    Read the article

  • Overloading methods that do logically different things, does this break any major principles?

    - by siva.k
    This is something that's been bugging me for a bit now. In some cases you see code that is a series of overloads, but when you look at the actual implementation you realize they do logically different things. However writing them as overloads allows the caller to ignore this and get the same end result. But would it be more sound to name the methods more explicitly then to write them as overloads? public void LoadWords(string filePath) { var lines = File.ReadAllLines(filePath).ToList(); LoadWords(lines); } public void LoadWords(IEnumerable<string> words) { // loads words into a List<string> based on some filters } Would these methods better serve future developers to be named as LoadWordsFromFile() and LoadWordsFromEnumerable()? It seems unnecessary to me, but if that is better what programming principle would apply here? On the flip side it'd make it so you didn't need to read the signatures to see exactly how you can load the words, which as Uncle Bob says would be a double take. But in general is this type of overloading to be avoided then?

    Read the article

  • Custom string class (C++)

    - by Sanctus2099
    Hey guys. I'm trying to write my own C++ String class for educational and need purposes. The first thing is that I don't know that much about operators and that's why I want to learn them. I started writing my class but when I run it it blocks the program but does not do any crash. Take a look at the following code please before reading further: class CString { private: char* cstr; public: CString(); CString(char* str); CString(CString& str); ~CString(); operator char*(); operator const char*(); CString operator+(const CString& q)const; CString operator=(const CString& q); }; First of all I'm not so sure I declared everything right. I tried googleing about it but all the tutorials about overloading explain the basic ideea which is very simple but lack to explain how and when each thing is called. For instance in my = operator the program calls CString(CString& str); but I have no ideea why. I have also attached the cpp file below: CString::CString() { cstr=0; } CString::CString(char *str) { cstr=new char[strlen(str)]; strcpy(cstr,str); } CString::CString(CString& q) { if(this==&q) return; cstr = new char[strlen(q.cstr)+1]; strcpy(cstr,q.cstr); } CString::~CString() { if(cstr) delete[] cstr; } CString::operator char*() { return cstr; } CString::operator const char* () { return cstr; } CString CString::operator +(const CString &q) const { CString s; s.cstr = new char[strlen(cstr)+strlen(q.cstr)+1]; strcpy(s.cstr,cstr); strcat(s.cstr,q.cstr); return s; } CString CString::operator =(const CString &q) { if(this!=&q) { if(cstr) delete[] cstr; cstr = new char[strlen(q.cstr)+1]; strcpy(cstr,q.cstr); } return *this; } For testing I used a code just as simple as this CString a = CString("Hello") + CString(" World"); printf(a); I tried debugging it but at a point I get lost. First it calls the constructor 2 times for "hello" and for " world". Then it get's in the + operator which is fine. Then it calls the constructor for the empty string. After that it get's into "CString(CString& str)" and now I'm lost. Why is this happening? After this I noticed my string containing "Hello World" is in the destructor (a few times in a row). Again I'm very puzzeled. After converting again from char* to Cstring and back and forth it stops. It never get's into the = operator but neither does it go further. printf(a) is never reached. I use VisualStudio 2010 for this but it's basically just standard c++ code and thus I don't think it should make that much of a difference

    Read the article

  • Recursion problem overloading an operator

    - by Tronfi
    I have this: typedef string domanin_name; And then, I try to overload the operator< in this way: bool operator<(const domain_name & left, const domain_name & right){ int pos_label_left = left.find_last_of('.'); int pos_label_right = right.find_last_of('.'); string label_left = left.substr(pos_label_left); string label_right = right.substr(pos_label_right); int last_pos_label_left=0, last_pos_label_right=0; while(pos_label_left!=string::npos && pos_label_right!=string::npos){ if(label_left<label_right) return true; else if(label_left>label_right) return false; else{ last_pos_label_left = pos_label_left; last_pos_label_right = pos_label_right; pos_label_left = left.find_last_of('.', last_pos_label_left); pos_label_right = right.find_last_of('.', last_pos_label_left); label_left = left.substr(pos_label_left, last_pos_label_left); label_right = right.substr(pos_label_right, last_pos_label_right); } } } I know it's a strange way to overload the operator <, but I have to do it this way. It should do what I want. That's not the point. The problem is that it enter in an infinite loop right in this line: if(label_left<label_right) return true; It seems like it's trying to use this overloading function itself to do the comparision, but label_left is a string, not a domain name! Any suggestion?

    Read the article

  • 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

    Read the article

  • C++: Overload != When == Overloaded

    - by Mark W
    Say I have a class where I overloaded the operator == as such: Class A { ... public: bool operator== (const A &rhs) const; ... }; ... bool A::operator== (const A &rhs) const { .. return isEqual; } I already have the operator == return the proper Boolean value. Now I want to extend this to the simple opposite (!=). I would like to call the overloaded == operator and return the opposite, i.e. something of the nature bool A::operator!= (const A &rhs) const { return !( this == A ); } Is this possible? I know this will not work, but it exemplifies what I would like to have. I would like to keep only one parameter for the call: rhs. Any help would be appreciated, because I could not come up with an answer after several search attempts.

    Read the article

  • Operator overloading outside class

    - by bobobobo
    There are two ways to overload operators for a C++ class: Inside class class Vector2 { public: float x, y ; Vector2 operator+( const Vector2 & other ) { Vector2 ans ; ans.x = x + other.x ; ans.y = y + other.y ; return ans ; } } ; Outside class class Vector2 { public: float x, y ; } ; Vector2 operator+( const Vector2& v1, const Vector2& v2 ) { Vector2 ans ; ans.x = v1.x + v2.x ; ans.y = v1.y + v2.y ; return ans ; } (Apparently in C# you can only use the "outside class" method.) In C++, which way is more correct? Which is preferable?

    Read the article

  • Overload assignment operator for assigning sql::ResultSet to struct tm

    - by Luke Mcneice
    Are there exceptions for types which can't have thier assignment operator overloaded? Specifically, I'm wanting to overload the assignment operator of a struct tm (from time.h) so I can assign a sql::ResultSet to it. I already have the conversion logic: sscanf(sqlresult->getString("StoredAt").c_str(), "%d-%d-%d %d:%d:%d", &TempTimeStruct->tm_year, &TempTimeStruct->tm_mon, &TempTimeStruct->tm_mday, &TempTimeStruct->tm_hour, &TempTimeStruct->tm_min, &TempTimeStruct->tm_sec); I tried the overload with this: tm& tm::operator=(sql::ResultSet & results) { /*CODE*/ return *this; } However VS08 reports: error C2511: 'tm &tm::operator =(sql::ResultSet &)' : overloaded member function not found in 'tm'

    Read the article

  • Operator overloading C++ outside class

    - by bobobobo
    Well, so there are 2 ways to overload operators for a C++ class INSIDE CLASS class Vector2 { public: float x, y ; Vector2 operator+( const Vector2 & other ) { Vector2 ans ; ans.x = x + other.x ; ans.y = y + other.y ; return ans ; } } ; OUTSIDE CLASS class Vector2 { public: float x, y ; } ; Vector2 operator+( const Vector2& v1, const Vector2& v2 ) { Vector2 ans ; ans.x = v1.x + v2.x ; ans.y = v1.y + v2.y ; return ans ; } In C# apparently you can only use the OUTSIDE class method The question is, in C++, which is "morer-correcter?" Which is preferable? When is one way better than another?

    Read the article

  • Overload operator in F#

    - by forki23
    Hi, I would like to overload the (/) operator in F# for strings and preserve the meaning for numbers. /// Combines to path strings let (/) path1 path2 = Path.Combine(path1,path2) let x = 3 / 4 // doesn't compile If I try the following I get "Warning 29 Extension members cannot provide operator overloads. Consider defining the operator as part of the type definition instead." /// Combines to path strings type System.String with static member (/) (path1,path2) = Path.Combine(path1,path2) Any ideas? Regards, forki

    Read the article

  • C# String Operator Overloading

    - by ScottSEA
    G'Day Mates - What is the right way (excluding the argument of whether it is advisable) to overload the string operators <, , <= and = ? I've tried it five ways to Sunday and I get various errors - my best shot was declaring a partial class and overloading from there, but it won't work for some reason. namespace System { public partial class String { public static Boolean operator <(String a, String b) { return a.CompareTo(b) < 0; } public static Boolean operator >(String a, String b) { return a.CompareTo(b) > 0; } } }

    Read the article

  • Dynamic Operator Overloading on dict classes in Python

    - by Ishpeck
    I have a class that dynamically overloads basic arithmetic operators like so... import operator class IshyNum: def __init__(self, n): self.num=n self.buildArith() def arithmetic(self, other, o): return o(self.num, other) def buildArith(self): map(lambda o: setattr(self, "__%s__"%o,lambda f: self.arithmetic(f, getattr(operator, o))), ["add", "sub", "mul", "div"]) if __name__=="__main__": number=IshyNum(5) print number+5 print number/2 print number*3 print number-3 But if I change the class to inherit from the dictionary (class IshyNum(dict):) it doesn't work. I need to explicitly def __add__(self, other) or whatever in order for this to work. Why?

    Read the article

  • What is an overloaded operator in c++?

    - by Jeff
    I realize this is a basic question but I have searched online, been to cplusplus.com, read through my book, and I can't seem to grasp the concept of overloaded operators. A specific example from cplusplus.com is: // vectors: overloading operators example #include <iostream> using namespace std; class CVector { public: int x,y; CVector () {}; CVector (int,int); CVector operator + (CVector); }; CVector::CVector (int a, int b) { x = a; y = b; } CVector CVector::operator+ (CVector param) { CVector temp; temp.x = x + param.x; temp.y = y + param.y; return (temp); } int main () { CVector a (3,1); CVector b (1,2); CVector c; c = a + b; cout << c.x << "," << c.y; return 0; } from http://www.cplusplus.com/doc/tutorial/classes2/ but reading through it I'm still not understanding them at all. I just need a basic example of the point of the overloaded operator (which I assume is the "CVector CVector::operator+ (CVector param)"). There's also this example from wikipedia: Time operator+(const Time& lhs, const Time& rhs) { Time temp = lhs; temp.seconds += rhs.seconds; if (temp.seconds >= 60) { temp.seconds -= 60; temp.minutes++; } temp.minutes += rhs.minutes; if (temp.minutes >= 60) { temp.minutes -= 60; temp.hours++; } temp.hours += rhs.hours; return temp; } from "http://en.wikipedia.org/wiki/Operator_overloading" The current assignment I'm working on I need to overload a ++ and a -- operator. Thanks in advance for the information and sorry about the somewhat vague question, unfortunately I'm just not sure on it at all.

    Read the article

  • Why friend function is preferred to member function for operator<<

    - by skydoor
    When you are going to print an object, a friend operator<< is used. Can we use member function for operator<< ? class A { public: void operator<<(ostream& i) { i<<"Member function";} friend ostream& operator<<(ostream& i, A& a) { i<<"operator<<"; return i;} }; int main () { A a; A b; A c; cout<<a<<b<<c<<endl; a<<cout; return 0; } One point is that friend function enable us to use it like this cout<<a<<b<<c What other reasons?

    Read the article

  • Quick, Beginner C++ Overloading Question - Getting the compiler to perceive << is defined for a spec

    - by Francisco P.
    Hello everyone. I edited a post of mine so I coul I overloaded << for a class, Score (defined in score.h), in score.cpp. ostream& operator<< (ostream & os, const Score & right) { os << right.getPoints() << " " << right.scoreGetName(); return os; } (getPoints fetches an int attribute, getName a string one) I get this compiling error for a test in main(), contained in main.cpp binary '<<' : no operator found which takes a right-hand operand of type 'Score' (or there is no acceptable conversion) How come the compiler doesn't 'recognize' that overload as valid? (includes are proper) Thanks for your time.

    Read the article

  • Can overloading is possible with two version of function, constant member function and function with

    - by GG
    Hello, I just came across various overloading methods like type of parameter passed, varying number of parameters, return type etc. I just want to know that can I overload a function with following two version //function which can modify member String& MyClass::doSomething(); //constant member function String& MyClass::doSomething() const; Please let me know the reason behind it. Thanks, GG

    Read the article

facebook twitter digg google delicious technorati stumbleupon myspace wordpress linkedin gmail igoogle windows live tumblr viadeo yahoo buzz yahoo mail yahoo bookmarks favorites email print

< Previous Page | 1 2 3 4 5 6 7 8 9 10 11 12  | Next Page >