如何在C ++ Builder中使用Delphi“in”运算符

Question

I'm a newbie programmer. I need to use Delphi's in operator in C++ Builder XE like this:

if (dgColLines in DBGrid->Options)
    // include vertical lines in total (one per column)
    TotalColumnWidth = TotalColumnWidth + ColumnCount;

if (dgColLines **in** DBGrid->Options)

How to do that in C++ Builder?

Thanks in advance.

Answer 1

Use the Contains method to check if a set contains a specific element:

if( DBGrid->Options.Contains(dgColLines) )
  TotalColumnWidth = TotalColumnWidth + ColumnCount;

Answer 2

Looking the the property in question, TDBGrid.Options , its type is TDBGridOptions which is defined as:

typedef System::Set<TDBGridOption, TDBGridOption::dgEditing,
    TDBGridOption::dgTitleHotTrack> TDBGridOptions;

As you can see, C++ Builder uses the template System::Set<T, minEl, maxEl> to emulate Delphi set types.

All of the functionality available using the built in Delphi set operators is exposed through the methods of Set . Specifically to this question, set membership is testing using Contains() .