Debugging
To help with debugging there are debugger visualizers or debugging helpers allowing to display a variable in a manner appropriate to its data type. For Visual Studio there is also an extension displaying graphical representations of geometries during debugging.
For Visual Studio 2013, 2015, 2017 debugger visualizers are installed together with the Graphical Debugging extension available here
For Visual Studio 2012, 2013, 2015, 2017 you may also manually use *.natvis files from here, in particular this file
For Qt 3 you may use files from here, in particular this file