DWORD部门Delphi / C ++

Question

So in C++ i can do something like:

DWORD count;

count = 3 / 1.699999;

cout << count;

which will result in:

1

Delphi however complains Cardinal and Extended mismatch.

var
  count: DWORD;
begin
  count := 3 / 1.6;
  Writeln(inttostr(count));

So i either have to round count := round(3 / 1.6) which results in:

2

or trunc count := trunc(3 / 1.6) which results in

1

Is trunc really the way to go? Is there maybe a compiler switch i would have to toggle?

You would think it's easy to google something like that but trust me it isn't.

Thanks for your time!

Answer 1

C/C++ only has one arithmetic division operator - / - but its behavior depends on the type of operands you pass to it. It can perform both integer division and floating point division .

Delphi has two arithmetic division operations - div for integer division , and / for floating point division .

Your C++ code is performing floating point division , and then assigning the result to a DWORD , which is not a floating point type, so the assignment truncates off the decimal point:

1 / 1.699999 is 1.764706920415836 , which truncates to 1 .

In Delphi, the / operator returns an Extended , which is a floating-point type. Unlike C/C++, Delphi does not allow a floating-point type to be assigned directly to an integral type. You have to use Round() or Trunc() .

In this case, the Delphi equivalent of your C++ code is to use Trunc() :

var
  count: DWORD;
begin
  count := Trunc(3 / 1.699999);
  Write(IntToStr(count));

Answer 2

The easiest is to use trunc(3 /1.699999). .

Another way is to use a previous multiplication before the division.

var
  count: DWORD;
begin
  count := 3;
  count := (count*1000000) div 1699999;
  Writeln(inttostr(count));

Of course, to avoid overflow, count should be < maxInt div 1000000 .