** PROGRAM TITLE: FILE_CLOSE

(******************************************************
** PROGRAM TITLE: FILE_CLOSE_DEMONSTRATION
**
** WRITTEN BY: Raymond E. Penley
** DATE WRITTEN: 22 JAN 1980
** Modified for Pascal/Z vers 3.0
** 25 June 1980
**
** SUMMARY:
** Demonstrate the three methods of closing files
** with Pascal.
**
** 1. Using a file variable in a block.
** 2. Reusing a file variable with another file
** identifier (file name) to close the currently
** open file before opening the new file.
** 3. Normal program termination will close ALL
** open files. (This is NOT the preferred method)
**
*******************************************************)
PROGRAM FCLOSE;
var
IX : INTEGER;
wrk1 : TEXT; { Global file descriptor <FCB> }

Procedure PAUSE;
var du: char;
begin
write('Press return to continue');
readln(du);
end;

Procedure CLEAR;
var ix: 1..25;
begin
for ix:=1 to 25 do writeln;
end;

PROCEDURE A;
VAR F1 : TEXT;
BEGIN
CLEAR;
writeln('FILE CLOSE METHOD #1');
writeln;
writeln('USING A FILE VARIABLE LOCAL TO A "BLOCK"');
writeln('WILL CLOSE THE FILE(S) UPON EXIT OF THE BLOCK');
writeln('This is the preferred method!');
writeln;
writeln(' PROCEDURE A;');
writeln(' VAR F1 : TEXT;');
writeln(' BEGIN');
writeln(' REWRITE(''CTESTA.$$$'',F1);');
writeln(' ... BODY OF PROCEDURE ...');
writeln(' END; { CLOSE(F1) }');
writeln;
writeln('UPON EXITING THIS PROCEDURE WE WILL CLOSE');
writeln('THE FILE ''CTESTA.$$$'' AND FIX IT ON THE DIRECTORY');
REWRITE('CTESTA.$$$', F1);
writeln(F1, 'PROCEDURE A');
writeln;
PAUSE;
END; { CLOSE(F1) }

Procedure B;
begin
CLEAR;
REWRITE('CTESTQQ.$$$',WRK1);
writeln(WRK1,'CTESTQQ.$$$ THIS IS CURRENTLY OPEN FILE');
writeln('FILE CLOSE METHOD #2');
writeln;
writeln('Reusing the same file variable with a new file');
writeln('identifier <file name> will close the currently');
writeln('open file before opening the new file');
writeln;
writeln(' begin');
writeln(' REWRITE(''CTESTQQ.$$$'',WRK1);');
writeln(' writeln(WRK1,''THIS IS THE CURRENTLY OPEN FILE'');');
writeln(' writeln(''NOW TO CLOSE CTESTQQ.$$$ AND OPEN'');');
writeln(' writeln(''CTESTZZ.$$$'');');
writeln(' REWRITE(''CTESTZZ.$$$'',WRK1);');
writeln(' writeln(''CTESTZZ.$$$ IS NOW THE CURRENT FILE'');');
writeln(' end;');
writeln;
REWRITE('CTESTZZ.$$$',WRK1);
writeln(WRK1,'CTESTZZ.$$$ IS NOW THE CURRENT FILE');
writeln;
PAUSE;
end;

BEGIN
CLEAR;
writeln('FILE CLOSE DEMONSTRATION FOR PASCAL/Z');
writeln('by Raymond E. Penley');
FOR IX:=1 TO 12 DO writeln;
FOR IX:=1 TO 5000 DO {DUMMY} ;
A; {--- Method #1 ---}
B; {--- Method #2 ---}
{--- Method #3 ---}
CLEAR;
writeln('FILE CLOSE METHOD #3');
writeln;
writeln('This is really the simplist method. Any files still');
writeln('open at program termination will be closed. This is');
writeln('the most dangerous method in that a power failure or a');
writeln('disk failure while the program is running will leave');
writeln('your file nowhere.');
writeln('The file "CTESTZZ.$$$" is still open at this time.');
writeln('When this program terminates it will be fixed on the');
writeln('directory.');
writeln;
PAUSE;
writeln;writeln;writeln;writeln;
End{of file close demo}{ CLOSE(wrk1) }.