How do classes work in Qt?
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Hi! I'm really new to Qt, but i've been picking it up at a decent pace. I've been trying to use a class I added into the header file that was created in the program and make an array, but I couldn't get the class array to work. I tried changing it into a class , and that didn't work either. I did some snooping around in google and the documentation, but was unable to find anything. How does classes, and class arrays, work in Qt?
Class in the header file:
class int_paint { QString ID; //no usage other than programming QString unit; QString substrate; // area that is being painted QChar UOM; // unit of measure int quantity; double lf_conversion; //linear feet conversion int sq_per_gal; //square feet per gal double coats; bool f_or_s; double flat_per_unit; double semi_per_unit; int multiplier; //dependant on number of apartments double subtotal_flat; double subtotal_semi; int waste; double waste_total_flat; //subtotal * waste (waste must be entered as an int representing a %, conv it to decimal) double waste_total_semi;// ^ double total_flat;//waste_total * multiplier double total_semi;// ^ };This is the fragment of the code I was working on (I made it a dynamic array in the main)
void MainWindow::insert_to_database(){ int_paint.substrate = ui->Substrate->text(); int_paint.quantity =static_cast<int>(ui->Quantity->text()); QString UOM_info = ui->UOM->currentText(); if(UOM_info == "Sq Ft"){ int_paint.UOM = 'S'; } else if (UOM_info == "Ln Ft"){ int_paint.UOM = 'L'; } else if (UOM_info == "Ea"){ int_paint.UOM = 'E'; } int_paint.coats = ui->Coats->value(); //int_paint.sq_per_gal= ui->Material_type->; figure out the route to get the sq_per_gal calculate(); } //Thank you for helping!
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Hi! I'm really new to Qt, but i've been picking it up at a decent pace. I've been trying to use a class I added into the header file that was created in the program and make an array, but I couldn't get the class array to work. I tried changing it into a class , and that didn't work either. I did some snooping around in google and the documentation, but was unable to find anything. How does classes, and class arrays, work in Qt?
Class in the header file:
class int_paint { QString ID; //no usage other than programming QString unit; QString substrate; // area that is being painted QChar UOM; // unit of measure int quantity; double lf_conversion; //linear feet conversion int sq_per_gal; //square feet per gal double coats; bool f_or_s; double flat_per_unit; double semi_per_unit; int multiplier; //dependant on number of apartments double subtotal_flat; double subtotal_semi; int waste; double waste_total_flat; //subtotal * waste (waste must be entered as an int representing a %, conv it to decimal) double waste_total_semi;// ^ double total_flat;//waste_total * multiplier double total_semi;// ^ };This is the fragment of the code I was working on (I made it a dynamic array in the main)
void MainWindow::insert_to_database(){ int_paint.substrate = ui->Substrate->text(); int_paint.quantity =static_cast<int>(ui->Quantity->text()); QString UOM_info = ui->UOM->currentText(); if(UOM_info == "Sq Ft"){ int_paint.UOM = 'S'; } else if (UOM_info == "Ln Ft"){ int_paint.UOM = 'L'; } else if (UOM_info == "Ea"){ int_paint.UOM = 'E'; } int_paint.coats = ui->Coats->value(); //int_paint.sq_per_gal= ui->Material_type->; figure out the route to get the sq_per_gal calculate(); } //Thank you for helping!
@rocklionmba said in How do classes work in Qt?:
ui->Material_type->
What is ui->Material_type ?
maybe
int test = ui->Material_type->currentText().toInt(); -
@mrjj Material_type is a QComboBox that holds a list of paint. What I need to do there is, once the user listed the paint, it goes into the class of that paint and gets the square feet per gallon. I haven't done it yet because I wanted to test my program and to get it running before I continued.
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@mrjj Material_type is a QComboBox that holds a list of paint. What I need to do there is, once the user listed the paint, it goes into the class of that paint and gets the square feet per gallon. I haven't done it yet because I wanted to test my program and to get it running before I continued.
@rocklionmba
Ok. just ask away if needed.- How does classes, and class arrays, work in Qt?
same way as in plain C++;
However, all Widgets type ( GUI elements) are non copyable. ( QObject parent)
- How does classes, and class arrays, work in Qt?
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@mrjj
but how come when I doint_paint.substrate = ui->Substrate->text();,
I get the syntax error:C:\Users\\Documents\test\mainwindow.cpp:130: error: C2143: syntax error: missing ';' before '.'
C:\Users\\Documents\test\mainwindow.cpp:130: error: C2059: syntax error: '.'? -
@mrjj
but how come when I doint_paint.substrate = ui->Substrate->text();,
I get the syntax error:C:\Users\\Documents\test\mainwindow.cpp:130: error: C2143: syntax error: missing ';' before '.'
C:\Users\\Documents\test\mainwindow.cpp:130: error: C2059: syntax error: '.'?@rocklionmba You should have an object of type int_paint. Now you're trying to use the class name, it doesn't work. Have you programmed in javascript before? Because it's object-based and when you create an object it's a usable object immediately, while in C++ your write classes and you have to create objects out of them before you can use them.
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@rocklionmba You should have an object of type int_paint. Now you're trying to use the class name, it doesn't work. Have you programmed in javascript before? Because it's object-based and when you create an object it's a usable object immediately, while in C++ your write classes and you have to create objects out of them before you can use them.
@Eeli-K I completely forgot about that. I do C++ and I remember how to do that, but it just slipped over my head until you "pointed" it out. (mark it as my first programming pun.) Thank you so much!
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@Eeli-K tell one of the problem, another problem I found is all of the data member of your class are private, you cannot access them like that.
Study a great c++ book can help you a lot, it definitely worth your times if you want to leverage power of Qt, I recommend Programming -- Principles and Practice Using C++ for any level of the programmer, it is a book written by the father of c++.
