Truncate float without rounding

[WojTec]

How to truncate float number to n digits after point, but without rounding it, for example 147.258 --> 147.25 (input is extended) :wall:

[Bernhard Geyer]

For two digits:

Delphi-Quellcode:

myVal := 147.258;
myVal := Trunc(myVal*100)/100;

[kamel08]

// For n digits:

Delphi-Quellcode:

Function RoundedReal(n:Double; count:Integer):Double;
// count: Anzahl der Stellen nach dem Komma
var multi:Double;
begin
     multi := IntPower(10, count);
     n := Round(n * multi);
     result := n / multi;
end;

// IntPower erfordert die Unit 'Math'

[WojTec]

Thanks you, now I understand how it working :)

BTW: if input is Extended and want to truncate to 0 digits (like Round), output should be what type? Cardinal?

[Furtbichler]

The output will be extended same way. You have to convert it to an integer yourself.

[Medium]

For a totally general case, an Int64 would cover the largest range out of the integer types, that might be put in by an Extended. Cardinal most notably misses the sign. It depends on what you use the number for if you could use smaller types as output. (But even an Int64 can not cover the full range of an Extended by design - not without some rather wild re-mappings.)

[sx2008]

It seems that the Int()-function is rather unknown to most programmers.

Delphi-Quellcode:

Function RoundedReal(n:Double; decimalplaces:Integer):Double;
var multi:Double;
begin
  Assert(decimalplaces >=0);
  multi := IntPower(10, decimalplaces);
  Result := Int(n * multi) / multi;
end;

[WojTec]

I know Int() :) IF we are here, could you explain me differences between Round(), Trunc() and Int()?

[Sir Rufo]

Zitat:

Zitat von WojTec (Beitrag 1242316)

I know Int() :) IF we are here, could you explain me differences between Round(), Trunc() and Int()?

If we are here, did you read the documentation about Round, Trunc, Int, Floor, Ceil?
Why I have a NO in my mind? :roll:

[Furtbichler]

Look it up in google, I just did it and it worked (google) so it's not down and will help you same way.