the_king
مدیرکل انجمن
کد زیر پس از تبدیل معادله Infix به Postfix، نتیجه را محاسبه و اعلام می کند :
کد:
program prg;
uses crt;
var
x:integer;
infix:string;
stack:array[1..50] of longint;
postfix:array[1..50] of longint;
equation:longint;
postfixi:integer;
stacki,i,j,k:integer;
function power(a,b:integer):integer;
var
i,j:integer;
begin
j:=1;
for i:=1 to b do
j:=j*a;
power:=j;
end;
function pop:integer;
begin
pop:=stack[stacki];
if stacki<1 then pop:=32750
else stacki:=stacki-1;
end;
procedure push(a:integer);
begin
stacki:=stacki+1;
stack[stacki]:=a;
end;
begin
clrscr;
postfixi:=1;
write (' Equation : ');
readln (infix);
write (' x :');
readln (x);
i:=1;
infix:='('+infix+')';
while (i<=length(infix)) do
begin
if ((infix[i]>='0') and (infix[i]<='9')) then
begin
j:=ord(infix[i])-48;
while ((infix[i+1]>='0') and (infix[i+1]<='9')) do
begin
i:=i+1;
j:=j*10+ord(infix[i])-48
end;
postfix[postfixi]:=j;
postfixi:=postfixi+1;
end
else begin
case infix[i] of
'x': begin
postfix[postfixi]:=x;
postfixi:=postfixi+1;
end;
'-': begin
k:=pop;
if (k<32756) then
begin
push(32751);
postfix[postfixi]:=k;
postfixi:=postfixi+1;
end
else begin
push(k);
push(32751);
end;
end;
'+': begin
k:=pop;
if (k<32756) then
begin
push(32752);
postfix[postfixi]:=k;
postfixi:=postfixi+1;
end
else begin
push(k);
push(32752);
end;
end;
'/': begin
k:=pop;
if (32752<k) and (k<32756) then
begin
push(32753);
postfix[postfixi]:=k;
postfixi:=postfixi+1;
end
else begin
push(k);
push(32753);
end;
end;
'*': begin
k:=pop;
if (32752<k) and (k<32756) then
begin
push(32754);
postfix[postfixi]:=k;
postfixi:=postfixi+1;
end
else begin
push(k);
push(32754);
end;
end;
'^': push(32755);
'(': push(32756);
')': begin
k:=pop;
while (k<32756) do
begin
postfix[postfixi]:=k;
postfixi:=postfixi+1;
k:=pop;
end;
end;
end;
end;
i:=i+1;
end;
for i:=1 to postfixi-1 do
begin
if postfix[i]<32750 then
push(postfix[i])
else begin
k:=pop;
j:=pop;
case postfix[i] of
32751 : push(j-k);
32752 : push(j+k);
32753 : push(j div k);
32754 : push(j*k);
32755 : push(power(j,k));
end;
end;
end;
equation:=pop;
writeln (' y = ',equation);
end.
