error: ISO C++ forbids declaration of ‘mainScreenDLG’ with no type

[ChrisW67]

no, Ui::mainScreenDLG must be in ui_menuScreen.h, look for it.

Greenscape, you seem to be confusing me with the author of the broken program.

the object name is "mainScreenDLG" in the file mainScreen.ui (created in Qt Designer)
i think that it hadnt recognised the mainScreen.ui file until i re-opened it in Designer for some reason. that or i had misnamed it and
but im still getting the "13: error: expected class-name before ‘{’ token"

Qmake will generate uic commands for the .ui file "mainScreen.ui" to generate a file "ui_mainScreen.h" that contains the definitions for the objects in the design. Your code defining "class mathsGame" (first post) includes a file called "ui_menuScreen.h", which presumably relates to a different Designer form that does not define mainScreenDLG.

on a related note, the code from my "mainScreen.cpp" file is experiencing errors

Probably because it does not know of an object by the name btnCheck which the error reports as "<unresolved overloaded function type>".

[hippo]

Baxter

u try to change class name:mainScreen to myMainScreen or rename other

mainScreen，MainScreen may be retained by QT Create