I was trying to make a little test program to count how many times letter 'a' appears in an text without using string type:
program PascalTest;
uses WinCrt;
var
a:integer;
ch:char;
begin
a:=0;
writeln('Input text: ');
read(ch);
while ch <>'.' do // '.' marking the end of text ("eoln" could've been used instead)//
begin
case ch of
'A','a':a:=a+1;
end;
read(ch);
end;
writeln(a);
readln;
readln; //forcing output window to stay open//
end.
I noticed that if I dont add another 'readln' statement at the end , the output window will not show results (it will flash in an instant if u will).This is happening only with this program.All the other ones require only one 'readln' so the window can stay open. Can somebody explain to me why is another 'readln' statement needed in this case?
The first readln ends the while loop. Note that you can enter many '.' without loop exit. Further note the writeln(a) is delayed until you press <Enter>. The second readln allows you to view the output.
Make a test: Uncomment both readln and see if you can end the program by entering a '.'.
WinCrt is a consoleless CRT to use in combination with unit GRAPH.
Use unit Crt for normal console output.
Related
I want a text file to show contents in memo1 once I have selected 2 checkboxes.
How would I do this?
I tried the code below but I can't seem to get it right.
if CheckBox1.Checked and CheckBox2.Checked then
begin
memo1.lines.LoadFromFile('files\RS.txt');
end;
I also want to be able to select the checkboxes individually Like:
(pointing this out in case combining them prevents checking them individually)
Checkbox1:
procedure TForm1.CheckBox1Change(Sender: TObject);
begin
memo1.lines.LoadFromFile('files\R.txt');
end;
Checkbox2:
procedure TForm1.CheckBox2Change(Sender: TObject);
begin
memo1.lines.LoadFromFile('files\S.txt');
end;
Any suggestions/Improvements will be appreciated.
Running Lazarus IDE v1.6.4
Windows 10 x64
I'm assuming your objective is to generate a filename which depends on the
particular combination of the boolean states of the two checkboxes -
see example code below. The point of doing this is that it helps separate
the definition of what you want the file name to be from what you want to do
with it.
procedure TForm1.Button1Click(Sender: TObject);
begin
Memo1.Lines.LoadFromFile(GetFileName);
end;
function TForm1.GetFileName: String;
begin
// Return empty string if neither checkbox is checked
Result := '';
if Checkbox1.Checked and Checkbox2.Checked then
Result := 'files\RS.txt'
else // if we reach here only one of the checkboxes, or neither, is checked
if Checkbox1.Checked then
Result := 'files\R.txt'
else
if Checkbox2.Checked then
Result := 'files\S.txt'
end;
I've assigned an empty string to the Result of the function at the outset to ensure that the Result is always defined.
Important You'll notice that the above does not use the Change events of the Checkboxes. The reason is that you may not get the result you need (or are expecting) if the Change events are never triggered - for example if one CheckBox is set to Checked in the IDE but the other isn't, and you want to get the right file name regardless of whether the user has actually clicked either one of them.
As far as I understood you want the following behaviour:
There are two check boxes
There is one memo field
Depending on the state of the two check boxes the text in the memo field shall change
If this understanding is correct:
I typically don't use Pascal but your problem seems to be independent of the programming language used. I would do it like this:
The two procedures TForm1.CheckBox1Change and TForm1.CheckBox2Change are called whenever the corresponding check box'es state changes.
I would write a third procedure and call this third procedure from both procedures. I would do nothing else than calling this third procedure in the other two procedures.
In the third procedure I would evaluate what to do - depending on the state of both check boxes.
A separate checkboxchange proocedure per event is automatically generated by the designer if you double click the event. However that is not a rigid decision.
If you have the initial codefragment in e.g. checkbox1change, you can simply point the onchange of checkbox2 to that existing checkbox1change by using the dropdown of the onchange of checkbox2
create or replace procedure HelloWorld(s varchar)
as
begin
dbms_output.put_line(s);
end;
-------- click execute button now
exec HelloWorld('Hello');
The codes above is from the school slide. The first code is shown as 'procedure created' which means good to go. When I execute it by using 'exec HelloWorld(‘Hello’);', it shows errors. May I ask some of question regarding this code please?
1) Why it does not work when I execute it?
2) I know that 's' is a parameter, and 'varchar' is the datatype for 's'. However, the code requires that print 's'. As I can see, there is nothing to assigned on 's'. Then, how can the code runs the value of 's' in 'dbms_output.put_line(s);'?
3)Can anybody just explain what is the basic function for each single word?
I need the user to enter only real numbers when prompted. An error message should be displayed and program should stop in case the user enters a character or any other symbol. How can i do this in fortran 77.
I assumed, you probably want to have more tries, because what you have in your question does the compiler does automatically.
You can use the IOSTAT= or ERR= specifiers.
INTEGER IE
DO I = 1, MAX
READ(*,*,IOSTAT=IE) X
IF (IE.eq.0) GOTO 10
PRINT *,"Wrong input, try again."
END DO
10 CONTINUE
or
GOTO 10
20 PRINT *,"Wrong input, try again."
10 READ(*,*,ERR=20) X
improving the user interface a little, i like to read a string, then do the error check on an internal read:
character insting*80
ie=1
do while(ie.ne.0)
read(*,'(a)')instring
if(instring(1:1).eq.'q')stop
read(instring,*,iostat=ie)x
if(ie.ne.0)then
write(*,*)'invalid input ',trim(instring),' is not a real number'
endif
enddo
(note trim is not f77 btw, but its easy enough to replicate if needed)
Note, with some effort you can handle the pathalogic cases. A leading '/' or ',' throws no error but leaves the value of x unchanged (likely system/compiler dependent however!), so you can do something like this:
x=-999999.
read(instring,*,iostat=ie)x
if(ie.eq.0.and.x.eq.-999999.)then
.. code to handle error..
endif
You could alternately use index to look for the bad characters. On my system a decimal . by itself is taken as zero. That gets a bit cumbersome to handle, but it can be done by parsing instring
I have a string 'sSQL' that contains a very long tsql statement. I need to check what its value is while debugging. I usually just use ?sSQL in the immediate window but this is truncating the first half and only giving me the end half.
So is there an alternative way to see the full value using the vb6 sp5 dev environment?
For debugging, Clipboard.Clear: Clipboard.SetText ssql then paste into notepad.
While execution is paused on the breakpoint you could type in the immediate window:
Debug.Print(sSql)
;-)
One way is to use write the string out to a file. You can do this in a single line in the immediate window by using Line continuations, e.g.:
Open "C:\SQL.TXT" For Append As #1: Write #1,sSQL : Close #1
Note: You'll need to change C:\SQL.Txt to a path that you can write to depending on your OS.
If it's that long, save it to a text file. Have a debug method:
sub SaveStringToDebugFile(s as string)
...
end sub
and then call it from the immediate window:
SaveStringToDebugFile sSQL
Erm, the immediate window doesn't truncate (except at 200 lines of 1023 characters). Have you just tried pressing the home key or scrolling left?
Check the length of the "long" string using the Immediate:
?len(sSQL)
4221
then knowing the size you can start getting chunks of string using Mid function:
?Mid(sSQL, 1, 500)
?Mid(sSQL, 500, 1000)
?Mid(sSQL, 1000, 1500)
Here is my dilemma:
I'm very new to programming in VHDL, and I'm currently working on an independent study project for a university class. I've made some descent headway, but I've run into an issue I haven't been able to solve.
What I'm trying to do is to display a "register" (or registers) on an LCD monitor and have it update periodically. For the time being, these values will always be integer numbers.
I have code written which displays numbers properly on the screen if that value is passed as a variable that is never altered or as a hard-coded value. However, I want to update a variable by adding to it, then pass that to my function and display it.
Essentially what I'm trying to do is this:
Every 'x' clock ticks, increment a register's value, pass that to my update_screen function which returns a new screen, and then display that further below. However, once I increment or change through reassignment (doesn't seem to matter if it is variable or a signal), all I see is '0' on the screen.
So... The following code properly updates my display unless I uncomment the commented lines. At that point, it just shows '0'.
--currentRegVal := currentRegVal + 1;
--screenVal <= 25;
-- screen holds the values for the current screen
-- The second argument is the row on the screen to be updated
-- The third argument is the value to display there
screen := update_screen(screen, 1, currentRegVal);
screen := update_screen(screen, 0, screenVal + 25);
The problem seems to be stemming from the integer'image attribute (or more accurately, my understanding of it). When I pass in a hardcoded value or a variable that hasn't been altered, it returns what I expect. However, as soon as I modified the variable/signal in ANY way it seems to return the string "0".
Below is my update_screen function:
function update_screen(screen: screenData; reg, regVal: integer) return screenData is
-- A function may declare local variables. These do not retain their values between successive calls,
-- but are re-initialised each time. Array-type parameters may be unconstrained:
constant screenWidth: integer := screen'length(2);
constant strRegVal: string := integer'image(regVal);
constant strRegLen: integer := strRegVal'length;
variable newScreen: screenData := screen;
begin
for dex in 1 to screenWidth loop
if dex <= strRegLen then
newScreen(reg, dex-1) := strRegVal(dex);
else
newScreen(reg, dex-1) := ' ';
end if;
-- The next two ifs were my attempt to figure out what
-- was going on...
--The value itself never seems to be 0... the screen is not all 5's
if regVal = 0 then
newScreen := (others => (others => '5'));
end if;
-- But the string value is "0" if the variable/signal is ever modified...
-- 'd' shows up in the designated row.
if strRegVal = "0" then
newScreen(reg*3, 1) := 'd';
end if;
end loop;
return newScreen;
end update_screen;
A couple important points (added 2011-07-26):
I'm using the Quartus II free (web) edition to design/compile my project.
The code which is updating the variables is in a process.
At the time of the original posting, the only steps I had taken were to compile my code and program an Altera DE2 FPGA board with the result (I wasn't sure how to perform any kind of simulations).
Thanks in advance for any help and advice. Also, as I said, I'm new to VHDL programming, so if there is a much better way to do something I'm doing here, please let me know. I would also greatly appreciate useful links to any resources about the language itself.
Update (2011-07-26):
I downloaded GHDL as Martin Thompson suggested, but I have not actually used it yet because I'm not sure how to go about doing so with my current Quartus II project (or if I even can). I'll have to do some reading before it is useful to me. However, yesterday I managed to install ModelSim-Altera which works directly with Quartus II and allowed me to perform some simulation.
I did my best to set up some waveforms that would allow me to test, and I was at least able to examine the execution of the code which I believed to be failing. However, during simulation, I've verified in multiple ways that the "screen" object does contain the value I want it to contain after the *screen_update* function runs. When running on the Altera DE2, however, it still fails.
Note: I did verify that the screen actually does update by directly setting the value of a particular element on the screen to different values depending on whether or not the currentRegVal is even or odd.
I'll plan on posting some code tomorrow, but for now:
What reasons are there that simulation would provide different results? My guess is something to due with timing, but it is really just a guess. If I am correct, how can I go about trying to resolve the issue?
I guess the problem is related to the fact that you declared strRegVal as a constant. I think it should better be a variable, e.g. something like this might work:
function update_screen(screen: screenData; reg, regVal: integer) return screenData is
...
variable strRegVal: string;
variable strRegLen: integer;
...
begin
strRegVal := integer'image(regVal);
strRegLen := strRegVal'length;
...
end update_screen;
Assuming this code is in a process:
screenVal <= 25;
-... snip...
screen := update_screen(screen, 0, screenVal + 25);
screenVal won't have updated to a new value yet (unless some time passes - a wait statement between the write and the read)