What's New in Visual C++ 2010
This document introduces new and enhanced Visual C++ features in Visual Studio 2010.
The auto keyword has a new purpose. Use the default meaning of the auto keyword to declare a variable whose type is deduced from the initialization expression in the declaration of the variable. The /Zc:auto compiler option invokes either the new or the previous meaning of the auto keyword.
decltype Type Specifier
The decltype type specifier returns the type of a specified expression. Use the decltype type specifier in combination with the auto keyword to declare a type that is either complex or known only to the compiler. For example, use the combination to declare a template function whose return type depends on the types of its template arguments. Or, declare a template function that calls another function, and then returns the return type of the called function.
Use a lambda function by itself, as a template function parameter instead of a function object, or together with the auto keyword to declare a variable whose type is a lambda.
The rvalue reference declarator (&&) declares a reference to an rvalue. An rvalue reference lets you use move semantics and perfect forwarding to write more efficient constructors, functions, and templates.
A static_assert declaration tests a software assertion at compile time, unlike other assertion mechanisms that test at run time. If the assertion fails, the compilation fails and a specified error message is issued.
nullptr and __nullptr Keywords
The Visual C++ compiler lets you use the nullptr keyword with native code or with managed code. The nullptr keyword indicates that an object handle, interior pointer, or native pointer type does not point to an object. The compiler interprets nullptr to be managed code when you use the /clr compiler option, and native code when you do not use the /clr option.
The Microsoft-specific __nullptr keyword has the same meaning as nullptr, but it applies to native code only. If you compile native C/C++ code by using the /clr compiler option, the compiler cannot determine whether the nullptr keyword is a native or a managed term. To make your intention clear to the compiler, use the nullptr keyword to specify the managed term, and __nullptr to specify the native term.
/Zc:trigraphs Compiler Option
By default, support for trigraphs is disabled. Use the /Zc:trigraphs compiler option to enable trigraphs support.
A trigraph consists of two consecutive question marks (??) followed by a unique third character. The compiler replaces a trigraph with the corresponding punctuation character. For example, the compiler replaces the ??= trigraph with the # (number sign) character. Use trigraphs in C source files that use a character set that does not contain certain punctuation characters.
New Profile-Guided Optimization Option
PogoSafeMode is a new profile-guided optimization option that lets you specify whether to use safe mode or fast mode when you optimize your application. Safe mode is thread-safe, but it is slower than fast mode. Fast mode is the default behavior.
New Common Language Runtime (CLR) Option /clr:nostdlib
A new option is added for /clr (Common Language Runtime Compilation). If different versions of the same libraries are included, a compile error is issued. The new option lets you exclude the default CLR libraries so that your program can use a specified version.
New pragma directive detect_mistmatch
The pragma directive detect_mismatch lets you put a tag in your files that is compared to other tags that have the same name. If there are multiple values for the same name, the linker issues an error.
XOP Intrinsics, FMA4 Intrinsics, and LWP Intrinsics
New intrinsic functions have been added to support the XOP Intrinsics Added for Visual Studio 2010 SP1, FMA4 Intrinsics Added for Visual Studio 2010 SP1, and LWP Intrinsics Added for Visual Studio 2010 SP1 processor technologies. Use __cpuid, __cpuidex to determine which processor technologies are supported on a particular computer.
Visual C++ solutions and projects are now built by using MSBuild.exe, which replaces VCBuild.exe. MSBuild is the same flexible, extensible, XML-based build tool that is used by the other Visual Studio languages and project types. Because of this change, Visual C++ project files now use an XML file format and have the .vcxproj file name extension. Visual C++ project files from earlier versions of Visual Studio are automatically converted to the new file format. For more information, see MSBuild (Visual C++).
The VC++ directories setting is now located in two places. Use project property pages to set per-project values for VC++ directories. Use the Property Manager and a property sheet to set global, per-configuration values for VC++ directories.
In earlier releases, defined dependencies between projects were stored in the solution file. When these solutions are converted to the new project file format, dependencies are converted to project-to-project references. This change can affect applications because the concepts of solution dependencies and project-to-project references are different.
Macros and Environment Variables
The new _ITERATOR_DEBUG_LEVEL macro invokes debugging support for iterators. Use this macro instead of the older _SECURE_SCL and _HAS_ITERATOR_DEBUGGING macros.
Concurrency Runtime Libraries
The Concurrency Runtime framework supports applications and components that run simultaneously, and is the framework for programming concurrent applications in Visual C++. To support concurrent-application programming, the Parallel Patterns Library (PPL) provides general-purpose containers and algorithms for performing fine-grained parallelism. The Asynchronous Agents Library provides an actor-based programming model and message passing interfaces for coarse-grained dataflow and pipelining tasks.
Standard C++ Library
The following list describes many of the changes that have been made to the Standard C++ Library.
The new rvalue reference C++ language feature has been used to implement move semantics and perfect forwarding for many functions in the Standard Template Library. Move semantics and perfect forwarding greatly improve the performance of operations that allocate or assign variables or parameters.
Rvalue references are also used to implement the new unique_ptr class, which is a safer smart pointer type than the auto_ptr class. The unique_ptr class is movable but not copyable, implements strict ownership semantics without affecting safety, and works well with containers that are aware of rvalue references. The auto_ptr class is deprecated.
Singly linked lists are supported by the <forward_list> header.
The new cbegin, cend, crbegin, and crend member functions provide a const_iterator that moves forward or backward through a container.
The <system_error> header and related templates support the processing of low-level system errors.
The <codecvt> header supports converting various encodings of Unicode characters to other encodings.
The <allocators> header defines several templates that help allocate and free memory blocks for node-based containers.
There are numerous updates to the <random> header.
Microsoft Foundation Class (MFC) Library
Windows 7 Features
MFC supports many Windows 7 features, for example, the Ribbon user interface (UI), the Taskbar, jump lists, tabbed thumbnails, thumbnail previews, the progress bar, icon overlay, and search indexing. Because MFC automatically supports many Windows 7 features, you may not have to modify your existing application. To support other features in new applications, use the MFC Application Wizard to specify the functionality you want to use.
MFC supports applications that have a multi-touch user interface, for example, applications that are written for the Microsoft Surface operating system. A multi-touch application can handle Windows touch messages and gesture messages, which are combinations of touch messages. Just register your application for touch and gesture events and the operating system will route multi-touch events to your event handlers.
By default, MFC applications are now High-DPI-aware. If an application is High-DPI (high dots per inch) aware, the operating system can scale windows, text, and other UI elements to the current screen resolution. This means that a scaled image is more likely to be correctly laid out, and not clipped or pixelated.
The restart manager automatically saves documents and restarts your application if it unexpectedly closes or restarts. For example, you can use the restart manager to start your application after it is closed by an automatic update. For more information about how to configure your application to use the restart manager, see How to: Add Restart Manager Support.
The new SafeInt Library performs safe arithmetic operations that account for integer overflow. This library also compares different kinds of integers.
New Active Template Library (ATL) macros
New macros have been added to ATL to expand the functionality of PROP_ENTRY_TYPE and PROP_ENTRY_TYPE_EX. PROP_ENTRY_INTERFACE and PROP_ENTRY_INTERFACE_EX let you add a list of valid CLSIDs. PROP_ENTRY_INTERFACE_CALLBACK and PROP_ENTRY_INTERFACE_CALLBACK_EX let you specify a callback function to determine whether a CLSID is valid.
Most /analyze (Enterprise Code Analysis) warnings have been removed from the C Run-Time (CRT), MFC, and ATL libraries.
Animation and D2D support
MFC now supports animation and Direct2D graphics. The MFC library has several new MFC classes and functions to support this functionality. There are also two new walkthroughs to show how to add a D2D object and an animation object to a project. These walkthroughs are Walkthrough: Adding a D2D Object to an MFC Project and Walkthrough: Adding Animation to an MFC Project.
In Visual C++ 2010, the integrated development environment (IDE) has significant improvements in performance, accuracy, scalability, and tools to help you be productive.
IntelliSense for Visual C++ has been completely redesigned to be faster, more accurate, and able to handle larger projects. To achieve this improvement, the IDE makes a distinction between how a developer views and modifies source code, and how the IDE uses source code and project settings to build a solution.
Because of this separation of duties, browsing features such as Class View and the new Navigate To dialog box are handled by a system that is based on a new SQL Server desktop database (.sdf) file that replaces the old no compile browse (.ncb) file. IntelliSense features such as Quick Information, Auto Completion, and Parameter Help parse translation units only when required. Hybrid features such as the new Call Hierarchy window use a combination of the browse and IntelliSense features.
Because IntelliSense processes only the information that you require at the moment, the IDE is more responsive. Also, because information is more up to date, IDE views and windows are more accurate. Finally, because the IDE infrastructure is better organized, more capable, and more scalable, it can handle larger projects.
Improved IntelliSense Errors
The IDE better detects errors that could cause a loss of IntelliSense and displays red wavy underlines under them. In addition, the IDE reports IntelliSense errors to the Error List Window. To display the code that is causing the problem, double-click the error in the Error List Window.
#include Auto-Complete Feature
The IDE supports auto-completion for the #include keyword. When you type #include, the IDE creates a drop-down list box of valid header files. If you continue by typing a file name, the IDE filters the list based on your entry. At any point, you can select from the list the file you want to include. This lets you quickly include files without knowing the exact file name.
The Navigate To dialog box lets you search for all symbols and files in your project that match a specified string. Search results are immediately revised as you type additional characters in your search string. The Results feedback field tells you the number of items found and helps you decide whether to constrain your search. The Kind/Scope, Location, and Preview feedback fields help you disambiguate items that have similar names. In addition, you can extend this feature to support other programming languages.
Parallel Debugging and Profiling
The Visual Studio debugger is aware of the Concurrency Runtime and helps you troubleshoot parallel processing applications. You can use the new concurrency profiler tool to visualize the overall behavior of your application. Also, you can use new tool windows to visualize the state of tasks and their call stacks.
The Ribbon Designer is a graphical editor that lets you create and modify an MFC ribbon UI. The final ribbon UI is represented by an XML-based resource file (.mfcribbon-ms). For existing applications, you can capture your current ribbon UI by temporarily adding a few lines of code and then invoking the Ribbon Designer. After the ribbon resource file is created, you can replace your handwritten ribbon UI code with a few statements that load the ribbon resource.
The Call Hierarchy window lets you navigate to all functions that are called by a particular function, or to all functions that call a particular function.
MFC Class Wizard
Visual C++ 2010 brings back the well-regarded MFC Class Wizard tool. The MFC Class Wizard is a convenient way to add classes, messages, and variables to a project without having to manually modify sets of source files.
ATL Control Wizard
The ATL Control Wizard no longer automatically populates the ProgID field. If an ATL control does not have a ProgID, other tools may not work with it. One example of a tool that requires controls to have a ProgID is the Insert Active Control dialog box. For more information about the dialog box, see Insert ActiveX Control Dialog Box.
The addition of the YMMWORD data type supports the 256-bit multimedia operands that are included in the Intel Advanced Vector Extensions (AVX) instructions.