c++visual-studioqtinclude

Can't include <QtWidgets>

I'm trying to link Qt5 in Visual Studio 15 2017.

I have added the paths and file references for additional (1) include directories, (2) library directories and (3) dependencies in the Property Pages.

I can include header files by refering to their path like this

#include <QtWidgets/qpushbutton.h>

However, the github project I'm trying to build uses this line

#include <QtWidgets>

Visual Studio shows me an error on those lines

E1696   cannot open source file "QtWidgets"

When creating a solution from a .pro file using the Qt VS Tools in Visual Studio, I can include <QtWidgets>. But how can I include it in my existing project, which has not been created from a .pro file.

Solution Placing a MyProjectName.pro file (with QT += core gui widgets) in the MyProjectName Folder and opening it with Qt VS Tools > Open Qt Project File (.pro) solves this problem. I can now include <QtWidgets>. But this doesn't seem like the correct way, given the VS gui.

Solution

  • The "QtWidgets" include file is a file in the "QtWidgets" directory. Your include path probably has something like "$(QTDIR)/include", but not "$(QTDIR)/include/QtWidgets". That's why your example with "QtWidgets/qpushbutton.h" works, but not just "QtWidgets" on its own.

    Maybe it helps to look at the full path to the file you're trying to include (using my Qt 5.5.1 installation):

    C:\Qt\Qt5.5.1\5.5\msvc2013_64\include\QtWidgets\QtWidgets

    So if you have this in your include path:

    C:\Qt\Qt5.5.1\5.5\msvc2013_64\include

    That only gets you to the QtWidgets directory, but not to the QtWidgets file.

    You also needs this in your include path:

    C:\Qt\Qt5.5.1\5.5\msvc2013_64\include\QtWidgets

    Obviously, adjust this for your installed drive, Qt version, and MSVC version.