Compilation Error LNK2019

[Afandi]

I got this compilation error.

When I try to debug, I got these errors.

Error.jpg

main.obj:-1: error: LNK2019: unresolved external symbol "public: void __thiscall Keyboard::setWidget(class QWidget *)" (?setWidget@Keyboard@@QAEXPAVQWidget@@@Z) referenced in function _main

main.obj:-1: error: LNK2019: unresolved external symbol "public: __thiscall Keyboard::Keyboard(class QObject *)" (??0Keyboard@@QAE@PAVQObject@@@Z) referenced in function _main

And the source come from this code.

Keyboard::Keyboard(QObject *parent) : QObject(parent)
{
    theWidget = NULL;
}
 
void Keyboard::setWidget(QWidget* theWidget)
{
    this->theWidget = theWidget;
}

Keyboard::Keyboard(QObject *parent) : QObject(parent)
{
    theWidget = NULL;
}

void Keyboard::setWidget(QWidget* theWidget)
{
    this->theWidget = theWidget;
}

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I hope someone can tell me whether I got missing any things
or I need to change some things in the Build Setting.
Thank you

[ChrisW67]

Assuming that the Keyboard class is in a library, and the errors arise from trying to use it from outside the library, you need to ensure the library can be found in with entries in LIBS (see Declaring Other Libraries) and export the symbols (see Using Symbols from Shared Libraries)

[amleto]

thats a linker error, not a compiler error.

[roumor]

hey i had the same problem. The code was compiling in Qt rc2 and threw unresolved externals when Qt 5 got released.
In RC2 I had set up compiler kit that was pointing towards my vs2010 because the default one didn't work. When Qt 5.0 got released my kit stopped working and the default one became functional instead. I don't know why because their settings were identical.

So if you did same try adding the default kit in your project settings. (button Projects on the left side of Creator and the AddKit button)