From the blog

What Is A Forced (Default) Copy Assignment Operator In Modern C++

In the C++ programming language, Object-Oriented Programming (OOP) is a good way to represent data and organize the functionality of your code into logical groups. Classes and Objects are the best way to work on properties and methods. One of the features of OOP IDE is copy assignment operator that is used with “operator=” to create a new object from an existing one. In this post, we explain the use of a forced default copy assignment operator with C++ examples. What are classes and objects in C++? Classes are defined in C++ using keyword class followed by the name of the class. Classes are the blueprint for the objects, and they are user-defined data types that we can use in our program, and they work as an object constructor. Objects are an instantiation of a class. In C++ programming, most of the commands are associated with classes and objects, along with their attributes and methods. Here is a simple class example below.   class Tmyclass {           public:       std::string str; };   then we can create our objects with this Type of myclass as below, What is a copy assignment operator in C++? The Copy Assignment Operator in a class is a non-template non-static member function that is declared with the “operator=“. When you create a class or a type that is copy assignable (that you can copy with the = operator symbol), it must have a public copy assignment operator. Here is a simple syntax for the forced (defaulted) copy assignment operator with default option; Syntax (Since C++11),   class_name & class_name :: operator= ( const class_name& ) = default;   here is an example in a class:   Tmyclass& operator=( const Tmyclass& other) = default; // Copy Assignment Operator   What is a forced (default) copy assignment operator in C++? The forced copy assignment operator forces a copy assignment operator to be generated by the compiler and it is default in any class declarations. This means you don’t need to declare it as above, let’s give examples without using it. Let’s give a simple C++ example to copy assignment operator with default option, here is a simple class   class Tmyclass {   public:   std::string str;   };   This is same as below.   class Tmyclass {   public:   std::string str;     Tmyclass& operator=( const Tmyclass& other) = default; // Forced (Default) Copy Assignment Operator   };   As you see both are same, because this is default in any class declaration and it is automatically declared. And here is how you can use this “=” copy assignment operator on the objects of one of these given class examples,   Tmyclass o1, o2;   o2 = o1; // Using Copy Assingment Operator   Is there a full example to forced (default) copy assignment operator in C++? An example with a copy assignment operator in a class. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28   #include #include   class Tmyclass {   public:   std::string str;     // Tmyclass& operator=( const Tmyclass& other) = default; // Forced (Default) Copy Assignment Operator   };   int main() { Tmyclass o1, o2;   o1.str = “LearnCplusplus.org”;   o2 = o1; // Using Copy Assingment Operator   std::cout

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MSVC ARM64 optimizations in Visual Studio 2022 17.6 

In the last couple of months, the Microsoft C++ team has been working on improving MSVC ARM64 backend performance and we are excited to have a couple of optimizations available in the Visual Studio 2022 version 17.6. These optimizations improved code-generation for both scalar ISA and SIMD ISA (NEON). Let’s review some interesting optimizations in this blog.  Before diving into technical details, we’d encourage you to create feedback here at Developer Community if you have found performance issues. The feedback helps us prioritize work items in our backlog. This, optimize neon right shift into cmp, is an example of good feedback. Including a tagged subject title, detailed description of the issue, and a simple repro simplifies our analysis work and helps us deliver a fix more quickly.  Now, let’s see the optimizations.  Auto-Vectorizer supports more NEON instructions with asymmetric operands The ARM64 backend already supports some NEON instructions with asymmetric typed operands, like Add/Subtract Long operations (SADDL/UADDL/SSUBL/USUBL). These instructions add each vector element in the lower or upper half of the first source SIMD register to the corresponding vector element of the second source SIMD register and write the vector result to the destination SIMD register. The destination vector elements are twice as long as the source vector elements. Now, we have extended such support to Multiply-Add Long and Multiply-Subtract Long (SMLAL/UMLAL/SMLSL/UMLSL).  For example:  void smlal(int * __restrict dst, int * __restrict a,             short * __restrict b, short * __restrict c)  {  for (int i = 0; i < 4; i++)  dst[i] = a[i] + b[i] * c[i];  } In Visual Studio 2022 17.5, the code-generation was:  sxtl        v19.4s,v16.4h  sxtl        v18.4s,v17.4h  mla         v20.4s,v18.4s,v19.4s    Extra signed extensions are performed on both source operands to match the type of destination. Now it has been optimized into a single smlal v16.4s,v17.4h,v18.4h.  The ARM64 ISA further supports another variant for these operations, which is called Add/Subtract Wide. For them, the asymmetry happens between source operands, not between source and destination.  For example:  void saddw(int *__restrict dst, int *__restrict a, short *__restrict b)  {  for (int i = 0; i < 4; i++)  dst[i] = a[i] + b[i];  } In Visual Studio 2022 17.5, the code-generation was:  sxtl        v17.4s,v16.4h  add         v18.4s,v17.4s,v18.4s   The narrow source gets extra signed extension to match the other wide source. In the 17.6 release, this has been optimized into a single saddw v16.4s,v16.4s,v17.4h. The same applies to UADDW/SSUBW/USUBW.  Auto-vectorizer now supports small types on ABS/MIN/MAX  ABS/MIN/MAX have slightly complex semantics. Normally, the compiler middle-end or back-end will have a pattern matcher to recognize IR sequences with if-then-else semantics and see if they could be converted into ABS/MIN/MAX. There is an issue when the operands are in small types (int8 or int16) though.   As specified by the C++ standard, small types are promoted to int, which is 32-bit on ARM64. This is perfect for scalar operations because they really can only operate on scalar register width. For ARM64, the smallest width is 32-bit utilizing the sub-register. However, this is not true for SIMD ISA whose minimum operation width is the width of vector lane (element). For example, ARM64 NEON supports operating on int8, int16 for a couple of operations including ABS/MIN/MAX. So, to generate SIMD instructions operating on small element sizes and deliver higher computing throughput, the auto-vectorizer needs to do […]

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What is Avoiding Implicit Copy Assignment In C++?

Object-Oriented Programming (OOP) is a method of mapping real-world objects and data to computer functions and data structures. Classes and Objects are part of object-oriented methods and typically provide features such as properties and methods. In Modern C++, one of the features of OOP is copy assignment operator that is used with “operator=” to create a new object from an existing one. In this post, we explain what we mean by “avoiding implicit copy assignment operator”, and how can we use the delete option with copy assignment in C++ examples. What are classes and objects in C++? Classes are defined in C++ using the keyword class followed by the name of the class. Classes are the blueprint for the objects and they are user-defined data types that we can use in our program. Objects are an instantiation of a class, In C++ programming, because it is designed to be strongly object oriented most of the commands are associated with classes and objects, along with their attributes and methods. Here is a simple class example below.   class Tmyclass {           public:       std::string str; };   Then we can create our objects with this Type of myclass as below. What is copy assignment operator with delete option in C++? The Copy Assignment Operator in a class is a non-template non-static member function that is declared with the “operator=“. Normally, a copy assignment operator is assigned in any class deceleration as default. For example, we can copy two object properties as below;   class Tmyclass {           public:       std::string str; };   Tmyclass o1, o2;   o1.str = “LearnCPlusPlus.org”;   o2 = o1;   When you create a class or a type that is copy assignable (that you can copy with the = operator symbol), sometime you don’t want it to be copied with other external code lines. In this situation, you need to use copy assignment operator with delete option. Here is a simple syntax for the copy assignment operator with delete option; Syntax (Since C++11),   class_name & class_name :: operator= ( const class_name& ) = delete;   Here is an example in a class:   Tmyclass& operator=( const Tmyclass& other) = delete; // Deleting Copy Assignment Operator   What is avoiding implicit copy assignment in C++? In C++, the Copy Assignment operator is default in any class declaration and it is automatically declared. This is also called as the forced copy assignment operator which is default in any class declarations. This means, if you don’t want this default feature, you should delete by using delete option as given syntax above. Let’s give a simple C++ example of the copy assignment operator with default option, here is a simple class:   class Tmyclass {   public:   std::string str; };   In modern C++, this simple class has hidden copy assignment operator as default that is created automatically, this class example is same as below:   class Tmyclass {   public:   std::string str;     Tmyclass& operator=( const Tmyclass& other) = default; // Copy Assignment Operator   };   As you see both are same, and if you want to delete this copy operator to avoid implicit copy assignment usage, you need to use delete option as below.   class Tmyclass {   public:   std::string str;     Tmyclass& operator=( const Tmyclass& other) = delete; // Deleted Copy Assignment Operator   };   And here […]

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Pure Virtual C++ 2023 Pre-Conference Videos

Pure Virtual C++ is our free, annual, one-day virtual conference for the whole C++ community. This year it is running June 6th and you can find the session list and sign-up for free on the event page. In the run up to the conference we will be publishing new C++ videos every day. You can find the playlist on YouTube. The first two videos on Breakpoint Groups and Improved Step Filtering in the Visual Studio Debugger are live now!

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What Is A Copy Assignment Operator in C++?

Object-Oriented Programming (OOP) is a method of mapping real-world objects and data to computer functions and data structures. Classes and Objects are part of object-oriented methods and typically provide features such as properties and methods. One of the features of an OOP Editor is a copy assignment operator that is used with “operator=” to create a new object from an existing one. In this post, we explain what a copy assignment operator is along with some C++ examples. What are classes and objects in C++? Classes are defined in C++ using the keyword class followed by the name of the class. Classes are the blueprint for the objects and they are user-defined data types that we can use in our program. Objects are an instantiation of a class, In C++ programming, because it is designed to be strongly object oriented most of the commands are associated with classes and objects, along with their attributes and methods. Here is a simple class example below.   class myclass {           public:       std::string str; };   What is a copy assignment operator in C++? The Copy Assignment Operator in a class is a non-template non-static member function that is declared with the “operator=“. When you create a class or a type that is copy assignable (that you can copy with the = operator symbol), it must have a public copy assignment operator. Here is a simple syntax for the typical declaration of a copy assignment operator which is defaulted, Syntax (Since C++11).   class_name & class_name :: operator= ( const class_name& ) = default;   Here is an example in a class.   Tmyclass& operator=(const Tmyclass& other) = default; // Copy Assignment Operator   Is there a simple example of using the copy assignment operator in C++? The forced copy assignment operator is default in any class declarations. This means you don’t need to declare it as above, let’s give examples without using it. Let’s give a simple C++ example to copy assignment operator with default option, here is a simple class.   class myclass {   public:   std::string str;   };   Because this is default in any class declaration, and it is automatically declared. This class is same as below.   class myclass {   public:   std::string str;     Tmyclass& operator=(const Tmyclass& other) = default; // Copy Assignment Operator };   And here is how you can use this “=” copy assignment operator with both class examples above.   Tmyclass o1, o2;   o2 = o1; // Copy Assingment Operator   Is there a full example of how to use the copy assignment operator in C++? An example with a copy assignment operator in a Class. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27   #include #include   class Tmyclass {   public:   std::string str;        // Tmyclass& operator=(const Tmyclass& other) = default; // Copy Assignment Operator };   int main() { Tmyclass o1, o2;   o1.str = “LearnCplusplus.org”;   o2 = o1; // Using Copy Assingment Operator   std::cout

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Typical Declaration Of A Copy Assignment Operator With std::swap

Object-Oriented Programming (OOP) is a method of mapping real-world objects and data to computer functions and data structures. Classes and Objects are part of object-oriented methods and typically provide features such as properties and methods. One of the features of an OOP tool is the copy assignment operator that is used with “operator=” to create a new object from an existing one. In this post, we explain the typical declaration of a copy assignment operator with C++ examples. What are classes and objects in C++? Classes are defined in C++ using the keyword class followed by the name of the class. Classes are the blueprint for the objects and they are user-defined data types that we can use in our program. Objects are an instantiation of a class, In C++ programming, because it is designed to be strongly object oriented most of the commands are associated with classes and objects, along with their attributes and methods. Here is a simple class example below.   class myclass {           public:       std::string str; };   What is a copy assignment operator in C++? The Copy Assignment Operator in a class is a non-template non-static member function that is declared with the “operator=“. When you create a class or a type that is copy assignable (that you can copy with the = operator symbol), it must have a public copy assignment operator. Here is a simple syntax for the typical declaration of a copy assignment operator when the swap is used. Syntax:   class_name & class_name :: operator= ( class_name )   Here is an example in a class.   class Tmyclass {   public:   Tmyclass& operator=(Tmyclass other) // Using Copy Assingment Operator   {    // Copy or swap things    return *this;   } };   What is a typical declaration of a copy assignment operator with std::swap? Let’s give a simple C++ example of a typical declaration of a copy assignment operator with std::swap.   class myclass {   public:   std::string str;     myclass& operator=(myclass other)   {        std::cout

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Typical Declaration Of A Copy Assignment Operator Without std::swap

Object-Oriented Programming (OOP) is a method of mapping real-world objects and data to computer functions and data structures. Classes and Objects are part of object-oriented methods and typically provide features such as properties and methods. One of the features of an OOP IDE is the copy assignment operator that is used with “operator=” to create a new object from an existing one. In this post, we explain what the typical declaration of copy assignment operator is along with some C++ examples. What are classes and objects in C++? Classes are defined in C++ using the keyword class followed by the name of the class. Classes are the blueprint for the objects and they are user-defined data types that we can use in our program. Objects are an instantiation of a class, In C++ programming, because it is designed to be strongly object oriented most of the commands are associated with classes and objects, along with their attributes and methods. Here is a simple class example below.   class myclass {           public:       std::string str; };   What is copy assignment operator in C++? The Copy Assignment Operator in a class is a non-template non-static member function that is declared with the “operator=“. When you create a class or a type that is copy assignable (that you can copy with the = operator symbol), it must have a public copy assignment operator. Here is a simple syntax for the typical declaration of a copy assignment operator when the copy and swap idiom is not used, Syntax.   class_name & class_name :: operator= ( const class_name& )   Here is an example in a class.   Tmyclass& operator=( const Tmyclass& other) // Using Copy Assingment Operator { if (this != &other) // not a self-assignment { // Copy or swap things }    return *this; }   What is typical declaration of a copy assignment operator without std::swap? Let’s give a simple C++ example of the typical declaration of a copy assignment operator with std::swap. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17   class Tmyclass {   public:   std::string str;     Tmyclass& operator=( const Tmyclass& other) // Using Copy Assingment Operator   { if (this != &other) // not a self-assignment { std::cout

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5 New Posts With Free C++ Builder CE, Dev-C++, BCC, GCC Examples

Hello developers, if you just starting out on your C++ journey and want to jump to a modern IDE and C++ compiler, there is a free version of C++ Builder, C++ Builder 11 CE Community Edition released on April 2023. If you are a start-up developer, student, hobbyist, or just interested in learning to code then the C++ Builder Community Edition may well be just the thing for you. Read the FAQ notes on the CE license and then simply fill out the form to download C++ Builder 11 CE. Today we have 5 more C++ posts, some of C++ examples in these posts can be used with C++ Builder or the C++ Builder 11 CE Community Edition, and others can be used with Dev-C++, BCC C++ Compilers, and some other compilers such as the GCC compiler. Table of Contents Where can I learn to program with free C++ examples? What is new in C++ Builder CE? What are the important features of C++ that can be used with C++ Builder CE? Learn C++ Builder CE with C++ examples Get in touch and tell us what you’d like to see on the blogs What might be next for C++ Builder? Where can I learn to program with free C++ examples? If you don’t know anything about C++ or the C++ Builder IDE, don’t worry, we have a lot of great examples on LearnCPlusPlus.org website and they’re all completely free. Just visit this site and copy and paste any examples there into a new Console, VCL, or FMX project, depending on the post example. We keep adding more C and C++ posts with sample code. In today’s round-up of recent posts on LearnCPlusPlus.org, we have new C and C++ posts with very simple examples that can be used with: The free version of C++ Builder 11 CE Community Edition or a professional C++ Builder  or free BCC32C C++ Compiler and BCC32X C++ Compiler or the free Dev-C++ What is new in C++ Builder CE? C++ Builder 11 CE which is the free Edition of C++ Builder has been recently released. Embarcadero has made available a Community Edition license for the most recent 11.3 release of Delphi and C++Builder. This is a free edition of either Delphi or C++Builder for students, hobbyists, and startups (as the license is revenue-limited). What are the important features of C++ that can be used with C++ Builder CE? C++ is one of the most powerful programming languages that we use for all sorts of purposes, from regular applications, games, business, industrial infrastructure, robotics, and in the control of IoT devices. The most well-known controllers for those areas where human and computer interaction are important and stretches beyond simple keyboard input are joysticks or gamepads. One of the simplest examples to use them on Windows is using the venerable XInput library which has been around for quite a long time but can still be easily used with the latest C++ Compiler. In the first post, we explain how you can use a gamepad or joystick controller in C++ with the Xinput library. https://learncplusplus.org/how-to-use-a-game-pad-or-joystick-controller-in-c-on-windows/ C++ Builder is the easiest and fastest C++ IDE for building professional applications with powerful GUI components like Memo, Edit, ListBox, StringGrid and many more. Each component can be skinned with Styles to change their visual appearance. Styles are very powerful and because of this it can […]

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CIOs are investing more in digital workflows — and reaping the rewards

The way businesses support employees has changed dramatically in the last few years — and chief information officers (CIOs) are tasked with keeping up. With employees sent home to work remotely in 2020, businesses had no choice but to shift from paper to digital workflows to get work done. But there’s still more work to do if businesses want to realize the benefits that come with digital processes. By investing in greater digitization, CIOs can help their organizations make the most of data analytics and insights, unlock new business and revenue opportunities, and significantly reduce costs. Nearly half (49 percent) of CIOs surveyed said time and operational constraints had led to incomplete or unsatisfactory restructurings, with two-thirds saying they plan to develop their digital document processes further. Here’s why CIOs are so intent on continuing their investment in digital workflows. Increased productivity Currently, less than half of CIOs say their digital workflows aka document processes are either advanced or leading. This stage is defined as document digitization that is available to everyone and artificial intelligence (AI) that supports orchestration and decision-making based on data. The impact of not having advanced digital workflows is often less efficiency and productivity within the organization. About half of the CIOs surveyed (51 percent) admitted that legacy workflows were impeding productivity in their organizations. In the report, 451 Research’s Conner Forrest noted, “As we continue to invest in modern technology, especially through things like automation and artificial intelligence — whether it’s in document workflows or elsewhere — we are making an investment in freeing employees up to work more strategically, to think more creatively.” This is an important point. As CIOs, our role isn’t just to decide what technology is best, but to implement technology that frees up employees to work as productively and strategically as possible. Improved employee and customer experiences When workflows and internal processes are fully digitized, the CIOs surveyed by Forbes say the two most likely outcomes are more efficient employees (65 percent) and higher morale (63 percent). In the report, Forrest is quoted as saying, “The more we invest in the tools and technologies we use to get our work done, the better engaged our employees are.” Likewise, Microsoft chief digital officer Andrew Wilson also noted in the report that digitization can have a significant impact on the customer experience. “If employees aren’t spending time scanning and uploading documents or chasing down contracts, they have time for higher-value work — and that work can often directly impact the customer.” Better business outcomes Perhaps the most critical reason to invest in digital workflows is the overall impact on business outcomes. Organizations understand there are many benefits related to optimized workflows that may not seem all that obvious. Nearly four in ten (39 percent) CIOs said the top benefit they expected to see from improving workflow is a better ability to leverage data analytics and insights. The second most-cited benefit (38 percent) was new business or revenue opportunities. Improving workflows is a strategic investment. Immediate ROI and cost savings can depend on a range of factors including executive and manager buy-in, implementation, ongoing service and iteration, and employee usage. While you may not see immediate cost savings at the flip of a switch, better digital processes can set your business up for […]

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What Is The Rule of Zero in C++?

Object Oriented Programming (OOP) is a way to integrate with objects which can contain data in the form (attributes or properties of objects), and code blocks in the form of procedures (methods, functions of objects). These attributes and methods are variables and functions that belong to the class – part of the class’s code and they are generally referred to as class members. Classes and structs are very useful in modern programming. There are some rules to support the principles of programming, one of which is the Rule of Zero in C++. In this post, we explain what is Rule of Zero in C++ with examples. What is resource acquisition in C++? The principle of Resource Acquisition Is Initialization (RAII) term used in several OOP programming languages, which relates to the ability to manage resources, such as memory, through the copy and move constructors, destruction, and assignment operators. RAII is about the declaration and use of destructors, copy-move operators, and memory management in these members and methods. These cause new rules in development. What is the Single Responsibility Principle in C++? The Single Responsibility Principle (SRP) is a computer programming principle that states “A module should be responsible to one, and only one, actor.” This principle exposes a rule for the classes in C++, called Rule of Zero. Now, let’s see what the Rule of Zero in C++ is. What is the Rule of Zero in C++? Rule of Zero means that, if all members have default member functions, no further work is needed. This is the simplest and cleanest semantics of programming. The compiler provides default implementations for all of the default member functions if there are no special member functions that are user-defined. In other words, you should prefer the case where no special member functions need to be defined. In this rule, classes that have custom destructors, copy/move constructors, or copy/move assignment operators should deal exclusively with ownership; other classes should not have custom destructors, copy/move constructors or copy/move assignment operators. Rule of Zero helps simplify our C++ code without risking resource management issues at run time. The term The Rule of Zero was coined by R. Martinho Fernandes in his paper in 2012. This paper is highly recommended reading to get the full details of this concept. The Rule of Zero rule can be seen in the C++ Core Guidelines here C.20: If you can avoid defining default operations, do. As in the example below, std::map and std::string have all the special functions, so you don’t need to create a constructor and destructor for them.   class Tmy_map {     public:       // … no default operations       private:       std::string title;       std::map<int, int> coords; };   Tmy_map m;       // default construct Tmy_map m2 {m};  // copy construct   How can we apply the Rule of Zero in C++? Here are some notes as to-dos in Rule of Zero. A simple empty C++ class is perfectly equivalent to default implementations (Rule of Five) in a class. A modern compiler is able to provide a default implementation, in example, this simple class. This class is exactly the same as the one below in modern C++.   class Tx { public:    Tx() = default;       Tx(Tx const& other) = default;    Tx& operator=(Tx const& other) = default;       Tx(Tx&& other) = default;    Tx& operator=(Tx&& other) = default;       ~Tx() = default; }   Use a std::unique_ptr if your class can be moved but should not […]

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