I'm confused because when I define a type from 1 to maxint in Pascal and I make the choice "0" which should return back to the repeat loop. Here is my code:
program Tanken;
type
tZahl = 1..maxint;
var
tag1 : tZahl;
wahl : tZahl;
liter,
p : real;
BEGIN
repeat
write ('Bitte Tag eingeben 1=Mon 2=Die 3=Mit 4=Don 5=Fre 6=Sam 7=Son: ');
readln (tag1);
writeln(tag1);
until tag1 <= 7;
....
end
This is how my constant, type and variable looks. Si I define tag1 as tZahl which should be from 1 to maxint but how ever when I run this at the first repeat loop when I type "0" it is accepted. I found this a bit confusing any ideas?
To force type range checking at runtime you need to explicitly tell the compiler to with most used compilers by adding {$R+} to the top of the program.
However this will only throw a runtime error, which is not the input validation that you want. You will really need to program input validation yourself. E.g. by reading a string, and then converting it to a number using the VAL() procedure and checking the code argument for errors.
Related
New to elm here, and at first it's driving me absolutely crazy not knowing the ins and outs of this picky language (even after reading a sh**load about it because it's just so different and finicky... I guess that's the nature of a functional lang) so when you try doing a simple thing it's like pulling hair at first.
I am getting the following error:
The right side of (==) is causing a type mismatch.
29| get 0 arrayOfValues == 'X'
^^^
(==) is expecting the right side to be a:
Maybe Char
But the right side is:
Char
Hint: With operators like (==) I always check the left side first. If it seems
fine, I assume it is correct and check the right side. So the problem may be in
how the left and right arguments interact.
Test:
it "blah blah blah" <|
let
someArray =
[ 'P', ' ' ]
in
expect (MyModule.doSomething someArray 'P') to equal 1
MyModule
doSomething : List Char -> Char -> Int
doSomething arrayOfValues symbol =
let
grid =
fromList arrayOfValues
found =
get 0 arrayOfValues == symbol
in
if found then
1
else
0
Now I'm assuming but not sure, that it's getting Nothing or something when trying to pull the first value out of my array but not sure. Maybe Char I assume is returning Nothing? donno, probably have other issues going on with it too.
I'd like to get the code above working, then refactor..I'm sure there's probably a more elegant way to code what I've coded above but first thing's first, fixing this error and understanding it better with the existing code. The error message while nice isn't that obvious to me as to how and what to handle. I have assumptions but not fully sure how to handle the behavior here of whatever is causing the issue.
Unique feature of the elm is certainty. Any variable (which is not of type maybe) will have a value of the defined type for sure.
But when it comes to array or list, it becomes uncertain if the array has an element on index "i". There may be an element and there may not be.
Hence elm has concept of Maybe,
so conceptually
Maybe String = [ Just "string_value" | Nothing ]
the alias for the Array.get is
get : Int -> Array a -> Maybe a
it takes
Int - index and
Array a - array of data type of array element
as parameters and returns
Maybe a - again a is the data type of array element
consider an example
array =
fromList ["one", "two"]
val1 =
get 0 array -- will return 'Just "one"'
val2 =
get 3 array -- will return 'Nothing', since the element does not exists
this way you will always have to handle both the situations, when you have a value and when you don't
case val1 of
Nothing ->
-- Raise some error message
Just val ->
-- `val` is the actual element/value found
and if you always need a default value, you can use
Maybe.withDefault "default_string" val1
this will always return a string value and will return "default_string" when the value is nothing otherwise the actual found value
I'm having a problem running my script. I can't for the life of me figure out what the illegal character is.
I have tried putting the string concatenation on separate lines, and I get the same error. I have tried using OneDate and TwoDate instead of Date_1 and Date_2, also to no avail. I have updated AHK, which didn't solve it.
I should note that I am using both MonthCal and DateTime Gui control to get these dates, then formatting them with FormatTime. Another error I have noticed, which may provide a clue, is that no matter what dates I pick in the date controls, I get 2017-Sep-01 as the output. It's possible that no values are coming through from the controls, and the FormatTime function is using today's date because the variables it's attempting to work on are blank / don't exist.
Other than than, generally I like to be more descriptive in my questions, but in this case, I think all I can say is: "Help?"
When you use the expression assignment method := you shouldn't use %. Instead you should write Output := Output Date_1 "_to_" Date_2. When you do use % with expression assignment Autohotkey dereferences the variable and tries to treat OtherDescription--2017... as a variable name and - is not a legal character for an Autohotkey variable.
The following example will help make it more clear:
astring := "some text"
output = a
Output := %Output%STRING
MsgBox % Output
The MsgBox will show "some text". This happens because Autohotkey dereferences %Output% to "a" and then assigns to it the value of astring variable (it concatenates "a" and "STRING" and then looks for a variable called astring).
This should be a simple question on JasperReports. I'm trying to do a simple counter over the whole report that should increment based on a condition. However, whatever I try, it seems like the counter variable is always being incremented, regardless of the variable expression. My variable's definition properties are below:
Class: Integer
Calculation: Count
Reset type: Report
Increment type: None
Variable Expression: $F{on_target}.doubleValue() >= 0.0
Initial Value: Integer.valueOf(0)
I have a total of 23 rows in the data set, and based on the criteria, the counter should eventually equal 18. I have the variable outputting in the Summary band, with Evaluation Time to Now. However, regardless of the evaluation time, and even setting the Variable Expression to Boolean.valueOf(true == false), the variable's value always ends up as 23.
What simple little thing am I forgetting?
I think I've got it. This makes vaguely no sense, but... (mind you, this is my first time working with Jasper Variables, so it was trial and error).
The Variable Expression isn't quite a Boolean, where a counter type variable isn't incremented if the expression is false, like you'd think. The variable is incremented if there is any value evaluated in the expression. Thus, for me, what ended up working is below:
$F{on_target} >= 0 ? 1 : null
Note the usage of null if the expression should be false.
It makes vague, twisted sense. But is in no way intuitive. Oh well, so it goes...
or in other words:
When you are using the Calculation:Count function of a Jasper-defined Variable you want the Variable Expression to:
resolve to non-null value to increment the counter
resolve to a null value if you do not want to increment the counter
That's why the test listed above works
As well as the setting the variable expression to:
$F{on_target} >= 0 ? 1 : null
Try also setting the initialValueExpression of the variable to 0.
This worked for me:
$F{on_target} >= 0 ? 1 : BigDecimal.ZERO
No initial variable value necessary.
Just as a forward, I am a complete beginner when it comes to Fortran. I've spent quite awhile looking at the other questions on SO, but I couldn't identify a similar question to this, so please forgive me if my solution is either obvious, or already been answered :)
I'm attempting to learn how to correctly implement a self-written Fortran DLL in a VB.net application. I've been able to have VB recognize the DLL, and execute the function without any errors. The error comes rather as expected output compared to actual output.
My Fortran DLL function reads as follows:
function ex(i)
integer*4 i
ex=i+1
return
end
A very simple function that increments the passed parameter by one and returns the value. (I think). The VB Application has the following code.
<DllImport("ex.dll")> _
Public Shared Function ex(ByRef val As Integer) As Integer
End Function
Private Sub btn_Fortran_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btn_Fortran.Click
Console.WriteLine(ex(1))
End Sub
So, I'm passing the ex function the integer value 1. So I would expect the value 2 to be written to the console. Instead, I get the value "1073741824" Not exactly equal. Any ideas where I'm obviously falling short?
Learning a language in a mixed language content is "a hard row to hoe". Note that value you obtained is 2**30.
In the fortran portion, you should also declare the return value of the function: "integer*4 function ex (i)" is the old fashioned way. You are probably getting ex as a real through implicit typing. It is a very good idea to include "implicit none" in all of your programs and procedures to prevent implicit typing. Many compilers include an option for the same purpose.
Late edit:
Here is a program that demonstrates what was happening by showing what value is obtained when the bit-pattern real value 2.0 is interpreted as an integer. First the program equates a real and an integer. In this case the compiler "knows" about the types and converts the value. In the second case the raw bit pattern is transferred without being converted.
program test_tc
real :: my_real
integer :: my_int
my_real = 2.0
my_int = my_real
write (*, *) my_int
my_int = transfer ( my_real, my_int )
write (*, *) my_int
end program test_tc
Output is:
2
1073741824
It appears that I was nearly on the right track, but the way in which I declared 'i' made some weird things happen. When using the following convention of
integer*4 :: ex, i
The function returns the correct value. So, my function looks like this
function ex(i)
integer*4 :: ex, i
ex=i+1
return
end function
Thanks both of you for the help. I upvoted both of you for simply opening my eyes to some aspect of the language I didn't fully understand beforehand.
I am wondering if anyone could tell me any special meaning of the dot (.) in Informix regarding expressions and etc.
For example in stored procedures I see it used with integers, decimals and chars and one thing that is bugging me quite a lot is this:
if value = '.' then
//do something
end if
The above expression validates to true when value is of type numeric (5,1) and it is equal to 0.0
I have tried looking around and I can't find information on how a dot is treated but it seems " 0.0 = '.' " validates to true.
Can you show the data types and a working stored procedure that illustrates the problem?
There isn't supposed to be any special meaning to dot in that context. It is a string, and no numeric value should be equal to it; if the number is converted to a string, there will be either nothing (for NULL) or at least one digit, neither of which is the same as the string '.', and if the string '.' is converted to a number, that conversion should fail (arguably when the procedure is created, certainly at runtime).
One thing that puzzles me is that the syntax you are showing is not SPL syntax. SPL does not use 'end if', though I4GL does. Indeed, SPL (stored procedure language) only uses END in conjunction with a matching BEGIN.
It appears that my memory is failing and that I should not try reading manuals just before midnight.
It also appears that this code does what I would not expect...
+ set debug file to "/tmp/x1";
SET DEBUG FILE TO: Rows processed = 0
+ drop procedure so2139024();
DROP PROCEDURE: Rows processed = 0
+ create procedure so2139024() returning int as rv;
define value numeric(5,1);
define rv integer;
trace on;
let rv = 0;
let value = 0.0;
if value = '.' then
let rv = 1;
end if;
return rv;
end procedure;
CREATE PROCEDURE: Rows processed = 0
+ execute procedure so2139024();
1
EXECUTE PROCEDURE: Rows processed = 1
So, for some reason, the comparison is working; the value zero compares equal to dot. This was tested on MacOS X 10.6.2 with IBM Informix Dynamic Server 11.50.FC6 (and SQLCMD 86.04, built with CSDK 3.50.FC4, but running with 3.50.FC6).
The debug file contains:
trace on
expression:(= value, ".")
evaluates to t
let rv = 1
expression:rv
evaluates to 1
procedure so2139024 returns 1
iteration of cursory procedure so2139024
A priori, this should be reported via IBM/Informix Tech Support. I think it is most likely a bug of some sort, but I don't know how it is coming up with the answer. I will check through back-door channels too.
Back-door channels show that the likely problem is that the function deccvasc() in the ESQL/C library (also used internally by the server) is mishandling the string '.'.
The ESQL/C test code here shows that:
#include <stdio.h>
#include "dumpesql.h"
int main(void)
{
dec_t d;
int rc = deccvasc(".", 1, &d);
printf("rc = %d\n", rc);
dump_decimal(stdout, "Decimal", &d);
return(0);
}
The dump_decimal() function is non-standard, but prints information from the decimal structure. The output is:
rc = 0
DECIMAL: Decimal -- address 0x7FFF5FBFF090
E: -64, S = 1 (+), N = 0, M = value is ZERO
Consequently, the server is (mistakenly) accepting '.' as a valid representation of zero, rather than getting an error reported. For the time being, you will have to edit the stored procedure to make more sense - it is not clear what the test was supposed to achieve, but it clearly isn't written correctly. (That is not denying that there is also a bug in the server.) Please report this to IBM/Informix Technical Support.