I get an error unknown identifier 'start'
my code:
visit_table(table: ETABLE)
local
t_array: ARRAY[ARRAY[ELEMENT]]
b_header: BOOLEAN
row_index: INTEGER
do
t_array := table.t_array
b_header := table.b_header
table.content := "<table>"
row_index := 0
from t_array.start
until t_array.off
loop
table.content := table.content + "<tr>"
from t_array.item.start
until t_array.item.off
loop
if row_index = 0 and b_header = TRUE then
table.content := table.content + "<th>" + t_array.item.content + "</th>"
else
table.content := table.content + "<td>" + t_array.item.content + "</td>"
end
end
table.content := table.content + "</tr>"
row_index := row_index + 1
end
table.content := table.content + "</table>"
end
I just want to parse through the objects of the 2d array and wrap html tags around them.
Is there something wrong with my syntax?
The class ARRAY does not inherit TRAVERSABLE that provides features start, after, forth and item. Therefore, arrays cannot be traversed using these features. Instead, the traversal is usually done using item indexes that start from lower and finish at upper. So, in your code there would be two variables i and j (one for the inner loop and another for the outer loop) of type INTEGER and the loops like
from
j := t_array.lower
until
j > t_array.upper
loop
... t_array [j] ... -- Use item at index `j`.
j := j + 1 -- Advance to the next element of the array.
end
An alternative is to use an iteration form of the loop:
across
t_array as x
loop
... x.item ... -- Use current item of the array.
end
The latter approach is closer to the one used in your current code, so you may prefer it more. Note that, in this case there is no need to call start, off and forth, because this is done automatically.
Finally, it's possible to use your current code, but iterate over linear_reprentation. For that you would need 2 more local variables p and q of types LINEAR [ARRAY [ELEMENT]] and LINEAR [ELEMENT] respectively. The first one would be initialized with p := t_array.linear_representation and the outer loop would use p.start, p.after, p.item and p.forth. The second one would be initialized with q := p.item.linear_representation. This is the most cumbersome method and I'm listing it only for completeness.
Related
I have to script a pascal code that rations into calculation the frequency of a character's appearance in the code and displays it through the output mode
Input P2 changes:
Second Attempt at the coding phase
I tried revisioning the code.I added the output variable writeln('input array of characters'); & writeln('Number of Occurrences',k);, which should help me output how many times did the S character appear overall in the code, plus utilised the for & if commands to have the final values showcased based on the conditions, if the frequency is 1 then count in S, still getting errors, take a look at the Input P2 & Output P2
Input P1
function Count(t, s: String): Integer;
var
Offset, P: Integer;
begin
Result := 0;
Offset := 1;
P := PosEx(t, s, Offset);
while P > 0 do
begin
Inc(Result);
P := PosEx(t, s, P + 1);
end;
end;
Output P2
Target OS: Linux for x86-64
Compiling main.pas
main.pas(5,3) Error: Identifier not found "Result"
main.pas(7,8) Error: Identifier not found "PosEx"
main.pas(8,3) Error: Identifier not found "unsigned"
main.pas(8,12) Fatal: Syntax error, ";" expected but "identifier N" found
Fatal: Compilation aborted
Error: /usr/bin/ppcx64 returned an error exitcode
-------------------------------------------------------------------
Input P2
program p1
var S:string
i:integer
begin
writeln('input array of characters');
k:=O;
for i:=1 to length (S) do
if (S[i])='m') and (S[i+1]='a') then k:=k+1;
writeln('Number of Occurrences',k);
Readln;
end.
Output P2
Compiling main.pas
main.pas(2,1) Fatal: Syntax error, ";" expected but "VAR" found
Fatal: Compilation aborted
Error: /usr/bin/ppcx64 returned an error exitcode
The errors you see in the first block:
Identifier not found "Result"
Standard Pascal doesn't recognize the pseudovariable Result. In some Pascal implementations (like e.g. Delphi) it can be used to assign a value to the function result. The Pascal you are using needs to have the result of a function assigned to the name of the function. For example:
function Whatever(): integer;
begin
Whatever := 234;
end;
Identifier not found "PosEx"
Not all Pascal implementations include the PosEx() function. You need to use Pos() instead. But, the standard implementation of Pos() doesn't include the "search start position" that PosEx has. Therefore you need to ditch Pos() and do as you do in "Input P2", that is traverse the text character per character and count the occurances as you go.
Identifier not found "unsigned"
Seems you have removed that unknown identifier.
The error you see in the second block:
In Output P2 the error message should be clear. You are missing a semicolon where one is needed. Actually you are missing three of them.
You are also missing the line that reads user input: ReadLn(S);.
Finally, to calculate both upper and lower case characters you can use an extra string variable, say SU: string to which you assign SU := UpperCase(S) after reading user input, and then use that string to count the occurances.
I think this is more like what you want to do:
function Count(t, s: String): Integer;
var
Offset,Res, P: Integer;
begin
Res := 0
Offset := 1;
repeat
P := Pos(t, s, Offset);
if p>0 then
Inc(Res);
Offset := P+1
untl P = 0;
Count := Res;
end;
Now, if you don't have Pos, you can implement it:
Function Pos(const t,s:string; const Start:integer):Integer;
Var
LS, LT, {Length}
IxS, IxT, {Index)
R: Integer; {Result}
begin
R := 0;
{use only one of the two following lines of code}
{if your compiler has length}
LS := length(S); LT := Length(T);
{If it does not}
LS := Ord(s[0]); LT := Ord(T[0]);
if (LS <= LT) {if target is larger than search string, it's not there}
and (Start<=LT) and {same if starting position beyond size of S}
(Start+LT <-LS) then {same if search would go beyond size of S}
begin {Otherwise, start the search}
ixT := 1;
ixS := Start;
repeat
Inc(R); {or R:= R+1; if INC not available }
If (S[ixS] <> T[ixT]) then
R := 0 {they don't match, we're done}
else
begin {Move to next char}
Inc(ixS);
Inc(ixT);
end;
until (R=0) or (ixT>LT); {if search failed or end of target, done}
Pos := R;
end;
I am writing this code in Ada for a class where we have to teach ourselves the code. I understand heap sort, but the Ada syntax is really confusing me. I don't understand why I am getting a constraint error in this sort function.
Essentially we have to pass array "A" into this procedure, and it should organize it. I get the constraint error at siftDown(A(Start...A'Last));
Thank you in advance
Procedure sort_3(A : in out array_type) is
procedure swap(Left : in out Integer; Right : in out Integer) is
temp : Integer;
begin
temp := Left;
Left := Right;
Right := Temp;
end swap;
procedure siftDown(A : in out array_type) is
Count : Integer := 1;
root : Integer := Integer'Pos(A'First);
child : Integer := Integer'Pos(A'Last);
last : Integer := Integer'Pos(A'Last);
begin
while root * 2 + 1 <= last loop
child := root * 2 + 1;
if child + 1 <= last and then A(Integer'Val(child)) < A(Integer'Val(child + 1)) then
child := child + 1;
end if;
if A(Integer'Val(root)) < A(Integer'Val(child)) then
swap(A(Integer'Val(root)), A(Integer'Val(child)));
root := child;
else
exit;
end if;
end loop;
end siftDown;
procedure heapify(A : in out array_type) is
Count : Integer := 0;
First_Pos : Integer;
Last_Pos : Integer;
Start : Integer;
begin
First_Pos := A'First;
Last_Pos := A'Last;
Start := Integer'Val((Last_Pos - First_Pos + 1) / 2);
loop
siftDown(A(Start...A'Last));
if Start > Integer'First then
Start := Integer'Pred(Start);
else
exit;
end if;
end loop;
end heapify;
Last_Index : Integer := Integer'Last;
begin
heapify(A);
while Last_Index > Integer'First loop
swap(A(Last_Index), A(A'First));
Last_Index := Integer'Pred(Last_Index);
siftDown(A(A'First..Last_Index));
end loop;
end sort_3;
You have a syntax error in the code - an extra dot in A(Start...A'Last).
The syntax A(Start..A'Last) means a slice, part of array from Start to the last element. The Constraint_Error means that Start not in array bounds. Try to add
Ada.Text_IO.Put_Line (Start'Image);
before that line and you will see Start values and when it became out of the A'Range.
Your code has some references to Integer'First and Integer'Last, which are huge values that have nothing to do with the array A and its values. I'm pretty sure you should use A'First and A'Last instead.
Also a note on style: Using the same identifier, "A", for the parameter of the local (inner, nested) procedures as for the parameter "A" of the containing (outer) procedure, when these arrays can be different, invites confusion and errors. Better to use different identifiers.
I have a array of Nodes:
type NodeArray is array (Positive range 1 .. 5) of XNode;
The node has some data and an integer ID but thats not important right now.
The way I undestand it is that array'First (excuse the abuse of notation) always points or references the first item in a range or array, not the integer of the range type.
My question is why I always get 1 instead of the first entry in my array.
If you need to see more code I can provide it, I just thought I'd keep my example simple and short.
Your
type NodeArray is array (Positive range 1 .. 5) of XNode;
defines a constrained array type (ALRM 3.6(5)), whose first index will always be 1.
If you want to use one type to create array objects with different index ranges, you need an unconstrained array type (ALRM 3.6(3)) with bounds like Positive range <> (note 1, once you’ve created such an object, its bounds are fixed; note 2, instead of Positive you can use any scalar appropriate to the problem).
with Ada.Text_IO; use Ada.Text_IO;
procedure Zython is
type Unconstrained_Node_Array is array (Positive range <>) of Float;
subtype Constrained_Node_Array is Unconstrained_Node_Array (1 .. 5);
U : Unconstrained_Node_Array (42 .. 44); -- must include the index range
C : Constrained_Node_Array; -- the index range is 1 .. 5
begin
for J in U'Range loop
U (J) := Float (J) * 2.0;
end loop;
Put_Line ("U'First: "
& Positive'Image (U'First)
& ", U (U'First): "
& Float'Image (U (U'First)));
for J in C'Range loop
C (J) := Float (J) * 2.0;
end loop;
Put_Line ("C'First: "
& Positive'Image (C'First)
& ", C (C'First): "
& Float'Image (C (C'First)));
end Zython;
So I have been given an assignment to read in a file put the numbers into two matrices, multiply the matrices, and finally put the output into a .txt file.
I have never used Ada before and I figured it would be a good challenge. I am stuck in trying to determine the bounds for the two separate arrays.
This is what I currently have:
currentSpread := I;
g := Ada.Numerics.Generic_Complex_Elementary_Functions.Sqrt(I);
while J < g loop
if(I mod J = 0) THEN
if(currentSpread > ((I/J - J)/2)) THEN
currentSpread := ((I/J - J)/2);
arrayBounds := J;
end if;
end if;
J := J + 1;
end loop;
The problem I am having is with the sqrt function. I want to find the factors for the best bounds of the matrix multiplication and this was the only way that I thought to implement it.
The error I am getting is:
invalid prefix in selected component "Ada.Numerics.Generic_Complex_Elementary_Functions"
Thanks a lot for any help.
--Update
Full Code as requested:
with Ada.Text_IO;use Ada.Text_IO;
with Ada.Integer_Text_IO;
with Ada.Numerics.Generic_Complex_Elementary_Functions;
with Ada.Numerics.Generic_Elementary_Functions;
with Ada.Numerics.Complex_Elementary_Functions;
with Ada.Numerics.Generic_Complex_Types;
procedure Main is
dataFile : File_Type;
resultFile : File_Type;
value : Integer;
I : Integer := 0;
J : Integer;
currentSpread : Integer;
arrayBounds : Integer;
g : Integer;
begin
Ada.Text_IO.Open(File => dataFile, Mode => Ada.Text_IO.In_File, Name =>"C:\Users\Jeffrey\Desktop\data.txt");
while not End_Of_File(dataFile) loop
Ada.Integer_Text_IO.Get(File => dataFile, Item => value);
Ada.Integer_Text_IO.Put(Item => value);
Ada.Text_IO.New_Line;
I := I + 1;
end loop;
Ada.Integer_Text_IO.Put(I);
I := I/2;
J := 1;
currentSpread := I;
g := Ada.Numerics.Generic_Complex_Elementary_Functions.Sqrt(I);
while J < g loop
if(I mod J = 0) THEN
if(currentSpread > ((I/J - J)/2)) THEN
currentSpread := ((I/J - J)/2);
arrayBounds := J;
end if;
end if;
J := J + 1;
end loop;
declare
type newArray is array(Integer range <>, Integer range<>) of Integer;
X : Integer := J;
Y : Integer := I/J;
Arr1 : newArray(1..Y, 1..X);
Arr2 : newArray(1..X, 1..Y);
finAnswer : newArray(1..X, 1..X);
begin
for z in 1 .. X loop
for k in 1 .. Y loop
Ada.Integer_Text_IO.Get(File => dataFile, Item => value);
Arr1(z, k) := value;
end loop;
end loop;
for z in 1 .. Y loop
for k in 1 .. X loop
Ada.Integer_Text_IO.Get(File => dataFile, Item => value);
Arr2(z, k) := value;
end loop;
end loop;
for l in 1 .. X loop
for m in 1 .. Y loop
for n in 1 .. X loop
finAnswer(l, n) := finAnswer(l, n) + Arr1(l, n)* Arr2(n, m);
end loop;
end loop;
end loop;
end;
Ada.Text_IO.Close(File => dataFile);
end Main;
I am using the square root exclusively to figure out the factors of a number nothing else. How I have it set up now is it will go up to the square root and then it will take the smallest spread of the factors. I do not care about rounding errors or anything else if it isn't a perfect square it can round either way.
Thanks.
Generic_Complex_Elementary_Functions is a generic package. It cannot be used directly. That is why the compiler gives you an error on this line:
Ada.Numerics.Generic_Complex_Elementary_Functions.Sqrt(I);
To use it, you have to instantiate the generic Generic_Complex_Types with the floating-point type you want to use, and then instantiate Generic_Complex_Elementary_Functions with an instance of Generic_Complex_Types. Fortunately, you don't have to go through all that if you're willing to use the built-in type Float; the language provides Ada.Numerics.Complex_Elementary_Functions for you, that uses Float as the floating-point type, or Ada.Numerics.Long_Complex_Elementary_Functions that uses Long_Float if your compiler vendors support it.
However, I don't think you want to use Complex anything. That deals with complex numbers, and I doubt that you want to use those. Use Ada.Numerics.Elementary_Functions (or Long_Elementary_Functions), which deal with real numbers.
Finally, even this isn't going to work:
Ada.Numerics.Elementary_Functions.Sqrt(I)
if I is an integer, because the argument type needs to be a Float. You'll have to use a type conversion.
Ada.Numerics.Elementary_Functions.Sqrt(Float(I))
So I created a proc that returns a value. (sqrt analog that is correct for numbers from (2.1) and up). I can evaluate it for any given number but I cannot plot it. Why and how to fix it?
code (converted to 1-d math input):
>
restart:
with(plottools):
val := 248;
sqr := proc (sqrtFrom, iterations) answer := 0; ampl := 0; number := sqrtFrom; for k to iterations do answer := 10*answer; number := sqrtFrom*10^ampl; for i from 0 while i < number do answer := answer+1; i := answer^2 end do; answer := answer-1; difr := -1; while difr < 0 do ampl := ampl+1; difr := sqrtFrom*10^ampl-100*answer^2 end do end do; return evalf(answer/10^(iterations-1)) end proc;
>
evalf(sqrt(val));
sqr(val, 10);
plot(sqr(x, 10), x = 3 .. 5);
>
You need eval quotes. Try
plot('sqr'(x,10), x = 3..5 );
The error you get is because sqr is being called prematurely with x as an argument, and it can't do that.
Alternatively, you can modify sqr itself to return unevaluated if it gets non-numeric arguments (which is how sqrt works).