Program prueba1;
uses Estructu;
Var Pila1:Pila; Fila1,Completa:Fila;
Begin
Inicfila (Completa);
readpila(Pila1);
readfila(Fila1);
While (not pilavacia(Pila1) and not filavacia(Fila1)) do
begin
if (tope(Pila1) > primero(Fila1)) then
begin
agregar(Completa, desapilar(Pila1))
else
if (tope(Pila1) < primero(Fila1)) then
begin
agregar(Completa, extraer(Fila1))
else
if (tope(Pila1) = primero(Fila1)) then
begin
agregar(Completa, desapilar(Pila1));
agregar(Completa, extraer(Fila1))
end
end
end
end
write('El resultado final de Completa es');
Writefila(Completa);
End.
The purpose of the program would be to organise in Completa all the variables from Pila1 and Fila1 in order from first to last.
I don't know what I'm doing wrong and would appreciate the help
You are not using if ... then ... else and begin ... end correctly.
There is the concept of a block, which is started with begin and ended with end. Anywhere where a single statement is expected, you can put a block instead. This is also the case for if <condition> then <statement> else <statement>;.
So, this code is valid:
if something() then
stuff
else
stuff;
...as is this:
if something() then
begin
stuff;
moreStuff;
end
else
begin
otherStuff;
moreOtherStuff;
end;
However, this (which you are using) is not:
if something() then
begin
stuff // I guess here you omitted the semicolon because you correctly remembered
// that there shouldn't be a semicolon before `else`, but...
else // WRONG, this is in the middle of the block!
otherStuff;
end;
To see why, let's fix the indention to match the logical interpretation of this code:
if something() then
begin
stuff
else // ????????
otherStuff;
end;
You get an error since begin ... else ... end is not a valid construct. Since there is a begin but then no end before the else, your else is in the middle of the then block which makes no sense.
Make sure to end your block before starting the else part, and then begin a new block.
Related
I want to use goto statement in Mysql stored procedure in such manner that I execute my cursor whenever condition become true once again.
This is a sample code only, I just looking for goto statement
BLOCK_BACKLOG:begin
declare backlgId, oldCOR, oldATR,oldCourse,oldATR,isFormFilled,nextParentId int;
declare backlogNoMoreRow boolean default false;
Label : TestLineStart
declare backlogCur cursor for select bcklg.id,cor.id,atr.id,cr.id,atr.obtainedMarks,atr.isFormFilled,atr.parentRegistration_id
from train bcklg,bus cor,fliet atr,fair co,distance cr
where bcklg.courseofferingregistration_id=cor.id and cor.academictermregistration_id=atr.id and cor.courseoffering_id=co.id and co.course_id=cr.id
and bcklg.isDeleted is false and atr.id=parentId;
declare continue handler for not found set backlogNoMoreRow=true;
open backlogCur;
LOOP_BACKLOG: loop
fetch backlogCur into backlgId, oldCOR, oldATR,oldCourse,oldATRMarks,isFormFilled,nextParentId;
if backlogNoMoreRow then
close backlogCur;
leave LOOP_BACKLOG;
end if;
if isFormFilled==0 then
parentId=nextParentId;
GOTO TestLineStart;
end if;
You can use a LOOP on the outer block based on the value for variable isFormFilled.
Following change may help you.
-- Label : TestLineStart
TestLineStart: LOOP
-- other part of your SP as it is
and make following change:
if isFormFilled==0 then
parentId=nextParentId;
-- GOTO TestLineStart;
else
leave TestLineStart;
end if;
You have to close all loop statements properly.
This post is related to the my previous post related to FFT.
FFT implemetation in Verilog: Assigning Wire input to Register type array
I want to assign output of first stage to input of second stage of FFT butterfly modules. I have to re-order the output of first stage according to input of second stage. Here is my code to implement the swapping.
always# (posedge y_ndd[0] or posedge J)
begin
if(J==1'b1)
begin
for (idx=0; idx<N/2; idx=idx+1)
begin
IN[2*idx] <= X[idx*2*X_WDTH+: 2*X_WDTH];
IN[2*idx+1] <= X[(idx+N/2)*2*X_WDTH+: 2*X_WDTH];
end
end
else
begin
level=level+1;
modulecount=0;
for(jj=0;jj<N;jj=jj+(2**(level+1)))
begin
for (jx=jj; jx<jj+(2**level); jx=jx+1)//jj+(2**level)
begin
IN[modulecount] <=OUT[jx];
IN[modulecount+1] <=OUT[jx+(2**level)];
modulecount=modulecount+1;
end
end
end
end
When I synthesize this, It gives 2 errors.
ERROR:Xst:891 - "Network.v" line 161: For Statement is only supported when the new step evaluation is constant increment or decrement of the loop variable.
ERROR:Xst:2634 - "Network.v" line 161: For loop stop condition should depend on loop variable or be static.
Can't we use non-constant increment and non-static stop coditions?
If that so, how we handle this.
Any help is appreciated.
Thanks in advance.
Synthesis tools unroll loops in order to synthesize the circuit. Therefore, only loops that iterate a constant number of times, whose constant is known at compile/elaboration time are synthetisable.
When the stop value is not known, you can assume a maximum number of iterations and use that as the stop condition. Then add the original stop condition as a conditional statement inside the loop:
for (jx=jj; jx < MAX_LOOP_ITERATION; jx=jx+1)//jj+(2**level)
begin
if (jx<jj+(2**level)) // <---------- Add stop condition here
begin
IN[modulecount] <=OUT[jx];
IN[modulecount+1] <=OUT[jx+(2**level)];
modulecount=modulecount+1;
end
end
If N is not a constant, the outer loop should also be fixed using a similar conditional statement. You also need to fix the increment value and each time add a constant value. Use a conditional statement to check if jj==jj+(2**(level+1))
Obviously, you need to be careful as a high max number may increase your worst case delay and the minimum clock cycle time.
//ll,level,K has to be declare.
always# (posedge y_ndd[0] or posedge J)
begin
if(J==1'b1)
begin
for (idx=0; idx<N/2; idx=idx+1)
begin
IN[2*idx] <= X[idx*2*X_WDTH+: 2*X_WDTH];
IN[2*idx+1] <= X[(idx+N/2)*2*X_WDTH+: 2*X_WDTH];
end
end
else
begin
ll=ll+1;
modulecount=0;
for(level=0;level<K;level=level+1) //K time you need to execute
begin
if(ll==level)
begin
for(jj=0;jj<N;jj=jj+(2**(level+1)))
begin
for (jx=jj; jx<jj+(2**level); jx=jx+1)
begin
IN[modulecount] <=OUT[jx];
IN[modulecount+1] <=OUT[jx+(2**level)];
modulecount=modulecount+1;
end
end
end
end
//ll=ll+1;
end
end
You can try this. It has to work. But problem is outer loop will execute K times.
I need to go through a HTML string and replace characters with 0 (zero), except tags, spaces and line breaks. I created this code bellow, but it is too slow. Please, can someone help me to make it faster (optimize)?
procedure TForm1.btn1Click(Sender: TObject);
var
Txt: String;
Idx: Integer;
Tag: Boolean;
begin
Tag := False;
Txt := mem1.Text;
For Idx := 0 to Length(Txt) - 1 Do
Begin
If (Txt[Idx] = '<') Then
Tag := True Else
If (Txt[Idx] = '>') Then
Begin
Tag := False;
Continue;
end;
If Tag Then Continue;
If (not (Txt[Idx] in [#10, #13, #32])) Then
Txt[Idx] := '0';
end;
mem2.Text := Txt;
end;
The HTML text will never have "<" or ">" outside tags (in the middle of text), so I do not need to worry about this.
Thank you!
That looks pretty straightforward. It's hard to be sure without profiling the code against the data you're using, (which is always a good idea; if you need to optimize Delphi code, try running it through Sampling Profiler first to get an idea where you're actually spending all your time,) but if I had to make an educated guess, I'd guess that your bottleneck is in this line:
Txt[Idx] := '0';
As part of the compiler's guarantee of safe copy-on-write semantics for the string type, every write to an individual element (character) of a string involves a hidden call to the UniqueString routine. This makes sure that you're not changing a string that something else, somewhere else, holds a reference to.
In this particular case, that's not necessary, because you got the string fresh in the start of this routine and you know it's unique. There's a way around it, if you're careful.
CLEAR AND UNAMBIGUOUS WARNING: Do not do what I'm about to explain without making sure you have a unique string first! The easiest way to accomplish this is to call UniqueString manually. Also, do not do anything during the loop that could assign this string to any other variable. While we're doing this, it's not being treated as a normal string. Failure to heed this warning can cause data corruption.
OK, now that that's been explained, you can use a pointer to access the characters of the string directly, and get around the compiler's safeguards, like so:
procedure TForm1.btn1Click(Sender: TObject);
var
Txt: String;
Idx: Integer;
Tag: Boolean;
current: PChar; //pointer to a character
begin
Tag := False;
Txt := mem1.Text;
UniqueString(txt); //very important
if length(txt) = 0 then
Exit; //If you don't check this, the next line will raise an AV on a blank string
current := #txt[1];
dec(current); //you need to start before element 1, but the compiler won't let you
//assign to element 0
For Idx := 0 to Length(Txt) - 1 Do
Begin
inc(current); //put this at the top of the loop, to handle Continue cases correctly
If (current^ = '<') Then
Tag := True Else
If (current^ = '>') Then
Begin
Tag := False;
Continue;
end;
If Tag Then Continue;
If (not (current^ in [#10, #13, #32])) Then
current^ := '0';
end;
mem2.Text := Txt;
end;
This changes the metaphor. Instead of indexing into the string as an array, we're treating it like a tape, with the pointer as the head, moving forward one character at a time, scanning from beginning to end, and changing the character under it when appropriate. No redundant calls to UniqueString, and no repeatedly calculating offsets, which means this can be a lot faster.
Be very careful when using pointers like this. The compiler's safety checks are there for a good reason, and using pointers steps outside of them. But sometimes, they can really help speed things up in your code. And again, profile before trying anything like this. Make sure that you know what's slowing things down, instead of just thinking you know. If it turns out to be something else that's running slow, don't do this; find a solution to the real problem instead.
Edit: Looks like I was wrong - UniqueString is not the problem. The actual bottleneck seems to be accessing the string by character. Given that my entire answer was irrelevent, I've completely replaced it.
If you use a PChar to avoid recalculating the string offset, while still updating the string via Txt[Idx], the method is much faster (5 seconds down to 0.5 seconds in my test of 1000 runs).
Here's my version:
procedure TForm1.btn1Click(Sender: TObject);
var
Idx: Integer;
Tag: Boolean;
p : PChar;
Txt : string;
begin
Tag := False;
Txt := Mem1.Text;
p := PChar(txt);
Dec(p);
For Idx := 0 to Length(Txt) - 1 Do
Begin
Inc(p);
If (not Tag and (p^ = '<')) Then begin
Tag := True;
Continue;
end
Else If (Tag and (p^ = '>')) Then
Begin
Tag := False;
Continue;
end;
If Tag Then Continue;
If (not (p^ in [#10, #13, #32])) Then begin
Txt[Idx] := '0';
end;
end;
mem2.Text := Txt;
end;
I did some profiling and came up with this solution.
A test for > #32 instead of [#10,#13,#32] gains some speed (thanks #DavidHeffernan).
A better logic in the loop also gives a bit extra speed.
Accessing the string exclusively with the help of a PChar is more effective.
procedure TransformHTML( var Txt : String);
var
IterCnt : Integer;
PTxt : PChar;
tag : Boolean;
begin
PTxt := PChar(Txt);
Dec(PTxt);
tag := false;
for IterCnt := 0 to Length(Txt)-1 do
begin
Inc(PTxt);
if (PTxt^ = '<') then
tag := true
else
if (PTxt^ = '>') then
tag := false
else
if (not tag) and (PTxt^ > #32) then
PTxt^ := '0';
end;
end;
This solution is about 30% more effective than Mason's solution and 2.5 times more effective than Blorgbeard's.
I would like to use goto in MySQL stored function.
How can I use?
Sample code is:
if (action = 'D') then
if (rowcount > 0) then
DELETE FROM datatable WHERE id = 2;
else
SET p=CONCAT('Can not delete',#b);
goto ret_label;
end if;
end if;
Label: ret_label;
return 0;
There are GOTO cases which can't be implemented in MySQL, like jumping backwards in code (and a good thing, too).
But for something like your example where you want to jump out of everything to a final series of statements, you can create a BEGIN / END block surrounding the code to jump out of:
aBlock:BEGIN
if (action = 'D') then
if (rowcount > 0) then
DELETE FROM datatable WHERE id = 2;
else
SET p=CONCAT('Can not delete',#b);
LEAVE aBlock;
end if;
end if;
END aBlock;
return 0;
Since your code is just some nested IFs, the construct is unnecessary in the given code. But it makes more sense for LOOP/WHILE/REPEAT to avoid multiple RETURN statements from inside a loop and to consolidate final processing (a little like TRY / FINALLY).
There is no GOTO in MySQL Stored Procs. You can refer to this post:
MySQL :: Re: Goto Statement
I want to assign a value to a variable when exception occurs.
exception
when excep1 then
var = true;
when excep2 then
var = true;
end;
I want to do something like, Is it possible?
exception
var = true;
when excep1 then
-- do something
when excep2 then
-- do something
end;
Re-raising as Odi suggested would definitely work. You get the same effect by doing things a little differently.
begin
var := true;
... your code that can cause exceptions...
var := false; --var set to false unless an exception was encountered
exception
when exception1 then
...
when exception2 then
...
end;
You could do this with a sub-block, first set the value and then re-raise the exception to handle it:
begin
begin
-- do something
exception
when others then
var = true;
raise; -- re-raise the current exception for further exception handling
end;
exception
when excep1 then
-- do something
when excep2 then
-- do something
end;
Another way is to put it in another procedure, e.g.:
declare
procedure common_exception_routine is
begin
var = true;
end common_exception_routine;
begin
...
exception
when excep1 then
common_exception_routine;
when excep2 then
common_exception_routine;
end;