Hello
I use turbo_pascal language for learning. I write a program (T3ch18.pas)
which use two units – (Uadd_pro.pas) and (Un3ch 18.pas).
In unit Uadd_pro.pas , I used procedure ask. It works true when I test it
only, but when I use them together, above mentioned procedure in line –
readLn- causes error and cpu abrupts running and finished running it.
If it is possible for you, please help me to solve this problem.
For run (T3ch18.pas) after running and choosing 1 for your choice in menu
choice, it wants from you a positive- integer number as number of stuff and a
real value as price of stuff and a name as vender, after then it ask you that
if you want to continue or not and in this stage error will occur.
Thanks for your attention.
program T3ch18;
{an answer for tamrine 3 of chapter 18.
writer :Akbar Zamani date:1388/3/15}
uses uadd_pro,un3ch18,crt;
var myQueue :stuff_queue;
answer :char;
newstuff :stuff_data;
chose :integer;
begin{T3ch18}
clrscr;
myQueue.Init;
repeat
writeLn ('1 for add to queue ');
writeLn ('2 for pop ');
writeLn ('3 for send cost for an order');
writeLn ('4 for exit ');
repeat
write (' chose your action >');
readLn (chose)
until chose in [1..4];
case chose of
1: begin{add}
answer:='y';
writeLn (' adding new stuff to queue ');
while answer in ['y', 'Y'] do
begin{while}
myQueue.makestuff(newstuff);
myQueue.push(newstuff);
{myQueue.}ask('do you want continue adding new stuff>', answer)
end{while}
end;{add}
2: myQueue.pop(newstuff);
3: myQueue.send_cost(newstuff);
4: {exit}
end;{case}
until chose= 4;
writeLn (' sending an order');
end.{T3ch18}unit un3ch18;
interface
uses crt;
type
status =(s, o);
stuff_data =record
stuff_status :status;
number :longInt;
cost :real;
vender :string[20]
end;{stuff_data}
stuff_pointer = ^stuff;
stuff = record
stuff_info:stuff_data;
link :stuff_pointer
end;{stuff}
stuff_queue = object
procedure Init;
procedure push(newstuff{in}:stuff_data);
procedure pop (var newstuff{out}:stuff_data);
function getPrice :real;
procedure display;
{procedure ask(x}{in}{:string;var y_answer}{out}{:char); }
procedure send_cost(newstuff{in}:stuff_data);
procedure makestuff(var newstuff{out}:stuff_data);
private
first, last :stuff_pointer ;
procedure dodisplay (data{in}:stuff_data);
end;{stuff_queue}
implementation
procedure stuff_queue.Init;
{}
begin{Init}
first := nil;
last := nil
end;{Init}
{procedure stuff_queue.ask(x}{in}{:string;var y_answer}{out}{:char);}
{var next_ch :char; {next_char as answer}
{begin}{ask}
{repeat
write (x:length(x));
readLn (next_ch)
until next_ch in ['y', 'Y', 'n', 'N' ] ;
y_answer := next_ch
end;}{ask}
procedure stuff_queue.dodisplay(data:stuff_data);
{for displaying content of data.
pre :none.
post:content of data is shown.}
begin{dodisplay}
with data do
begin{with}
write (number:25);
if stuff_status = s then write (' status= s ':15)
else if stuff_status = o then write (' status= o ':15)
else writeln(' An error has been occured. ');
write ('cost=',cost:10,'$') ;
writeLn ('vender =',vender :20)
end{with}
end;{dodisplay}
function stuff_queue.getPrice :real;
{for calculate price of a order.
pre :stuff_queue is defined.
post:price is product of this function and is defined.}
var p :stuff_pointer;
begin{getPrice}
p:=first;
if first =nil then writeLn ('error, queue is empty ')
else getPrice := p^.stuff_info.number*p^.stuff_info.cost
end;{getprice}
procedure stuff_queue.send_cost(newstuff{in}:stuff_data);
{for making information and price of an order.
pre : newstuff was defined.
post: price and information about the stuff is displayed.}
begin{send_cost}
with newstuff do
begin{with}
write ('status =', 'o',' ','number =',number,' ','cost =',cost);
writeLn (' ','vender = ',vender);
writeLn ('total price = ',getPrice)
end{with}
end;{send_cost}
procedure stuff_queue.push(newstuff{in}:stuff_data);
{for adding a new stuff to a queue of stuffs.
pre : newstuff was defined.
post:newstuff is added to queue of stuffs.}
var p :stuff_pointer;
begin{push}
p^.link :=nil;
p^.stuff_info :=newstuff;
last^.link := p;
last := p
end;{push}
procedure stuff_queue.pop (var newstuff{out}:stuff_data);
{for omit a stuff from a queue.
pre : queue was defined.
post: newstuff is defined and this stuff is omitted from queue.}
var p :stuff_pointer;
begin{pop}
p:=first;
newstuff := p^.stuff_info;
first := first^.link;
p^.link :=nil;
if p<> nil then dispose (p)
end;{pop}
procedure stuff_queue.makestuff(var newstuff{out}:stuff_data);
{for create a stuff}
begin{makestuff}
with newstuff do
begin{with}
stuff_status := s;
write ('number of stuff>');
readLn (number);
write ('cost of each stuff>');
readLn (cost);
write ('vender> ');
readLn (vender)
end{with}
end;{makestuff}
procedure stuff_queue.display;
{for display contents of a queue.
pre : queue is defined.
post:none.}
var p :stuff_pointer;
begin{display}
p := first;
while p<>nil do
begin{while}
dodisplay(p^.stuff_info);
p:= p^.link
end{while}
end;{display}
end.{un3ch18}unit uadd_pro;
interface
uses crt;
procedure ask(x{in}:string;var y_answer{out}:char);
implementation
procedure ask(x{in}:string;var y_answer{out}:char);
var next_ch :char; {next_char as answer}
begin{ask}
repeat
write (x:length(x));
readLn (next_ch)
until next_ch in ['y', 'Y', 'n', 'N' ] ;
y_answer := next_ch
end;{ask}
end.{add_pro}_______________________________________________
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