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    Trunc

    Truncate a floating point value.

    Declaration

    Source position: mathh.inc line 131

    function Trunc(d: ValReal) : Int64;

    Description

    Trunc returns the integer part of X, which is always smaller than (or equal to) X in absolute value.

    Errors

    An invalid floating point operation error may occur in one of several conditions:

    • Infinity or NegInfinity is specified.
    • Nan is specified.
    • X is out of the valid range of integers.

    See also

    Name Description
    Frac Return fractional part of floating point value.
    Int Calculate integer part of floating point value.
    Round Round floating point value to nearest integer number.

    Example

    Program Example70;

{ Program to demonstrate the Trunc function. }

begin
  Writeln (Trunc(123.456));  { Prints 123  }
  Writeln (Trunc(-123.456)); { Prints -123 }
  Writeln (Trunc(12.3456));  { Prints 12   }
  Writeln (Trunc(-12.3456)); { Prints -12  }
end.

    Example

    program ex124;

{
  Example to show various error conditions for the Trunc() function.
  SysUtils is used to convert the runtime error to an exception that can be caught
  Math is used to have access to Nan and (Neg)Infinity
 
}

{$mode objfpc}
{$h+}
uses

  sysutils, math;
var
  D: Double;
  Q: QWord;
  L: Int64;
begin
  D := 2.0 * High(QWord);
  try
    Q := Trunc(D);
  except
    on E: Exception do writeln(E.ClassName,': ',E.Message);  //EInvalidOp: Invalid floating point operation
  end;
  D := NaN;
  try
    Q := Trunc(D);
  except
    on E: Exception do writeln(E.ClassName,': ',E.Message);  //EInvalidOp: Invalid floating point operation
  end;
  D := Infinity;
  try
    Q := Trunc(D);
  except
    on E: Exception do writeln(E.ClassName,': ',E.Message);  //EInvalidOp: Invalid floating point operation
  end;
  D := NegInfinity;
  try
    Q := Trunc(D);
  except
    on E: Exception do writeln(E.ClassName,': ',E.Message);  //EInvalidOp: Invalid floating point operation
  end;
  D := -2.0 * High(QWord);
  try
    L := Trunc(D);
  except
    on E: Exception do writeln(E.ClassName,': ',E.Message);  //EInvalidOp: Invalid floating point operation
  end;
end.