{"id":2323,"date":"2012-07-12T18:13:00","date_gmt":"2012-07-12T18:13:00","guid":{"rendered":"https:\/\/blogs.msdn.microsoft.com\/vcblog\/2012\/07\/12\/debugger-type-visualizers-for-c-in-visual-studio-2012\/"},"modified":"2021-10-01T16:06:17","modified_gmt":"2021-10-01T16:06:17","slug":"debugger-type-visualizers-for-c-in-visual-studio-2012","status":"publish","type":"post","link":"https:\/\/devblogs.microsoft.com\/cppblog\/debugger-type-visualizers-for-c-in-visual-studio-2012\/","title":{"rendered":"Debugger Type Visualizers for C++ in Visual Studio 2012"},"content":{"rendered":"

 In Visual Studio 2012, one of the new features for C++ developers is the new native type visualization framework (natvis) added to the debugger which allows customizing the way data types are displayed in debugger variable windows (e. g. autos, watch, locals, and data tips). For those who are familiar with the autoexp.dat<\/b> file that has been used in earlier versions of Visual Studio, this new visualization framework supersedes that and offers xml syntax, better diagnostics, versioning and multiple file support. <\/span><\/p>\n

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To illustrate how type visualizers help make it easier to inspect objects, the following screenshot shows how a std::vector<int> is displayed in the debugger without<\/i> any type visualizers:<\/span><\/p>\n

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\"Image<\/a><\/p>\n

                   <\/span><\/p>\n

The view without type visualizers is not user-friendly and hard to read. You cannot easily see the size or the elements of the vector. Visual Studio ships with type visualizers for common data types such as std::vector and the default view for a std::vector using type visualizers is much more useful:<\/span><\/p>\n

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 <\/h3>\n

Creating a type visualizer for a custom data type<\/span><\/h3>\n

If you have a custom data type you can easily override Visual Studio’s default view of it using this framework and make it easy to inspect objects of that type. To demonstrate how you can do this, let’s go through the process of creating one for the simple rectangle type shown in the code snippet below (the dummy code that uses it is also included):<\/span><\/p>\n

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struct<\/span><\/span><\/span> <\/span>Rectangle<\/span><\/span><\/p>\n

{<\/span><\/p>\n

    <\/span><\/span>int<\/span><\/span> height;<\/span><\/p>\n

    <\/span><\/span>int<\/span><\/span> width;<\/span><\/p>\n

};<\/span><\/p>\n

 <\/span><\/p>\n

int<\/span><\/span><\/span> <\/span>_tmain<\/span><\/span>(<\/span>int<\/span><\/span> <\/span>argc<\/span><\/span>, <\/span>_TCHAR<\/span>* <\/span>argv<\/span><\/span>[])<\/span><\/p>\n

{<\/span><\/p>\n

    <\/span><\/span>Rectangle<\/span> myRectangle<\/span> = { 3<\/span>, 4 };<\/span><\/p>\n

    <\/span><\/span>Rectangle<\/span> myRectangle2 = { 4<\/span>, 4 };<\/span><\/p>\n

 <\/span>   <\/span><\/span>return<\/span><\/span> 0;<\/span><\/p>\n

}<\/span><\/p>\n

 <\/span><\/p>\n

The debugger’s default view of the “myRectangle<\/span>” variable which we are going to customize is as follows:<\/p>\n

 <\/p>\n

\"\"<\/a>  <\/span><\/p>\n

Type visualizers for C++ types are specified in .natvis files. A natvis file is simply an xml file (with .natvis extension) that contains visualization rules for one or more types. At the start of each debugging session, Visual Studio processes any natvis files it can find in the following locations:<\/span><\/p>\n