{
The DATA:
20081231 Betty 03/09/1978
 
The programm
}
program solution;
 
type Tmember = record
                  id:longint;
                  name:string;
                  day:1..31;
                  month:1..12;
                  year:1900..3000;
               end;
 
 
var infile:file of Tmember;
    infilename:string;
    someone:Tmember;
    searching:boolean;
    idn:longint;
 
 
begin
     infilename:='C:\myfile.dat';
     write('Member ID > ');
     readln(idn);
     searching:=false;
     assign(infile,infilename);
     reset(infile);
     while not eof(infile) do begin
           read(infile,someone);
           if idn=someone.id then begin
           writeln('Name:',someone.name);
           writeln('Date of birth: ',someone.day,'-',someone.month,'-',someone.year);
           searching:=true;
           end;
     end;
     if searching=false then
     writeln(someone.id,' cannot be found.');
     close(infile)
end.

 
{full commented version created by FlamingClaw 2009}
program solution;
 
type Tmember = record
                  id:longint;
                  name:string;
                  day:1..31;
                  month:1..12;
                  year:1900..3000;
               end;
 
 
var infile:file of Tmember; {this file can contain records only...}
    infilename:string;      {stores the file's name ,path,and extension}
    someone,base:Tmember;   {two records,someone for read in,base for write in}
    searching:boolean;      {checking search,done it or not...}
    idn:longint;            {we search by id,and its type is longint same as in the record's field}
 
{here begins the main program}
begin
     {the file named myfile.dat and placed to the C:\ drive}
     infilename:='C:\myfile.dat';
     write('Member ID > ');
     {here catch the answer of the user}
     readln(idn);
     {searching is set to false}
     searching:=false;
     {assign the file var to a file,that is set to infilename }
     assign(infile,infilename);
     {create the data file,or if it is exists then delete its contents!}
     rewrite(infile);
     {fill the record's fields with these data:
     20081231 Betty 03/09/1978 }
     with (base) do begin
                      id:=20081231;
                      name:='Betty';
                      day:=03;
                      month:=09;
                      year:=1978;
     end;
     {first write the data file contents}
     write(infile,base);
     {file opening for reading...}
     reset(infile);
     {loop will over and over till we reach the end of the file}
     while not eof(infile) do begin
           {read one record,by round}
           read(infile,someone);
           {if the catched answer is equal to the readed record' id field then}
           if idn=someone.id then begin
           {write out the results to the screen,used by the record}
           writeln('Name:',someone.name);
           writeln('Date of birth: ',someone.day,'-',someone.month,'-',someone.year);
           {and the searching was success,everybody happy !}
           searching:=true;
           end;
     end;
     {if there were not success the loop then,search is stay false}
     if searching=false then
     {and notify the user...}
     writeln(someone.id,' cannot be found.');
     {it is not matter that the process was success or not close the file}
     close(infile);
     readln;{waits for pressing the enter button}
end.  {and here the end of the program}