Is there any problem?

[7vinbaby]

Here is my code and i got some problems.

Code: [Select]

var
   no:array[1..30] of string;
begin
for x:=1 to 30 do
  no[x]:'';
  {Then i enter the value of arrayX.One is null and other is not}
  y:=0;
  while y<30 do
  begin
  if no<>''
  then
     begin
     y:=y+1;
     no[y]:=no[y];
     end;
   end;
end.

i use trace into and found my program is stuck in the selection of ' if no<>'' ' ,  could someone help me please?

[Thaddy]

 

Code: Pascal  [Select][+][-]

1. if no[y]<>'' //not  if no<>''

But that will crash too since there is no no[0];
You have to revise your code accordingly.... like:

Code: Pascal  [Select][+][-]

1. program untitled;
2. var
3.    no:array[1..30] of string;
4.    X,y:integer;
5. begin
6. for x:=1 to 30 do
7.   no[x]:='';
8.   {Then i enter the value of arrayX.One is null and other is not}
9.   y:=1;
10.   while y<31 do
11.   begin
12.   if no[y]<>''
13.   then
14.      begin
15.      no[y]:=no[y];
16.      y:=y+1;
17.      end;
18.    end;
19. end.

[7vinbaby]

 

Code: Pascal  [Select][+][-]

1. if no[y]<>'' //not  if no<>''

But that will crash too since there is no no[0];
You have to revise your code accordingly.... like:

Code: Pascal  [Select][+][-]

1. program untitled;
2. var
3.    no:array[1..30] of string;
4.    X,y:integer;
5. begin
6. for x:=1 to 30 do
7.   no[x]:='';
8.   {Then i enter the value of arrayX.One is null and other is not}
9.   y:=1;
10.   while y<30 do
11.   begin
12.   if no[y]<>''
13.   then
14.      begin
15.      no[y]:=no[y];
16.      y:=y+1;
17.      end;
18.    end;
19. end.

Yes,thank you .I miss that point.

[wp]

Here is my code and i got some problems.

Which problems? We cannot read your mind.

Code: [Select]

for x:=1 to 30 do
  no[x]:'';
  {Then i enter the value of arrayX.One is null and other is not}
  y:=0;
...

The indentation tells me that the for loop should contain not only the no[ x] := '' line. If the for loop should contain more lines then use "begin" after the for's "do". If not correct your indentation. Proper indentation is one of the most important time savers for a programmer!

Code: [Select]

  no[x]:'';

This is not a valid statement. You probably mean: no[ x] := ''

Code: [Select]

  if no<>''
  then

Another invalid statement. "no" is an array, and you can only access it by element. You probably mean "no[ x]", or "no[ y]"

Code: [Select]

     no[y]:=no[y];


This is pure nonsense: You assign a variable to itself and do not change anything.

[molly]

Perfectly valid code

Code: [Select]

y:=y+1;
no[y]:=no[y];
Simply doesn't make any sense

Perhaps You must be thinking of something similar like:

Code: [Select]

y:=y+1;
no[y]:=no[y+1];


[Thaddy]

Yes,thank you .I miss that point.

But how can you miss that?
The compiler explains to you what mistake you made....

[7vinbaby]

Code: [Select]

y:=y+1;
no[y]:=no[y];


actually i want to update the record in the array so if there is null space,i do not put it into the array.
However i can't have more idea about this

[molly]

actually i want to update the record in the array so if there is null space,i do not put it into the array.
However i can't have more idea about this

Ah ok. You would like to clean up your array from 'empty' answers ? Did i understood that correctly ?

In that case, a couple of questions arises
- Why put empty answers into the array to begin with ?
- Why use a static array ?

But, in order to satisfy your curiosity which follows your lead:

Code: [Select]

procedure CleanArray;
var
  i, j : Integer;
begin
  i := low(no);
  for j := low(no) to High(no) do
  begin
    if (no[j] <> '') then
    begin
      no[i] := no[j];
      If i <> j then no[j] := '';
      inc(i);
    end;
  end;
  WriteLn('Number of non empty items in array = ', Pred(i));
end;

Note though, that the above code is _not_ the way to go as it is too error-prone. I'm showing it in order to let you see why.

[Handoko]

How about this one:

Code: Pascal  [Select][+][-]

1. program UpdateArrayDataIfNotEmpty;
2.  
3. var
4.   MyArray: array[1..30] of string;
5.   i, j   : integer;
6.   Found  : boolean;
7.  
8. begin
9.  
10.   // Initial the array with empty string
11.   for i := Low(MyArray) to High(MyArray) do
12.     MyArray[i] := '';
13.  
14.   // Store data into MyData but skip non empty array
15.   i := 1;
16.   while i<30 do begin // Store 30 items into the array
17.     j := Low(MyArray);
18.     Found := False;
19.     repeat // to find an empty space on the position j
20.       if MyData[j] := '' then
21.         Found := True
22.       else
23.         inc(j);    
24.     until Found or (j>=High(MyData));  
25.     if Found then MyData[j] := 'Data#'+IntToStr(j);
26.     inc(i);
27.   end;
28.  
29.   // Show it
30.   WriteLn('Stored data in the array:');
31.   for i := Low(MyArray) to High(MyArray) do
32.     WriteLn(MyArray[i]);
33.  
34. end.

[Thaddy]

@Handoko your code is wrong:

Code: Pascal  [Select][+][-]

1.   while i<30 do begin // Store 30 items into the array
2. // Nope it stores 29 elements. I corrected that already in my example
3. // he starts at one...
4.  

[Handoko]

Oh, my mistake. 

I usually use <= or >= but why I forgot to use it. It should be:

Code: Pascal  [Select][+][-]

1.   while i<=30 do begin

Thanks Thaddy for that correction.