Error: c2665: "qmessagebox:: critical": none of the four overloads can convert all parameter types

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Preface

In the use of QMessageBox::criticalQtCreator Compiler error ：
E:\QtExercise\QtReadWriteXml\QtXmlDom\QtXmlDom\AnalysisTrackDpj.cpp:39: error: C2665: “QMessageBox::critical”: 4 None of the overloads can convert all parameter types

One 、 Question why

1. The first thing to think about is not including QMessageBox The header file , So include QMessageBox The header file , But the problem is still unsolved

2. Let yourself define AnalysisTrackDpj Class inheritance QMessageBox
Although the compilation has passed , It works ,
But the compiler gives a warning ：direct base ‘QObject’ is inaccessible due to ambiguity：
Think I let AnalysisTrackDpj Inherit separately QObject and QMessageBox, and QMessageBox Inherit again QObject, I always feel that there is a problem

3. take this Change to 0
Through continuous testing and consulting data, it is found that this The problem of pointer . because information The first parameter type of the static function is QWidget* parent. And my DatabaseOperatoor.cpp There is no window to create , hold this Pass to information, The compiler cannot determine who its parent window is . The solution is to this Change to 0, I am the top window , solve the problem .
For detailed description, click c++ - About Qt MessageBox::warning() overloading - Stack Overflow To view the

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