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  • Allow member to be const while still supporting operator= on the class

    - by LeopardSkinPillBoxHat
    I have several members in my class which are const and can therefore only be initialised via the initialiser list like so: class MyItemT { public: MyItemT(const MyPacketT& aMyPacket, const MyInfoT& aMyInfo) : mMyPacket(aMyPacket), mMyInfo(aMyInfo) { } private: const MyPacketT mMyPacket; const MyInfoT mMyInfo; }; My class can be used in some of our internally defined container classes (e.g. vectors), and these containers require that operator= is defined in the class. Of course, my operator= needs to do something like this: MyItemT& MyItemT::operator=(const MyItemT& other) { mMyPacket = other.mPacket; mMyInfo = other.mMyInfo; return *this; } which of course doesn't work because mMyPacket and mMyInfo are const members. Other than making these members non-const (which I don't want to do), any ideas about how I could fix this?

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  • const return value and template instantiation

    - by Rimo
    From Herb Sutter's GotW #6 Return-by-value should normally be const for non-builtin return types. .... Note: Lakos (pg. 618) argues against returning const value, and notes that it is redundant for builtins anyway (for example, returning "const int"), which he notes may interfere with template instantiation. .... While Sutter seems to disagree on whether to return a const value or non-const value when returning an object of a non-built type by value with Lakos, he generally agrees that returning a const value of a built-in type (e.g const int) is not a good idea. While I understand why that is useless because the return value cannot be modified as it is an rvalue, I cannot find an example of how that might interfere with template instantiation. Please give me an example of how having a const qualifier for a return type might interfere with template instantiation.

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  • g++ linker can't find const member function

    - by Max
    I have a Point class (with integer members x and y) that has a member function withinBounds that is declared like so: bool withinBounds(const Point&, const Point&) const; and defined like this: bool Point::withinBounds(const Point& TL, const Point& BR) const { if(x < TL.getX()) return false; if(x > BR.getX()) return false; if(y < TL.getY()) return false; if(y > BR.getY()) return false; // Success return true; } and then in another file, I call withinBounds like this: Point pos = currentPlayer->getPosition(); if(pos.withinBounds(topleft, bottomright)) { // code block } This compiles fine, but it fails to link. g++ gives me this error: /home/max/Desktop/Development/YARL/yarl/src/GameData.cpp:61: undefined reference to 'yarl::utility::Point::withinBounds(yarl::utility::Point const&, yarl::utility::Point const&)' When I make the function not const, it links fine. Anyone know the reason why? The linker error looks like it's looking for a non-const version of the function, but I don't know why it would.

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  • Is it appropriate to set a value to a "const char *" in the header file

    - by sud
    I have seen people using 2 methods to declare and define char * Medhod-1: The header file has the below const char* COUNTRY_NAME_USA = "USA"; Medhod-2: The header file has the below declaration const char* COUNTRY_NAME_USA; The cpp file has the below defintion : const char* COUNTRY_NAME_USA = "USA"; Is method-2 wrong in some way ? What is the difference between the two ? I understand the difference between "const char * const var" , and "const char * var". If in the above methods if a "const char * const var" is declared and defined in the header as in method 1 will it make sense ?

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  • Simplifying const Overloading?

    - by templatetypedef
    Hello all- I've been teaching a C++ programming class for many years now and one of the trickiest things to explain to students is const overloading. I commonly use the example of a vector-like class and its operator[] function: template <typename T> class Vector { public: T& operator[] (size_t index); const T& operator[] (size_t index) const; }; I have little to no trouble explaining why it is that two versions of the operator[] function are needed, but in trying to explain how to unify the two implementations together I often find myself wasting a lot of time with language arcana. The problem is that the only good, reliable way that I know how to implement one of these functions in terms of the other is with the const_cast/static_cast trick: template <typename T> const T& Vector<T>::operator[] (size_t index) const { /* ... your implementation here ... */ } template <typename T> T& Vector<T>::operator[] (size_t index) { return const_cast<T&>(static_cast<const Vector&>(*this)[index]); } The problem with this setup is that it's extremely tricky to explain and not at all intuitively obvious. When you explain it as "cast to const, then call the const version, then strip off constness" it's a little easier to understand, but the actual syntax is frightening,. Explaining what const_cast is, why it's appropriate here, and why it's almost universally inappropriate elsewhere usually takes me five to ten minutes of lecture time, and making sense of this whole expression often requires more effort than the difference between const T* and T* const. I feel that students need to know about const-overloading and how to do it without needlessly duplicating the code in the two functions, but this trick seems a bit excessive in an introductory C++ programming course. My question is this - is there a simpler way to implement const-overloaded functions in terms of one another? Or is there a simpler way of explaining this existing trick to students? Thanks so much!

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  • C++: combine const with template arguments

    - by awn
    The following example is working when I manualy replace T wirh char *, but why is not working as it is: template <typename T> class A{ public: A(const T _t) { } }; int main(){ const char * c = "asdf"; A<char *> a(c); } When compiling with gcc, I get this error: test.cpp: In function 'int main()': test.cpp:10: error: invalid conversion from 'const char*' to 'char*' test.cpp:10: error: initializing argument 1 of 'A<T>::A(T) [with T = char*]'

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  • C++: get const or non-const reference type from trait

    - by maciekp
    I am writing a functor F which takes function of type void (*func)(T) and func's argument arg. Then functor F calls func with arg. I would like F not to copy arg, just to pass it as reference. But then I cannot simply write "void F(void (*func)(T), T&)" because T could be a reference. So I am trying to write a trait, which allows to get proper reference type of T: T -> T& T& -> T& const T -> const T& const T& -> const T& I come up with something like this: template<typename T> struct type_op { typedef T& valid_ref_type; }; template<typename T> struct type_op<T&> { typedef typename type_op<T>::valid_ref_type valid_ref_type; }; template<typename T> struct type_op<const T> { typedef const T& valid_ref_type; }; template<typename T> struct type_op<const T&> { typedef const T& valid_ref_type; }; Which doesn't work for example for void a(int x) { std::cout << x << std::endl; } F(&a, 7); Giving error: invalid initialization of non-const reference of type ‘int&’ from a temporary of type ‘int’ in passing argument 2 of ‘void f(void (*)(T), typename type_op::valid_ref_type) [with T = int]’ How to get this trait to work?

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  • std::cin >> *aa results in a bus error

    - by Koning Baard XIV
    I have this a class called PPString: PPString.h #ifndef __CPP_PPString #define __CPP_PPString #include "PPObject.h" class PPString : public PPObject { char *stringValue[]; public: char *pointerToCharString(); void setCharString(char *charString[]); void setCharString(const char charString[]); }; #endif PPString.cpp #include "PPString.h" char *PPString::pointerToCharString() { return *stringValue; } void PPString::setCharString(char *charString[]) { *stringValue = *charString; } void PPString::setCharString(const char charString[]) { *stringValue = (char *)charString; } I'm trying to set the stringValue using std::cin: main.cpp PPString myString; myString.setCharString("LOLZ"); std::cout << myString.pointerToCharString() << std::endl; char *aa[1000]; std::cin >> *aa; myString.setCharString(aa); std::cout << myString.pointerToCharString() << std::endl; The first one, which uses a const char works, but the second one, with a char doesn't, and I get this output: copy and paste from STDOUT LOLZ im entering a string now... Bus error where the second line is what I entered, followed by pressing the return key. Can anyone help me fixing this? Thanks...

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  • I can't get that `bus error` to stop sucking.

    - by Koning Baard XIV
    I have this a class called PPString: PPString.h #ifndef __CPP_PPString #define __CPP_PPString #include "PPObject.h" class PPString : public PPObject { char *stringValue[]; public: char *pointerToCharString(); void setCharString(char *charString[]); void setCharString(const char charString[]); }; #endif PPString.cpp #include "PPString.h" char *PPString::pointerToCharString() { return *stringValue; } void PPString::setCharString(char *charString[]) { *stringValue = *charString; } void PPString::setCharString(const char charString[]) { *stringValue = (char *)charString; } I'm trying to set the stringValue using std::cin: main.cpp PPString myString; myString.setCharString("LOLZ"); std::cout << myString.pointerToCharString() << std::endl; char *aa[1000]; std::cin >> *aa; myString.setCharString(aa); std::cout << myString.pointerToCharString() << std::endl; The first one, which uses a const char works, but the second one, with a char doesn't, and I get this output: copy and paste from STDOUT LOLZ im entering a string now... Bus error where the second line is what I entered, followed by pressing the return key. Can anyone help me fixing this? Thanks...

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  • Passing const CName as this argument discards qualifiers

    - by Geno Diaz
    I'm having trouble with passing a constant class through a function. // test the constructors auto CName nameOne("Robert", "Bresson"); const CName nameTwo = nameOne; auto CName nameThree; // display the contents of each newly-constructed object... // should see "Robert Bresson" cout << "nameOne = "; nameOne.WriteFullName(); cout << endl; // should see "Robert Bresson" again cout << "nameTwo = "; nameTwo.WriteFullName(); cout << endl; As soon as the compiler hits nameTwo.WriteFullName() I get the error of abandoning qualifiers. I know that the class is a constant however I can't figure out how to work around it. The function is in a header file written as so: void const WriteFullName(ostream& outstream = cout) { outstream << m_first << ' ' << m_last; } I receive this error when const is put in back of the function header main.cpp:(.text+0x51): undefined reference to CName::CName()' main.cpp:(.text+0x7c): undefined reference toCName::WriteFullName(std::basic_ostream &) const' main.cpp:(.text+0xbb): undefined reference to CName::WriteFullName(std::basic_ostream<char, std::char_traits<char> >&) const' main.cpp:(.text+0xf7): undefined reference toCName::WriteFullName(std::basic_ostream &) const' main.cpp:(.text+0x133): undefined reference to operator>>(std::basic_istream<char, std::char_traits<char> >&, CName&)' main.cpp:(.text+0x157): undefined reference tooperator<<(std::basic_ostream &, CName const&)' main.cpp:(.text+0x1f4): undefined reference to operator<<(std::basic_ostream<char, std::char_traits<char> >&, CName const&)' main.cpp:(.text+0x22b): undefined reference tooperator<<(std::basic_ostream &, CName const&)' main.cpp:(.text+0x25f): undefined reference to operator<<(std::basic_ostream<char, std::char_traits<char> >&, CName const&)' main.cpp:(.text+0x320): undefined reference tooperator<<(std::basic_ostream &, CName const&)' main.cpp:(.text+0x347): undefined reference to `operator(std::basic_istream &, CName&)'

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  • Why is passing a string literal into a char* arguament only sometimes a compiler error?

    - by Brian Postow
    I'm working in a C, and C++ program. We used to be compiling without the make-strings-writable option. But that was getting a bunch of warnings, so I turned it off. Then I got a whole bunch of errors of the form "Cannot convert const char* to char* in argmuent 3 of function foo". So, I went through and made a whole lot of changes to fix those. However, today, the program CRASHED because the literal "" was getting passed into a function that was expecting a char*, and was setting the 0th character to 0. It wasn't doing anything bad, just trying to edit a constant, and crashing. My question is, why wasn't that a compiler error? In case it matters, this was on a mac compiled with gcc-4.0.

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  • Python to C/C++ const char question

    - by tsukemonoki
    I am extending Python with some C++ code. One of the functions I'm using has the following signature: int PyArg_ParseTupleAndKeywords(PyObject *arg, PyObject *kwdict, char *format, char **kwlist, ...); (link: http://docs.python.org/release/1.5.2p2/ext/parseTupleAndKeywords.html) The parameter of interest is kwlist. In the link above, examples on how to use this function are given. In the examples, kwlist looks like: static char *kwlist[] = {"voltage", "state", "action", "type", NULL}; When I compile this using g++, I get the warning: warning: deprecated conversion from string constant to ‘char*’ So, I can change the static char* to a static const char*. Unfortunately, I can't change the Python code. So with this change, I get a different compilation error (can't convert char** to const char**). Based on what I've read here, I can turn on compiler flags to ignore the warning or I can cast each of the constant strings in the definition of kwlist to char *. Currently, I'm doing the latter. What are other solutions? Sorry if this question has been asked before. I'm new.

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  • berkeley DB: can't compile c++ codes

    - by Brian
    When I compiled the sample codes of C++, I got following info: c++ excxx_example_database_read.cpp -o dbApp -I /usr/local/BerkeleyDB.5.0/include/ Undefined symbols: "Dbt::Dbt(void*, unsigned int)", referenced from: show_vendor(MyDb&, char const*)in ccnaWItX.o show_item(MyDb&, MyDb&, std::basic_string<char, std::char_traits<char>, std::allocator<char> >&)in ccnaWItX.o "Dbc::get(Dbt*, Dbt*, unsigned int)", referenced from: show_all_records(MyDb&, MyDb&) in ccnaWItX.o show_item(MyDb&, MyDb&, std::basic_string<char, std::char_traits<char>, std::allocator<char> >&)in ccnaWItX.o show_item(MyDb&, MyDb&, std::basic_string<char, std::char_traits<char>, std::allocator<char> >&)in ccnaWItX.o "Dbc::close()", referenced from: show_all_records(MyDb&, MyDb&) in ccnaWItX.o show_all_records(MyDb&, MyDb&) in ccnaWItX.o show_all_records(MyDb&, MyDb&) in ccnaWItX.o show_item(MyDb&, MyDb&, std::basic_string<char, std::char_traits<char>, std::allocator<char> >&)in ccnaWItX.o show_item(MyDb&, MyDb&, std::basic_string<char, std::char_traits<char>, std::allocator<char> >&)in ccnaWItX.o show_item(MyDb&, MyDb&, std::basic_string<char, std::char_traits<char>, std::allocator<char> >&)in ccnaWItX.o "Dbt::~Dbt()", referenced from: show_vendor(MyDb&, char const*)in ccnaWItX.o show_vendor(MyDb&, char const*)in ccnaWItX.o show_vendor(MyDb&, char const*)in ccnaWItX.o show_vendor(MyDb&, char const*)in ccnaWItX.o show_all_records(MyDb&, MyDb&) in ccnaWItX.o show_all_records(MyDb&, MyDb&) in ccnaWItX.o show_all_records(MyDb&, MyDb&) in ccnaWItX.o show_all_records(MyDb&, MyDb&) in ccnaWItX.o show_item(MyDb&, MyDb&, std::basic_string<char, std::char_traits<char>, std::allocator<char> >&)in ccnaWItX.o show_item(MyDb&, MyDb&, std::basic_string<char, std::char_traits<char>, std::allocator<char> >&)in ccnaWItX.o show_item(MyDb&, MyDb&, std::basic_string<char, std::char_traits<char>, std::allocator<char> >&)in ccnaWItX.o show_item(MyDb&, MyDb&, std::basic_string<char, std::char_traits<char>, std::allocator<char> >&)in ccnaWItX.o "Db::~Db()", referenced from: MyDb::~MyDb() in ccnaWItX.o MyDb::~MyDb() in ccnaWItX.o "typeinfo for DbException", referenced from: GCC_except_table3 in ccnaWItX.o GCC_except_table4 in ccnaWItX.o GCC_except_table5 in ccnaWItX.o GCC_except_table6 in ccnaWItX.o __ZTI11DbException$non_lazy_ptr in ccnaWItX.o "DbException::~DbException()", referenced from: __ZN11DbExceptionD1Ev$non_lazy_ptr in ccnaWItX.o "MyDb::close()", referenced from: MyDb::~MyDb() in ccnaWItX.o "MyDb::MyDb(std::basic_string<char, std::char_traits<char>, std::allocator<char> >&, std::basic_string<char, std::char_traits<char>, std::allocator<char> >&, bool)", referenced from: _main in ccnaWItX.o _main in ccnaWItX.o _main in ccnaWItX.o "Dbt::Dbt()", referenced from: show_vendor(MyDb&, char const*)in ccnaWItX.o show_all_records(MyDb&, MyDb&) in ccnaWItX.o show_all_records(MyDb&, MyDb&) in ccnaWItX.o show_item(MyDb&, MyDb&, std::basic_string<char, std::char_traits<char>, std::allocator<char> >&)in ccnaWItX.o "DbException::get_errno() const", referenced from: show_vendor(MyDb&, char const*)in ccnaWItX.o show_all_records(MyDb&, MyDb&) in ccnaWItX.o show_item(MyDb&, MyDb&, std::basic_string<char, std::char_traits<char>, std::allocator<char> >&)in ccnaWItX.o _main in ccnaWItX.o "DbException::DbException(DbException const&)", referenced from: show_vendor(MyDb&, char const*)in ccnaWItX.o show_all_records(MyDb&, MyDb&) in ccnaWItX.o show_item(MyDb&, MyDb&, std::basic_string<char, std::char_traits<char>, std::allocator<char> >&)in ccnaWItX.o ld: symbol(s) not found collect2: ld returned 1 exit status I have no idea what is the problem. Please help!

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  • How to provide stl like container with public const iterator and private non-const iterator?

    - by WilliamKF
    Hello, I am deriving a class privately from std::list and wish to provide public begin() and end() for const_iterator and private begin() and end() for just plain iterator. However, the compiler is seeing the private version and complaining that it is private instead of using the public const version. I understand that C++ will not overload on return type (in this case const_iterator and iterator) and thus it is choosing the non-const version since my object is not const. Short of casting my object to const before calling begin() or not overloading the name begin is there a way to accomplish this? I would think this is a known pattern that folks have solved before and would like to follow suit as to how this is typically solved. class myObject; class myContainer : private std::list<myObject> { public: typedef std::list<myObject>::const_iterator myContainer::const_iterator; private: typedef std::list<myObject>::iterator myContainer::iterator; public: myContainer::const_iterator begin() const { return std::list<myObject>::begin(); } myContainer::const_iterator end() const { return std::list<myObject>::end(); } private: myContainer::iterator begin() { return std::list<myObject>::begin(); } myContainer::iterator end() { return std::list<myObject>::end(); } }; void myFunction(myContainer &container) { myContainer::const_iterator aItr = container.begin(); myContainer::const_iterator aEndItr = container.end(); for (; aItr != aEndItr; ++aItr) { const myObject &item = *aItr; // Do something const on container's contents. } } The error from the compiler is something like this: ../../src/example.h:447: error: `std::_List_iterator<myObject> myContainer::begin()' is private caller.cpp:2393: error: within this context ../../src/example.h:450: error: `std::_List_iterator<myObject> myContainer::end()' is private caller.cpp:2394: error: within this context Thanks. -William

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  • C function const multidimensional-array argument strange warning

    - by rogi
    Ehllo, I'm getting some strange warning about this code: typedef double mat4[4][4]; void mprod4(mat4 r, const mat4 a, const mat4 b) { /* yes, function is empty */ } int main() { mat4 mr, ma, mb; mprod4(mr, ma, mb); } gcc output as follows: $ gcc -o test test.c test.c: In function 'main': test.c:13: warning: passing argument 2 of 'mprod4' from incompatible pointer type test.c:4: note: expected 'const double (*)[4]' but argument is of type 'double (*)[4]' test.c:13: warning: passing argument 3 of 'mprod4' from incompatible pointer type test.c:4: note: expected 'const double ()[4]' but argument is of type 'double ()[4]' defining the function as: void mprod4(mat4 r, mat4 a, mat4 b) { } OR defining matrices at main as: mat4 mr; const mat4 ma; const mat4 mb; OR calling teh function in main as: mprod4(mr, (const double(*)[4])ma, (const double(*)[4])mb); OR even defining mat4 as: typedef double mat4[16]; make teh warning go away. Wat is happening here? Am I doing something invalid? gcc version is 4.4.3 if relevant. Thanks for your attention.

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  • Detecting const-ness of nested type

    - by Channel72
    Normally, if I need to detect whether a type is const I just use boost::is_const. However, I ran into trouble when trying to detect the const-ness of a nested type. Consider the following traits template, which is specialized for const types: template <class T> struct traits { typedef T& reference; }; template <class T> struct traits<const T> { typedef T const& reference; }; The problem is that boost::is_const doesn't seem to detect that traits<const T>::reference is a const type. For example: std::cout << std::boolalpha; std::cout << boost::is_const<traits<int>::reference>::value << " "; std::cout << boost::is_const<traits<const int>::reference>::value << std::endl; This outputs: false false Why doesn't it output false true?

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  • scanf("%d", char*) - char-as-int format string?

    - by SF.
    What is the format string modifier for char-as-number? I want to read in a number never exceeding 255 (actually much less) into an unsigned char type variable using sscanf. Using the typical char source[] = "x32"; char separator; unsigned char dest; int len; len = sscanf(source,"%c%d",&separator,&dest); // validate and proceed... I'm getting the expected warning: argument 4 of sscanf is type char*, int* expected. As I understand the specs, there is no modifier for char (like %sd for short, or %lld for 64-bit long) is it dangerous? (will overflow just overflow (roll-over) the variable or will it write outside the allocated space?) is there a prettier way to achieve that than allocating a temporary int variable? ...or would you suggest an entirely different approach altogether?

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  • Returning a C++ reference in a const member functionasses

    - by Chris Kaminski
    A have a class hierarchy that looks somethign like this: class AbstractDataType { public: virtual int getInfo() = 0; }; class DataType: public AbstractDataType { public: virtual int getInfo() { }; } class Accessor { DataType data; public: const AbstractDataType& getData() const { return(data); } } Well, GCC 4.4 reports: In member function ‘const AbstractDataType& Accessor::getData() const’: error: invalid initialization of reference of type ‘const AbstractDataType&’ from expression of type ‘const DataType’ Where am I going wrong - is this a case where I MUST use a pointer?

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  • C++: Why does gcc prefer non-const over const when accessing operator[]?

    - by JonasW
    This question might be more appropriately asked regarding C++ in general, but as I am using gcc on linux that's the context. Consider the following program: #include <iostream> #include <map> #include <string> using namespace std; template <typename TKey, typename TValue> class Dictionary{ public: map<TKey, TValue> internal; TValue & operator[](TKey const & key) { cout << "operator[] with key " << key << " called " << endl; return internal[key]; } TValue const & operator[](TKey const & key) const { cout << "operator[] const with key " << key << " called " << endl; return internal.at(key); } }; int main(int argc, char* argv[]) { Dictionary<string, string> dict; dict["1"] = "one"; cout << "first one: " << dict["1"] << endl; return 0; } When executing the program, the output is: operator[] with key 1 called operator[] with key 1 called first one: one What I would like is to have the compiler choose the operator[]const method instead in the second call. The reason is that without having used dict["1"] before, the call to operator[] causes the internal map to create the data that does not exist, even if the only thing I wanted was to do some debugging output, which of course is a fatal application error. The behaviour I am looking for would be something like the C# index operator which has a get and a set operation and where you could throw an exception if the getter tries to access something that doesn't exist: class MyDictionary<TKey, TVal> { private Dictionary<TKey, TVal> dict = new Dictionary<TKey, TVal>(); public TVal this[TKey idx] { get { if(!dict.ContainsKey(idx)) throw KeyNotFoundException("..."); return dict[idx]; } set { dict[idx] = value; } } } Thus, I wonder why the gcc prefers the non-const call over the const call when non-const access is not required.

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  • Cast vector<T> to vector<const T>

    - by user345386
    I have a member variable of type vector (where is T is a custom class, but it could be int as well.) I have a function from which I want to return a pointer to this vector, but I don't want the caller to be able to change the vector or it's items. So I want the return type to be const vector* None of the casting methods I tried worked. The compiler keeps complaining that T is not compatible with const T. Here's some code that demonstrates the gist of what I'm trying to do; vector<int> a; const vector<const int>* b = (const vector<const int>* ) (&a); This code doesn't compile for me. Thanks in advance!

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  • Returning char* in function

    - by Devel
    I have function: char *zap(char *ar) { char pie[100] = "INSERT INTO test (nazwa, liczba) VALUES ('nowy wpis', '"; char dru[] = "' )"; strcat(pie, ar); strcat(pie, dru); return pie; } and in main there is: printf("%s", zap( argv[1] ) ); When compiling I get the warning: test.c: In function ‘zap’: test.c:17: warning: function returns address of local variable How should I return char* propertly?

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  • Specializing function template for both std::string and char*

    - by sad_man
    As the title says I want to specialize a function template for both string and char pointer, so far I did this but I can not figure out passing the string parameters by reference. #include <iostream> #include <string> template<typename T> void xxx(T param) { std::cout << "General : "<< sizeof(T) << std::endl; } template<> void xxx<char*>(char* param) { std::cout << "Char ptr: "<< strlen(param) << std::endl; } template<> void xxx<const char* >(const char* param) { std::cout << "Const Char ptr : "<< strlen(param)<< std::endl; } template<> void xxx<const std::string & >(const std::string & param) { std::cout << "Const String : "<< param.size()<< std::endl; } template<> void xxx<std::string >(std::string param) { std::cout << "String : "<< param.size()<< std::endl; } int main() { xxx("word"); std::string aword("word"); xxx(aword); std::string const cword("const word"); xxx(cword); } Also template<> void xxx<const std::string & >(const std::string & param) thing just does not working. If I rearranged the opriginal template to accept parameters as T& then the char * is required to be char * & which is not good for static text in code. Please help !

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  • const object and const constructor

    - by Muhammad alaa
    Is there any way to know if an object is a const object or regular object, for instance consider the following class class String { String(const char* str); }; if user create a const object from String then there is no reason to copy the passed native string and that because he will not make any manipulation on it, the only thing he will do is get string size, string search and other functions that will not change the string.

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