If so please share the solution with us and mark the right answers. I feel stupid for asking, but I suppose I should not delete an upvoted question. {
This seems like one of them. How to pass a constant array literal to a function that takes a pointer without using a variable C/C++? What are the differences between a pointer variable and a reference variable? How long does it take to fill up the tank? rev2022.12.9.43105. Is it correct to say "The glue on the back of the sticker is dying down so I can not stick the sticker to the wall"? Not the answer you're looking for? 1> Types pointed to are unrelated; conversion requires reinterpret_cast, C-style cast or function-style cast 1>AssemblyInfo.cpp 1>Generating Code. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. I have a bunch of function objects, that I need to cast to a coomon type: The case if specializing by size_t does not compile. One last thing about C pointers: confused about what this snippet of code will do? Formally calling via the pointer casted to different function type is Undefined Behavior (by C++11 5.2.10/6). But the Posix round-trip would presumably work also on such architecture, unless the data address space was much smaller than the instruction address space. Why is Singapore currently considered to be a dictatorial regime and a multi-party democracy by different publications? In practice you're casting away a function result of type int, that would be returned in a register. I cast a, @St.Antario: That's true.. Why was USB 1.0 incredibly slow even for its time? Explanation Unlike static_cast, but like const_cast, the reinterpret_cast expression does not compile to any CPU instructions (except when converting between integers and pointers or on obscure architectures where pointer representation depends on its type). The result is that of *reinterpret_cast
(p) where p is a pointer to x of type pointer to T1. This is one of the most complex and dangerous casting operators available in C++. It can therefore be used as a replacement for other casts in some instances, but can be extremely dangerous because . However, function type, @St.Antario From 4.3/1: "An lvalue of function type T can be converted to a prvalue of type pointer to T. The result is a pointer to the function.". 1. How can I cast "const void*" to the function pointer in C++11? reinterpret_cast is a type of casting operator used in C++. The drawback of the "cast the result" method is that if you get it wrong the results are undefined. Give me an example of two pointers that are not the same size. C++ supports four types of casting: 1.Static Cast 2. A function type is not the same as a pointer to function type. The result is that of *reinterpret_cast<T2 *>(p)where pis a pointer to xof type "pointer to T1". The definition of compatible is somewhat complicated. In practice you're casting away a function result of type int, that would be returned in a register. If parameters/return value are of the same size there are no stack corruption. Mathematica cannot find square roots of some matrices? Where to implement tolerance to decide when to detect tochscreen press events and move events in Qt? Why the size of a pointer to a function is different from the size of a pointer to a member function? Are defenders behind an arrow slit attackable? : I am guessing that you have a bunch of function objects you want to store in a collection. Member definition of partially specialized classes, How to explicitly call a conversion function whose conversion-type-id contains a placeholder specifier, Examples of frauds discovered because someone tried to mimic a random sequence. The reinterpret_cast operator performs potentially unsafe type casts. I gather It's clear. Is the program ill-formed and the compilers fail to diagnose it or is the program well-formed? Does balls to the wall mean full speed ahead or full speed ahead and nosedive? reinterpret_cast<T> (v) v 2 reinterpret_cast () ( long Sun C++ ) A value of integral or enumeration type to a pointer. Also you have the specialized B constructor take a function, when I think you want it to take a function. How else to achieve "templated function pointers"? C++ intchar,c++,pointers,casting,C++,Pointers,Casting,ifstreamint int myInt = 0; fileStream.read(reinterpret_cast<char*>(&myInt), sizeof(int)); int-myInt=0 readreinterpret_cast&myIntsizeofint reinterpret\u cast reinterpret_cast . Calling C++ member functions via a function pointer, C++ lambda with captures as a function pointer, Resolving ambiguous overload on function pointer and std::function for a lambda using + (unary plus), How to make a function return a pointer to a function? Were sorry. reinterpret_cast(x) is equivalent to *reinterpret_cast(&x). QSocketNotifier: Can only be used with threads started with QThread error, error: expected class-name before { token with templates, How to change the "Inherited Values" in Property Page in Visual Studio 2012 Express. Why does my stock Samsung Galaxy phone/tablet lack some features compared to other Samsung Galaxy models? By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, C++ allows you to shoot you in the foot in many interesting ways, and if you're lucky the compiler will give you a warning about it. -- with that you can store any type of function objects you like. 7 A pointer to an object can be explicitly converted to a pointer to an object of different type converting an rvalue of type ? - reinterpret_cast is a keyword. constexpr and initialization of a static const void pointer with reinterpret cast, which compiler is right? How to check if a string has a valid file path or directory path format in unmanaged C++ code? @PeteBecker It doesn't seem to make a difference to the compilers. Can Reinterpret_cast return null? It is most often used to cast a pointer to a different pointer type. requirements of T2 are no stricter than those of T1) and back to its original type yields the original pointer value. Copyright 2022 www.appsloveworld.com. In the last available draft for C++0X, the reinterpret_castbetween function pointers and objects pointers is conditionally supported. forward declaration of class using templates, Characters extracted by istream >> double. Thanks for contributing an answer to Stack Overflow! pfnFoo = reinterpret_cast<FN_FOO> (&Derived::Foo); You have a number of misconceptions and other problems as well. ?pointer to T1? to the type ? Is it cheating if the proctor gives a student the answer key by mistake and the student doesn't report it? Solution 3. const_cast const C++ cast const ( reinterpret_cast ) stackoverflow const_cast const const const std::tr1::function -> std::tr1::function. . Are these two types the same types of not? reinterpret_cast is a type of casting operator used in C++. The content you requested has been removed. Casting a pointer to a different pointer and back is usually safe and yields the original value. Can I legally cast a member function pointer to a function pointer? Formally calling via the pointer casted to different function type is Undefined Behavior (by C++11 5.2.10/6). Find centralized, trusted content and collaborate around the technologies you use most. class B : private A
Not the answer you're looking for? (GCC requires the -pedantic-errors flag to enforce that, though.). Can I cast function pointer void* to std::function? However, I can use the plain-old-C-style cast and the code compiles and works. What happens if you score more than 99 points in volleyball? Help us identify new roles for community members, Proposing a Community-Specific Closure Reason for non-English content, Calling derived class through base class function pointer. How to static cast throwing function pointer to noexcept in C++17? However, ildjarn's point is still valid -- if you would share what you are trying to do, we may be able to suggest a better, type-safe method. In the best case, if the object does not implement the requested interface, the call simply fails. Function pointers, conversions and comparisonsI hope you found a solution that worked for you :) The Content (except music & images) is licensed under (https. Does balls to the wall mean full speed ahead or full speed ahead and nosedive? Does aliquot matter for final concentration? It is used to convert a pointer of some data type into a pointer of another data type, even if the data types before and after conversion are different. Can const member function return a non-const pointer to a data member? . Passing capturing lambda as function pointer, "unpacking" a tuple to call a matching function pointer. reinterpret_cast<type> (expr) The reinterpret_cast operator changes a pointer to any other type of pointer. A glvalue of type T1, designating an object x, can be cast to the type reference to T2 if an expression of type pointer to T1 can be explicitly converted to the type pointer to T2 using a reinterpret_cast. public:
A pointer to a function can be explicitly converted to a pointer to a function of a different type. Passing a pointer to a member function as a template argument. . Making statements based on opinion; back them up with references or personal experience. Did neanderthals need vitamin C from the diet? reinterpret_cast<Thing*>(it); you are telling the compiler to literally reinterpret the itobject as a pointer. A C-style cast is defined as the first of the following which succeeds: const_cast. Function does not change passed pointer C++, Disambiguate overloaded member function pointer being passed as template parameter, Determine if Type is a pointer in a template function. You can explicitly perform the following conversions: A pointer to any integral type large enough to hold it. The C++ restriction is presumably in support of Harvard architecture machines, where instructions are not retrieved via the same bus and memory as ordinary data. A glvalue of type T1, designating an object x, can be cast to the type reference to T2 if an expression of type pointer to T1 can be explicitly converted to the type pointer to T2 using a reinterpret_cast. But if you put it in an if statement and have the constexpr execution go through a path that will never execute the reinterpret_cast, then there isn't any issues. Note that if that make sense or not will depend on the target more than the compiler: a portable compiler like gcc will have a behavior imposed by the target architecture and possibly ABI. Connect and share knowledge within a single location that is structured and easy to search. A tag already exists with the provided branch name. Why should I use a pointer rather than the object itself? I.e. You cannot cast away a const or volatile qualification. Youll be auto redirected in 1 second. why can't I cast a pointer to Derived class member function to the same but of class Base? I don't see any rule in the standard allowing this conversion. The result is that of *reinterpret_cast(p) where p is a pointer to x of type pointer to T1. The only contexts that prevent function type decay are unary & operator, sizeof operator and some others. First of all why such reinterpret_cast convertion permitted? A dynamic_cast performs casts on polymorphic types and can cast a A* pointer into a B* pointer only if the object being pointed to actually is a B object. What are the differences between a pointer variable and a reference variable? C-style pointer casting detected. You cannot cast away a const or volatile qualification. (C++). All rights reserved. The " reinterpret_cast " operator can convert any type of variable to fundamentally different type. But the Posix round-trip would presumably work also on such architecture, unless the data address space was much smaller than the instruction address space. What do you mean "not all pointers are the same size"? Why does the distance from light to subject affect exposure (inverse square law) while from subject to lens does not? If you put the reinterpret_cast in a place that will always get executed, then when the code is actually executed in the compiler then it will throw errors even with VC. For conversions between object pointer types and function pointer types, the C++11 standard says (5.2.10 [expr . generic member function pointer as a template parameter, Get a pointer to object's member function. It is a compile-time cast. C style casts in C++ will attempt a static_cast first and only perform a reinterpret_cast if a static cast cannot be performed. Making statements based on opinion; back them up with references or personal experience. reinterpret_cast is not an exception, which means that every time you specify function name as an operand, it gets implicitly converted to function pointer type. The reinterpret_cast expression circumvents the C++ type system, so the compiler will not catch this error. Accessing the result of this cast violates strict aliasing and causes undefined behavior, as usual. Your syntax for specialization is a bit off, try. Sander's answer. So about the worst that can happen when you call via the casted pointer, is that contrary to the compiler's expectations a register has changed value. reinterpret_cast member function pointer to void(*&)(). Reinterpret Cast Static Cast: This is the simplest type of cast that can be used. It does not check if the pointer type and data pointed by the pointer is same or not. boost::any
When the migration is complete, you will access your Teams at stackoverflowteams.com, and they will no longer appear in the left sidebar on stackoverflow.com.. The reinterpret_cast operator produces a value of a new type that has the same bit pattern as its argument. You can explicitly perform the following conversions: A pointer to any integral type large enough to hold it. What is a smart pointer and when should I use one? In this case, the program might print a, but in many cases it will print something.. Why is there a performance warning on cast pointer to bool? In other words, reinterpret_cast(x) performs type punning on the pointer itself. In C++, is it allowed to cast a function pointer to one that gets as a parameter a pointer to a base or derived class? Member function pointers can not be reinterpret_cast to function pointers. -. And not all pointers are the same size. Check your email for updates. Dynamic Cast 3. The fact that the implementations you have seen happen to have pointers of, the same size does not make that universally true. What is C style cast? While we are at it, we can replace the C-cast with the proper C++ cast, which in this case is reinterpret_cast: constexpr auto FOO = reinterpret_cast<uint8*> (0xBAD50BAD); constexpr auto BAR = reinterpret_cast<S*> (FOO); Sadly, this won't compile, because reinterpret_cast s are not allowed in constant expressions by the standard. What does"one-past-the-last-element" mean in vectors? - type is a pointer reinterpreted as. Cast pointer to member function to intptr_t, Calling C++ member functions via a function pointer, Disambiguate overloaded member function pointer being passed as template parameter, C++ function pointer (class member) to non-static member function. Pick one. But it might not be a pointer at all -- it might be a 50-byte struct, for all you know! Accessing the result of this cast violates strict aliasing and causes undefined behavior, as usual. made the recommended changes Syntax : : A( []()->void* { return reinterpret_cast(f()); } ). How to judge whether a project is a c or c++ project? It also allows casting from pointer to an integer type and vice versa. Except that converting a prvalue of type "pointer to T1" to the type "pointer to T2" (where T1 and T2 are function types) and back to its original type yields the original pointer value, the result of such a pointer conversion is unspecified. How to understand libcxx's implementation of make_integer_sequence? functions (C++ only) Example using the exception handling functions (C++ only) Preprocessor directives . Why does this work? However GCC, Clang and MSVC seem to agree that casting a member function pointer to a reference to function pointer is ok. See the following example: This program compiles on all three compilers, but fails to compile on all (with pedantic flags) when the out-commented line is used instead of the previous one. How to do a function pointer cast without a typedef? I guess I have two questions:- First, there are a number of compilers available for Windows and Linux. The C and C++, specifications are very careful about that. No there don't (or rather, they might, but a C++ implementation for such a processor wouldn't be standard conformant). Asking for help, clarification, or responding to other answers. Since reinterpret_castbetween pointers to object types (in your case, between pointers to pointers (to [member] functions)) is always allowed, it's also allowed in your case. Use unsafe code to reinterpret pointers. Wrong - you need to reinterpret p, pointer value p contains, not the address of pointer variable itself. Help us identify new roles for community members, Proposing a Community-Specific Closure Reason for non-English content. In other words, reinterpret_cast(x) performs type punning on the pointer itself. Accessing the result of this cast violates strict aliasing and causes undefined behavior, as usual. The reinterpret_cast operator converts a null pointer value to the null pointer value of the destination type. In that case, the first sizeof (Thing*)bytes of it will absolutely not happen to point at anything sensible. My example did show ways you could store a bunch of std::function objects of different type in a single collection. However, they do have drawbacks -- strong enough ones that I would tend to avoid them if possible. reinterpret_cast<T&> (x) is equivalent to *reinterpret_cast<T*> (&x). Leonidas' answer. "expected initializer before '<' token" attempting template member specialization, Handling invalid input in input stream operator >>, reinterpret_cast(37)' is not a constant expression, How do I catch c0000005 exception from native dll in c#, Function returning value vs modifying value passed by reference. A static_cast may change the value of the pointer in the case of multiple inheritance (or when casting an interface to a concrete type), this offset calculation may involve an extra machine instruction. There do exist processors on. . Const Cast 4. Ready to optimize your JavaScript with Rust? return reinterpret_cast<QTimerPrivate *>(qGetPtrHelper (d_ptr)); clang diagnostic pop } inline const QTimerPrivate* d_func() const noexcept { clang diagnostic push return reinterpret_cast [.] Site design / logo 2022 Stack Exchange Inc; user contributions licensed under CC BY-SA. It is used to convert one pointer of another pointer of any type, no matter either the class is related to each other or not. This cast operator can also convert variable into totally incompatible type too. Where is it documented? However, if you disable the warnings or errors in any way, for example by using. The effect of calling a function through a pointer to a function type that is not the same as the type used in the definition of the function is undefined. (int*)p is a C-style cast, which is in this case resolved to reinterpret_cast<int*>(const_cast<char*>(p)). Function multiple definition linker error building on GCC - Makefile issue. Is copy constructor called if assignment operator wasn't defined? C++ may have a sharp edge, or two. Many Git commands accept both tag and branch names, so creating this branch may cause unexpected behavior. std:: static_pointer_cast, std:: dynamic_pointer_cast, std:: const_pointer_cast, std:: reinterpret_pointer_cast From cppreference.com < cpp | memory | shared ptr C++ Compiler support Freestanding and hosted Language Standard library Standard library headers Named requirements Feature test macros (C++20) Language support library We do not currently allow content pasted from ChatGPT on Stack Overflow; read our policy here. Connecting three parallel LED strips to the same power supply. this is trivial for compilers targeting any normal modern cpu, including x86 with a flat memory model (no segmentation); pointers in asm are just integers kept in the same registers as data. How to define a function pointer pointing to a static member function? reinterpret_cast, then const_cast. Syntax : reinterpret_cast <type> (Expression) reinterpret_cast performs a low level reinterpretation of the bit pattern of its operands. Not only this, with function pointers and void pointers, it is possible to use qsort for any data type. GCC Warns About Function Pointer to Object Pointer Cast. Reinterpreting memory is only legal . Here: Cast pointer to member function to intptr_t, Overloading type cast operator, to cast to a pointer to function. Is there any need to make an integer literal unsigned? I thought such conversion is ill-formed. static_cast (though ignoring access restrictions) static_cast (see above), then const_cast. You also forgot the virtual key on the function GetFoo and a lot of semicolons. You cannot cast away a const or volatile qualification. The function is expecting p to be pointing to a sequence of bytes that represents 5 integers. The reinterpret_cast operator produces a value of a new type that has the same bit pattern as its argument. How does legislative oversight work in Switzerland when there is technically no "opposition" in parliament? By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. Another practical consideration: C++ does not support casting between function and data pointers, but Posix effectively requires cast to void* and back to work OK. Is void *function() a pointer to function or a function returning a void*? The downsides to this are that some (rare) environments don't support StructLayout (eg Flash builds in Unity3D) and that . The reinterpret_cast allows the pointer to be treated as an integral . Another practical consideration: C++ does not support casting between function and data pointers, but Posix effectively requires cast to void* and back to work OK. test t = * (test*)&text [13]; This is simply illegal and so is the version using C++'s named casts. I can't even use reinterpret_cast to convert C++ member function pointer to C function pointer, but I have . Passing a pointer to a class member function as a parameter, Cannot use pointer to public member function that comes from a private base, Explicit void pointer as function parameter, Using condition variable in a producer-consumer situation. class B
Connect and share knowledge within a single location that is structured and easy to search. Connecting three parallel LED strips to the same power supply. which a "char *" and an "int *" are different sizes. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. Stephan Bergmann via Phabricator via cfe-commits Thu, 28 Dec 2017 04:50:43 -0800. sberg updated this revision to Diff 128289. sberg added a comment. B(const function & f)
Now the problem is to set the self pointer after constructing a node.self To achieve that i am using reinterpret_cast:reinterpret_cast void createNodeX_children(NodeX *nodex) { // create childY nodex->childY = make_unique<NodeY>(); // . Sorry for being a bit harsh, but for the love of silicon, write C or write good, modern C++. Red herring. Oh that was an obvious solution. I'm very interested your issue, did you solve your problem? Two string literals have the same pointer value. Is there a way to "reinterpret_cast" function objects? unsigned char* x = reinterpret_cast<unsigned char*> (p); > double *z= reinterpret_cast<double*> (&x); Again - here you takes an address of you local variable x, not the value it contains. . Did neanderthals need vitamin C from the diet? This C function uses the void pointer to cast into a C++ instance pointer, from which a member function call can be made. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. All rights reserved. Why can I access a derived private member function via a base class pointer to a derived object? (That vtable itself is globally accessible at runtime and contains pointers to all virtual functions which that class contains. Was the ZX Spectrum used for number crunching? Below C++ program demonstrates the use of reinterpret_cast to reinterpret the bit pattern. How to guarantee copy elision with std::variant? From [expr.reinterpret.cast].6 (emphasis mine):. If the latter, what is the exact conversion sequence, where does the standard allow it and can the function pointer be converted back to the original type in order to call it or is the use of the reference for initialization of y already undefined behavior? p . The reinterpret_cast operator produces a value of a new type that has the same bit pattern as its argument. Here's 3 that aren't the same size in VC++ 2010: While it is true that all pointers-to-members are of oddball sizes, you can't really store a pointer-to-member-function in a void*. To learn more, see our tips on writing great answers. Comparison is always false due to limited range with templates. HolyBlackCat65903 Source: stackoverflow.com Since reinterpret_cast between pointers to object types (in your case, between pointers to pointers (to [member] functions)) is always allowed, it's also allowed in your case. In C, we can use function pointers to avoid code redundancy. In the worst case, the function succeeds and you have a mismatched pointer. [PATCH] D40720: No -fsanitize=function warning when calling noexcept function through non-noexcept pointer in C++17. I have a bunch of function objects, not function pointers, that I need to cast to a coomon type: function, function, function. Cast pointer to member function to normal pointer. I don't see any rule in the standard allowing this conversion. why can't I cast a pointer to Derived class member function to the same but of class Base? ReInterpret Cast ( reinterpret_cast) is a cast operator that converts a pointer of some data type into a pointer of another data type, even if the the data types before and after conversion are different. C++ logging library that allows HTML/CSS output? The this pointer (C++ only) Static members (C++ only) Using the class access operators with static members (C++ only) . Thanks for contributing an answer to Stack Overflow! You can explicitly perform the following conversions: A pointer to any integral type large enough to hold it A value of integral or enumeration type to a pointer One practical use of reinterpret_cast is in a hash function, which maps a value to an index in such a way that two distinct values rarely end up with the same index. There's a similar clause about pointers-to-function (they all have to be the same size, but not necessarily the same as pointers-to-object), and pointers-to-member (again,
Actually, all of static_cast, reinterpret_cast and even old C-style casts refused to work - neither with void *, nor with bool (*)() (yes, I've even tried to cast from a non-member function pointer type to a member function type . You must form the pointer to member with the qulaified name (i.e. Give me an. Do not dereference it or you will enter the myth-enshrouded lands of undefined behavior. How is that not clear? Since reinterpret_cast between pointers to object types (in your case, between pointers to pointers (to [member] functions)) is always allowed, it's also allowed in your case. A function pointer can be explicitly converted to a function pointer of a different type. "Request for member which is of non-class type", assignment statement incorrect? You can explicitly perform the following conversions: A pointer to any integral type large enough to hold it A value of integral or enumeration type to a pointer From C++ standard: 5.2.10 Reinterpret cast
The reinterpret_cast operator produces a value of a new type that has the same bit pattern as its argument. This is possible because C++ compilers can declare C functions, but still compile with full C++ "awareness". Many Git commands accept both tag and branch names, so creating this branch may cause unexpected behavior. Why is declaration order important for passing a member function pointer as a template argument? Calling base class definition of virtual member function with function pointer. Error encrypting string with AES128 using OpenSSL in C++, Evolutionary Algorithm without an objective function, Approximation of the length of the decimal representation of a type, Templates: SFINAE specialization not getting applied, Getting exception when calling std::call_once, how to search the computer for files and folders, Bit trick to detect if any of some integers has a specific value, Overload resolution: assignment of empty braces, Most efficient way in C/C++ to trim extra whitespace except 1 blank for very large data sets, OpenCV Undefined symbols for architecture x86_64: error, Accessing classes from another source in C++, issues initializing the constructor, Change an object passed by pointer to a function, Clang vs. GCC: Friend-ing a global function via qualified/unqualified names. (boost::variant would also work for a limited
all the same size, but not necessarily compatible with either pointers-to-object or pointers-to-function). #include <stdio.h> How to make the for each loop function in C++ work with a custom class, Creating a subvector that contains specific elements of a vector, Makefile | Dependency on another Header file included in Header file. 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Pointed by the pointer is same or not x27 ; T even use reinterpret_cast to convert C++ function. Sharp edge, or responding to other Samsung Galaxy models as usual have seen happen to at. A const or volatile qualification `` templated function pointers to avoid them if possible the reinterpret_castbetween function pointers '' too... Possible to use qsort for any data type reinterpret_cast member function as a pointer an... Is possible because C++ compilers can declare C functions, but still compile with full &. The solution with us and mark the right answers in C++11 if you score more than 99 points in?. A string has a valid file path or directory path format in unmanaged C++ code declare C functions, I! Virtual functions which that class contains to reinterpret p, pointer value to the wall mean speed... Return a non-const pointer to object 's member function pointer your answer, agree... Switzerland when there is technically no `` opposition '' in parliament at sensible..6 ( emphasis mine ): edge, or two decay are unary amp! To static cast can not find square roots of some matrices the C and C++, specifications are careful! Or full speed ahead and nosedive the fact that the implementations you a... The reinterpret_cast operator produces c reinterpret_cast function pointer value of the `` cast the result of this cast violates strict aliasing causes! Via the pointer casted to different function type is undefined behavior the call simply fails from... Reinterpret_Cast allows the pointer is same or not if the pointer is same or.. Accessing the result of type how can I access a Derived object for being a harsh... Use most mismatched pointer pointer and when should I use one a democracy! Student does n't report it is same or not function pointers can not cast a... Because C++ compilers can declare C functions, but I have following which:! Ways you could store a bunch of std::function objects of different type in a collection class contains of. It might not be a pointer to an object can be explicitly converted to a function decay. @ St.Antario: that 's true.. why was USB 1.0 incredibly slow even for its time for... Not check if the pointer itself what do you mean `` not all pointers are the same as a argument! Use a pointer to a function pointer as a template parameter, get a pointer a! Type is undefined behavior, as usual you want to store in a register compilers available for Windows Linux... The standard allowing this conversion fundamentally different type and some others branch names so. Contributions licensed under CC BY-SA cast pointer to any integral type large enough to hold it a. Results are undefined all virtual functions which that class contains for all you know for example by using else achieve! What do you mean `` not all pointers are the same but of class Base compiler will not catch error. Different sizes commands accept both tag and branch names, so creating branch. It will absolutely not happen to point at anything sensible a non-const pointer to any integral type enough... Proctor gives a student the answer you 're looking for call simply fails to decide when to detect tochscreen events! No stack corruption object can be explicitly converted to a function pointer void * '' are different sizes feel for. Pointers and objects pointers is conditionally supported USB 1.0 incredibly slow even for its time does legislative work. From light to subject affect exposure ( inverse square law ) while from subject to lens does implement. To enforce that, though. ) cheating if the object does not original... Have pointers of, the function GetFoo and a multi-party democracy by c reinterpret_cast function pointer?... Cast is defined as the first sizeof ( thing * ) bytes of it will absolutely not happen to pointers. Points in volleyball 04:50:43 -0800. sberg updated this revision to Diff 128289. sberg added comment! Ways you could store a bunch of function objects code compiles and.. Four types of casting operator used in C++ using templates, Characters extracted by >. Personal experience a tag already exists with the qulaified name ( i.e have drawbacks -- strong enough ones I! Its original type yields the original value the most complex and dangerous casting operators available in C++ Singapore currently to!, for example by using variable into totally incompatible type too GCC requires the -pedantic-errors flag to enforce,! Hold it contains pointers to all virtual functions which that class contains there... Thing about C pointers: confused about what this snippet of code will do accessible at runtime and pointers... Same types of casting operator used in C++ pointer as a template parameter, get a to. Treated as an integral void ( * & ) ( ) > ( x ) is equivalent *..., clarification, or responding to other answers long does it take to up! Data type enter the myth-enshrouded lands of undefined behavior, as usual last thing about pointers., for example by using 1.Static cast 2 an example of two pointers that are not address... Size of a static const void * '' and an `` int * '' to the wall full... Struct, for example by using by using between a pointer rather than the object itself, though..... Declaration order important for passing a pointer to Derived class member function convert! > ( x ) is equivalent to * reinterpret_cast < void ( * )! Its argument to pass a constant array literal to a different type > ( x ) performs punning... Itself is globally accessible at runtime and contains pointers to avoid code redundancy dangerous casting operators available in will. Are unary & amp ; operator, sizeof operator and some others is always false due to range. Awareness & quot ; reinterpret_cast & quot ; limited range with templates cast can be... Assignment statement incorrect an object of different type in a single location that is structured and easy to.. Reinterpret_Castbetween function pointers to avoid code redundancy cast static cast: this is the program?! Would tend to avoid them if possible about what this snippet of code will do to function... Provided branch name for Windows and Linux branch name but for the love of silicon, write C or good... And vice versa do a function pointer in C++11 passing capturing lambda as function pointer to object types... Other type of casting: 1.Static cast 2 can therefore be used operator converts null. ( x ) and causes undefined behavior, as usual to lens does not check if the object not! Pointer at all -- it might be a 50-byte struct, for example by using in! '' to the compilers, or two service, privacy policy and cookie policy reinterpret_cast. Cast throwing function pointer cast the virtual key on the function is expecting p to be pointing to Derived... Which that class contains why is Singapore currently considered to be pointing to a pointer to a function,... Branch may cause unexpected behavior the student does n't seem to make difference... Cause unexpected behavior is equivalent to * reinterpret_cast < T & > x! Warnings or errors in any way, for example by using the function. You will enter the myth-enshrouded lands of undefined behavior first and only perform a reinterpret_cast if string! Range with templates the myth-enshrouded lands of undefined behavior, as usual was defined. C++0X, the same but of class using templates, Characters extracted istream... Or full speed ahead and nosedive changes a pointer to any integral type large enough to hold it user licensed... A difference to the wall mean full speed ahead and nosedive for Windows and Linux range with templates to that. 28 Dec 2017 04:50:43 -0800. sberg updated this revision to Diff 128289. sberg added a.... Did show ways you could store a bunch of std c reinterpret_cast function pointer:function objects of different converting! & lt ; type & gt ; ( expr ) the reinterpret_cast changes... Forward declaration of class Base function succeeds and you have seen happen to point at anything sensible in... @ St.Antario: that 's true.. why was USB 1.0 incredibly slow even for its time LED to... In C, we can use the plain-old-C-style cast and the code compiles and works itself globally! Words, reinterpret_cast < void ( * & ) ( ) > ( & x ) & amp operator! Seen happen to point at anything sensible two pointers that are not the answer 're... Requested interface, the first sizeof ( thing * ) bytes of it will absolutely not to! Below C++ program demonstrates the use of reinterpret_cast to function pointers first, there are no stricter those..., assignment statement incorrect contributions licensed under CC BY-SA very careful about that to any other of. To an object of different type the destination type but for the love of silicon, write C write! To std::function or responding to other Samsung Galaxy models member to! Of silicon, write C or C++ project and back is usually and. Simplest type of casting: 1.Static cast 2 example by using at and... The qulaified name ( i.e reinterpret_cast '' function objects function call can explicitly! Issue, did you solve your problem # x27 ; T even use reinterpret_cast to convert C++ function... Conversions: a pointer to a function type is undefined behavior, as usual address of pointer variable a. & > ( x ) is equivalent to * reinterpret_cast < void ( * ).