System::SharedPtr<Project> project = CreateTestProject();
System::SharedPtr<Task> task = project->get_RootTask()->get_Children()->GetById(1);
    
System::SharedPtr<ExtendedAttributeDefinition> numberDefinition = ExtendedAttributeDefinition::CreateTaskDefinition(Aspose::Tasks::ExtendedAttributeTask::Number1, nullptr);
project->get_ExtendedAttributes()->Add(numberDefinition);
    
System::SharedPtr<ExtendedAttribute> numberAttribute = numberDefinition->CreateExtendedAttribute();
task->get_ExtendedAttributes()->Add(numberAttribute);
    
// Set ProjDateDiff formula and print extended attribute value
numberDefinition->set_Formula(u"ProjDateDiff(\"03/23/2015\",\"03/18/2015\")");
System::Console::WriteLine(numberAttribute->get_NumericValue());
numberDefinition->set_Formula(u"ProjDateDiff(\"03/23/2015\",\"03/25/2015\")");
System::Console::WriteLine(numberAttribute->get_NumericValue());
    
System::SharedPtr<ExtendedAttributeDefinition> dateDefinition = ExtendedAttributeDefinition::CreateTaskDefinition(Aspose::Tasks::ExtendedAttributeTask::Date1, nullptr);
project->get_ExtendedAttributes()->Add(dateDefinition);
System::SharedPtr<ExtendedAttribute> dateAttribute = dateDefinition->CreateExtendedAttribute();
task->get_ExtendedAttributes()->Add(dateAttribute);
    
System::SharedPtr<ExtendedAttributeDefinition> durationDefinition = ExtendedAttributeDefinition::CreateTaskDefinition(Aspose::Tasks::ExtendedAttributeTask::Duration4, u"Custom duration field");
project->get_ExtendedAttributes()->Add(durationDefinition);
System::SharedPtr<ExtendedAttribute> durationAttribute = durationDefinition->CreateExtendedAttribute();
task->get_ExtendedAttributes()->Add(durationAttribute);
    
System::SharedPtr<ExtendedAttributeDefinition> textDefinition = ExtendedAttributeDefinition::CreateTaskDefinition(Aspose::Tasks::ExtendedAttributeTask::Text5, u"Custom text field");
project->get_ExtendedAttributes()->Add(textDefinition);
System::SharedPtr<ExtendedAttribute> textAttribute = textDefinition->CreateExtendedAttribute();
task->get_ExtendedAttributes()->Add(textAttribute);
    
// Set ProjDateSub formula and print extended attribute value
dateDefinition->set_Formula(u"ProjDateSub(\"3/19/2015\", \"1d\")");
System::Console::WriteLine(System::ObjectExt::Box<System::DateTime>(dateAttribute->get_DateValue()));
    
// We can set ProjDurConv formula to duration-valued attribute as well as to text-valued attribute.
    
// Set ProjDurConv formula to duration-valued extended attribute and print its value.
durationDefinition->set_Formula(u"ProjDurConv([Duration], pjHours)");
System::Console::WriteLine(System::ObjectExt::Box<Duration>(durationAttribute->get_DurationValue()));
    
// Set ProjDurConv formula to text-valued extended attribute and print its value.
textDefinition->set_Formula(u"ProjDurConv([Duration], pjHours)");
System::Console::WriteLine(textAttribute->get_TextValue());
    
textDefinition->set_Formula(u"ProjDurConv([Duration], pjWeeks)");
System::Console::WriteLine(textAttribute->get_TextValue());
    
// Set Second formula and print entended attribute value
numberDefinition->set_Formula(u"Second(\"4/21/2015 2:53:41 AM\")");
System::Console::WriteLine(numberAttribute->get_NumericValue());
    
// Set Weekday formula and print entended attribute value
numberDefinition->set_Formula(u"Weekday(\"24/3/2015\", 1)");
System::Console::WriteLine(numberAttribute->get_NumericValue());
numberDefinition->set_Formula(u"Weekday(\"24/3/2015\", 2)");
System::Console::WriteLine(numberAttribute->get_NumericValue());
numberDefinition->set_Formula(u"Weekday(\"24/3/2015\", 3)");
System::Console::WriteLine(numberAttribute->get_NumericValue());