IF Then problem

[MLNorton]

I have a Delphi 2007 procedure to determine the numerical value of the first Monday in the current year. My code is as follows:
Var
WeekDay: integer;
MyDate: TDateTime;
begin
Decodedate(Date,Y,M,D);
MyDate := EncodeDate(Y,1,1);
WeekDay := DayOfWeek(MyDate);
if WeekDay = 1
then
MyDate := MyDate + 1;
If WeekDay = 2
Then
MyDate := MyDate;
If WeekDay = 3
Then
MyDate := MyDate + 6;
If WeekDay = 4
Then
MyDate := MyDate + 5;
If WeekDay = 5
Then
MyDate := MyDate + 4;
If WeekDay = 6
Then
MyDate := MyDate + 3;
if WeekDay = 7
Then
MyDate := MyDate + 2;

For 2012 January 1st My Date is 4909 and WeekDay is 2. When I iterate through the code the line MyDate := MyDate + 1; is skipped.

Why? What is causing this?

 

[majlumbo]

This function should return the first Monday of a given year (input the desired year), from there you can get the numerical value of the date.

function FirstMondayOfYear(Year: Word): TDate;
begin
   case DayOfWeek(EncodeDate(year, 1, 1)) of
      1: Result := EncodeDate(year, 1, 2);
      2: Result := EncodeDate(year, 1, 1);
      3: Result := EncodeDate(year, 1, 7);
      4: Result := EncodeDate(year, 1, 6);
      5: Result := EncodeDate(year, 1, 5);
      6: Result := EncodeDate(year, 1, 4);
      else
         Result := EncodeDate(year, 1, 3);
   end;
end;

 

[imex]

MLNorton,

This line of code is executed only when WeekDay is equal to 1.

I hope this help.


Imobiliárias em Guarulhos

 

[towerbase]

Perhaps a simpler function would be

[b]function[/b] FirstMondayInYear( datum: TDateTime ): TDateTime;
[b]const[/b]
  Monday = 2;
[b]begin[/b]
  result := EncodeDate( YearOf( datum ), 1, 1 );  // Assume 1 Jan of year of supplied date is a Monday.
  [b]while[/b] DayOfWeek( result ) <> Monday [b]do[/b]          // While this is not a Monday
    result := result + 1;                         // Add one day to date
[b]end[/b];

Andrew

 

[MLNorton]

Problem solved. Thanks.