program StringManipulationExample;

uses
  SysUtils;

var
  originalStr, subStr: string;
  position: Integer;
begin
  originalStr := 'Hello, Delphi!';
  subStr := 'Delphi';
  
  // Find the position of a substring
  position := Pos(subStr, originalStr);
  Writeln('Position of "', subStr, '" in "', originalStr, '": ', position);
  
  // Extract a substring
  Writeln('Substring from position 8, length 6: ', Copy(originalStr, 8, 6));
  
  // Concatenate strings
  Writeln('Concatenated string: ', Concat(originalStr, ' How are you?'));
end.

program FileIOExample;

uses
  SysUtils, Classes;

var
  fileStream: TFileStream;
  buffer: array[1..20] of Char;
  bytesRead: Integer;
begin
  // Create and write to a file
  fileStream := TFileStream.Create('example.txt', fmCreate);
  try
    fileStream.WriteBuffer('Hello, Delphi!', 13);
  finally
    fileStream.Free;
  end;
  
  // Read from the file
  fileStream := TFileStream.Create('example.txt', fmOpenRead);
  try
    bytesRead := fileStream.Read(buffer, SizeOf(buffer));
    buffer[bytesRead + 1] := #0; // Null-terminate the string
    Writeln('Read from file: ', buffer);
  finally
    fileStream.Free;
  end;
end.

program DateTimeExample;

uses
  SysUtils, DateUtils;

var
  currentDate: TDateTime;
  futureDate: TDateTime;
begin
  currentDate := Now;
  Writeln('Current Date and Time: ', DateTimeToStr(currentDate));
  
  // Add 10 days to the current date
  futureDate := IncDay(currentDate, 10);
  Writeln('Date after 10 days: ', DateToStr(futureDate));
  
  // Calculate the number of days between two dates
  Writeln('Days between today and future date: ', DaysBetween(currentDate, futureDate));
end.

program SplitName;

uses
  SysUtils;

var
  fullName, firstName, lastName: string;
  spacePos: Integer;
begin
  Write('Enter your full name: ');
  Readln(fullName);
  
  spacePos := Pos(' ', fullName);
  if spacePos > 0 then
  begin
    firstName := Copy(fullName, 1, spacePos - 1);
    lastName := Copy(fullName, spacePos + 1, Length(fullName) - spacePos);
    Writeln('First Name: ', firstName);
    Writeln('Last Name: ', lastName);
  end
  else
    Writeln('Please enter a valid full name with a space between first and last name.');
end.

program ReadNamesFromFile;

uses
  SysUtils, Classes;

var
  fileStream: TFileStream;
  stringList: TStringList;
begin
  stringList := TStringList.Create;
  try
    fileStream := TFileStream.Create('names.txt', fmOpenRead);
    try
      stringList.LoadFromStream(fileStream);
      Writeln('Names from file:');
      Writeln(stringList.Text);
    finally
      fileStream.Free;
    end;
  finally
    stringList.Free;
  end;
end.

program DaysUntilBirthday;

uses
  SysUtils, DateUtils;

var
  birthDate, currentDate, nextBirthday: TDateTime;
  year, month, day: Word;
begin
  Write('Enter your birth date (YYYY-MM-DD): ');
  Readln(birthDate);
  
  currentDate := Now;
  DecodeDate(currentDate, year, month, day);
  nextBirthday := EncodeDate(year, MonthOf(birthDate), DayOf(birthDate));
  
  if nextBirthday < currentDate then
    nextBirthday := IncYear(nextBirthday, 1);
  
  Writeln('Days until next birthday: ', DaysBetween(currentDate, nextBirthday));
end.