Pascal News

8-Sep-81
Yet Another Extension
x write(field,xval:vl);
end;
Posit(screen,field,vx,vy);
init(field);
write(field,name:nl,' (' ,fx:l,')');
Posit(screen,field,nx,ny);
end:
get (table) ;
end:
end;
Dump(output,screen);
end;
begin { MoneyMarketIII }
InlO:=ln(10.0);
{ Determine filnum }
dread(table,filnum,filcon);
connect (data,filcon.name) " external is standard, w'r • .i not connect? }:
reset(data) { Requires random-I/O ability in run-time environment );
{ Po"j.tion datafile and determine page}
FiIIScreen(output,table,data,filnum,page,ScreenHeight,ScreenWidth);
{ Other processing }
end.
~!:~~t:.~inU~!l~
The main point of this essay (whenever it pretended to have one)
has been that Pascal has always had string-handling ability and that
the addition of a few functions could provide enough improvement to
obviate any need for a heavyweight boxing match to decide which dynamic
array description method should be used. However, the example program
is in many ways redundant, since the same kinds of code sequences
appear repeatedly. For this reason the following suggested list of
string functions i8 proposed. Implementing them in assembly would
remove the restriction that the files must be of a specific type.
The "type" File, as used below, reflects this generic capability,
available only to intrinsic procedures.
procedure Append(var output,input:File);
begin
reset(input) ;
while NOT eof(input) do begin
write(output,inputt);
get(input);
endi
t:!nd;
procedure Copy (var output,input:File);
begin
i.nit(output);
Append(output,input);
end;
8-Sep-Sl
Yet Another Extension
procedure Posit{var output,input:File; sequence: Integer) :
begin
seek(output,sequence);
Append(output,input):
end;
procedure Switch(vat output,input:File):
begi"
Copy {output, input) ;
init(input) ! Actually, since the internal pointers are being
switched, the input file would be left undefined (closed). }
end;
procedure Extract(var input,output:File; loc,leng:Integer);
var x:lntegeri
begin
seek(input,loc) ;
init(output):
for x:=l to leng do begin
write(output,inputt);
get (input) ;
end;
end;
procedure Insert(var output,input:File; sequence: Integer) ;
var
temp: File;
x : Integer:
begin
Extract (output,temp,O,sequence) ;
Append(temp,input);
while NOT eof(output) do begin
write(temp,outputt);
get (output) ;
end;
copy(output,temp):
end;
function Compare (var left,right:File) :1•• 3;
label 1;
begin
reset(left) ;
reset (right) ;
1:
if eof(left) then compare:=3-ord(eof(right»
else if eof(right) then COmpare:=l+ord(eof(left»
else if lefttrightt then Compare:=1+2*ord(leftt