Hello I want to use Shannon-Fano algorithm in Delphi. My tables for string that "ABCDE" like this:
This method.
C : 11
B : 10
A : 01
D : 001
E : 000
So my string will look like 011011001000 but I couldn't come back. How can I return to my first original string? Is there any example code for Delphi-Pascal?
If I find any examples, I will understand what I need to do. But I couldn't find any examples.
Thank you..
My codes:
button1.onclick.etc..
var
s,z:string;
i:integer;
begin
s:='ABCDE';
for i:=1 to Length(s) do
if s[i]='A' then
z:=z+'01'
else if s[i]='B' then
z:=z+'10'
else if s[i]='C' then
z:=z+'11'
else if s[i]='D' then
z:=z+'001'
else if s[i]='E' then
z:=z+'000';
end;
Showmessage(z);
end;
end.
Finally z equal to 011011001000. But how can I resolve this last string?
Like LU RD said the tomes of delphi covers this algorithm.
You'll have to buy the book, here's a link: http://www.lulu.com/shop/julian-bucknall/the-tomes-of-delphi-algorithms-and-data-structures/paperback/product-488272.html;jsessionid=5CCED10CCFDCB82897E853208BA6460A
However the sourcecode that accompanies the book is freely available; you can download the sourcecode here: http://www.boyet.com/Code/ToDADS_source.zip
Shannon-Fano is not implemented, but the closely related huffman code is see: TDHuffmn.pas.
Here's an implementation of Shannon-Fano in C:
http://cppgm.blogspot.com/2008/01/shano-fano-code.html
You simple translate the code from C into Delphi.
Starting with:
{$APPTYPE CONSOLE}
{$R *.res}
uses SysUtils;
type
node = record
sym: array[0..9] of char
pro: real;
arr: array[0..19] of integer;
top: integer;
end;
var
s: array[0..19] of node;
procedure prints(l,h: integer; s: array of node);
var
i: integer;
output: string;
begin
for i:= l to h do begin
output:= format('\n%s\t%f',s[i].sym,s[i].pro);
writeln(output);
end; {for i}
end;
procedure shannon(l,h: integer; s: array of node);
var
pack1,pack2, diff1, diff2: real;
i,d,k,j: integer;
begin
pack1=0; pack2=0; diff1=0; diff2=0;
if (((l+1)=h) or (l=h) or (l>h)) then begin
if ((l=h) or (l>h)) then
and continuing from there.
It's a pretty straightforward translation.
Related
Can anyone share what are some common Delphi examples of a function that takes a number
and returns a number that is not so obvious?
For example :
function GetNumber(const aSeed: Integer): Integer;
begin
Result := ((aSeed+5) * aSeed) + 15;
end;
So let's say the user knows that sending aSeed = 21 gives 561
and aSeed = 2, gives 29
and so on...
is there a function that makes it hard to reverse engineer the code,
even if one can generate a large number sets of Seed/Result ?
(hard : I do not mean impossible, just need to be non-trivial)
Preferably a function that does not allow in function result exceeding the
Integer result as well.
In any case, if you are not sure whether it's hard/impossible to reverse,
do feel free to share what you have.
some other requirements:
the same input always results in the same output; cannot have Random output
the same output regardless of platform: windows/android/mac/ios
won't result in some extraordinary big number (fit in Integer)
Using a hash is a very good way to achieve what you want. Here is an example that takes an integer, converts it to a string, appends it to a salt, computes the MD5 and returns the integer corresponding to the first 4 bytes:
uses
System.Hash;
function GetHash(const s: string): TBytes;
var
MD5: THashMD5;
begin
MD5 := THashMD5.Create;
MD5.Update(TEncoding.UTF8.GetBytes(s));
Result := MD5.HashAsBytes;
end;
function GetNumber(Input: Integer): Integer;
var
Hash: TBytes;
p: ^Integer;
begin
Hash := GetHash('secret' + IntToStr(Input));
P := #Hash[0];
Result := Abs(P^);
end;
procedure TForm1.Button1Click(Sender: TObject);
begin
ShowMessage(IntToStr(GetNumber(1))); // 996659739
ShowMessage(IntToStr(GetNumber(2))); // 939216101
ShowMessage(IntToStr(GetNumber(3))); // 175456750
end;
I started learning Pascal :) and I was interested on making a kind of Euromillion... However, I don't know how to forbid the same numbers or stars...
I thought this (below) would solve it... But it didn't... Help?
Program euromillion;
var num: array [1..5] of integer;
Procedure numbers;
var i, j: integer;
Begin
write ('Digite o número 1: ');
readln (num[1]);
for i:=2 to 5 do
for j:=1 to (i-1) do
Begin
repeat
write ('Digite o número ', i, ': ');
readln (num[i]);
until (num[i]>=1) and (num[i]<=50) and ((num[i]=num[j])=false);
End;
End;
Begin
numbers;
readln();
End.
Thanks guys :)
Although it is tempting to try and write a single block of code, as you have, it is better not to. Instead, a better way to write a program like this
is to think about splitting the task up into a number of procedures or functions
each of which only does a single part of the task.
One way to look at your task is to split it up into sub-tasks, as follows:
You prompt the user to enter a series of numbers
Once each number is entered, you check whether it is already in the array
If it isn't, you enter it in the array, otherwise prompt the user for another number
Once the array is filled, you output the numbers in the array
So, a key thing is that it would be helpful to have a function that checks whether
a new number is already in the array and returns True if it is and False otherwise. How to do that is the answer to your question.
You need to be careful about this because if you use the array a second time in the
program, you need to avoid comparing the new number with the array contents from
the previous time. I deliberately have not solved that problem in the example code below, to leave it as an exercise for the reader. Hint: One way would be to write a procedure which "clears" the array before each use of it, e.g. by filling it with numbers which are not valid lottery numbers, like negative numbers or zero. Another way would be to define a record which includes the NumberArray and a Count field which records how many numbers have been entered so far: this would avoid comparing the new number to all the elements in the
array and allow you to re-use the array by resetting the Count field to zero before calling ReadNumbers.
program LotteryNumbers;
uses crt;
type
TNumberArray = array[1..5] of Integer;
var
Numbers : TNumberArray;
Number : Integer;
function IsInArray(Number : Integer; Numbers : TNumberArray) : Boolean;
var
i : Integer;
begin
Result := False;
for i:= Low(Numbers) to High(Numbers) do begin
if Numbers[i] = Number then begin
Result := True;
break;
end;
end
end;
procedure ReadNumbers(var Numbers : TNumberArray);
var
i : Integer;
NewNumber : Integer;
OK : Boolean;
begin
// Note: This function needs to have a check added to it that the number
// the user enters is a valid lottery number, in other words that the
// number is between 1 and the highest ball number in the lottery
for i := Low(Numbers) to High(Numbers) do begin
repeat
OK := False;
writeln('enter a number');
ReadLn(NewNumber);
OK := not IsInArray(NewNumber, Numbers);
if not OK then
writeln('Sorry, you''ve already chosen ', NewNumber);
until OK;
Numbers[i] := NewNumber;
end;
end;
procedure ListNumbers(Numbers : TNumberArray);
var
i : Integer;
begin
for i := Low(Numbers) to High(Numbers) do
writeln(Numbers[i]);
end;
begin
ReadNumbers(Numbers);
ListNumbers(Numbers);
writeln('press any key');
readkey;
end.
I was trying to use same printing procedure for two types of arrays(1st arry length was 10, 2nd array length was 15).
I could not find any solution over internet. Did any one have any solution for this problem.
this is the Two arrays
program pp1;
const
m=10;
n=15;
type
matrix1=array[1..m] of integer;
matrix2=array[1..n] of integer;
var
m1:matrix1;
m2:matrix2;
this is the method which it tried. in method 'x' mens the length of the array.
procedure writeMatrix(var data: array of integer ;x:integer);
var
j:integer;
begin
for j:=1 to x do
begin
write(data[j]:3);
end;
end;
my main method
begin
writeMatrix(m1,10);
writeMatrix(m2,10);
end.
How can i use the same this writeMatrix method to print both of the arrays.. Is there any stranded way to do it.
As I said in my comment before, your implementation is fine, but you have to put something in your matrix before printing it, or you will get a bunch of zeroes in the screen (in the best).
Try this:
program pp1;
const
m=10;
n=15;
type
matrix1=array[1..m] of integer;
matrix2=array[1..n] of integer;
var
m1:matrix1;
m2:matrix2;
procedure fillMatrix(var data:array of integer; x:integer);
var
j:integer;
begin
for j:= 1 to x do begin
data[j]:=j;
end;
end;
procedure writeMatrix(var data: array of integer; x:integer);
var
j:integer;
begin
for j:=1 to x do
begin
write(data[j]:3);
end;
end;
begin
fillMatrix(m1,10);
fillMatrix(m2,10);
writeMatrix(m1,10);
writeMatrix(m2,10);
readln;
readln;
end.
Hint: consider avoid using global variables, m1 and m2 in this case should be declared in the main program.
How can i use the same this writeMatrix method to print both of the arrays.. Is there any stranded way to do it.
Yes, there is a standard way to this. It is called conformant-array parameters. It is standardized in (level 1) of the ISO standard 7185 (Standard “Unextended” Pascal). It looks like this:
procedure print(protected matrix: array[
columnMinimum..columnMaximum: integer;
rowMinimum..rowMaximum: integer
] of integer);
const
totalWidth = 6;
var
x: type of columnMinimum;
y: type of rowMinimum;
begin
for y := rowMinimum to rowMaximum do
begin
for x := columnMinimum to columnMaximum do
begin
write(matrix[x, y]:totalWidth);
end;
writeLn;
end;
end;
It’s as if there were additional const values, but they are dynamic depending on the passed matrix. This code furthermore uses type inquiries (type of …) and the protected modifier, both defined in ISO 10206 (Extended Pascal) which builds on top of ISO 7185. In EP you could and would also consider schemata to pass such data as parameters.
i have to do the following thing.
Make a program in Pascal that after has read a text with a list of nums., it will return the numb. of the nums that appear less than one times in the text.
The text that will be read from the program should be like that.
In the first line there are two nums. seperated by a space, n and m. N is the number of nums that exist, like if the text contains the numbers 1,2,3,4, n is 4 (1..n). M is how many lines follow. Every line has a couple of nums, a,b, (1=b) a and b are separated by a space.
The file that the program will make will have written on it a num., that says how many nyms are appeared less than two tims in the text.
All the nums. are Integer.
0=
I have finished it, but the problem is that at the new text that p has to be written, p is always 1, For me the problem is at the place that i have the bold letters, it might be because i in count and i in a arrays are different, how can i correct this???
Thank you in advance.
program MyProgr;
var
F: text;
t:Textfile;
a,count:array of Integer;
b:Integer;
i,int:Integer;
countnums:Integer;
n,m:String;
lin,nums:Integer;
Small,Big:Integer;
procedure DoWhatEver(S: string);
begin
val(s,int);
Write(s,' ');
for i:=Small to Big do
if (a[i]=int) then
count[i]:=count[i]+1;
end;
procedure FilltheArray;
begin
for i:=Small to Big do
a[i]:=i+1 ;
end;
procedure ProcessString;
var
Strng, S: string;
Last, P: integer;
begin
readln(F,Strng);
Last:=0;
while Last<length(Strng) do
begin
P:=Last+1;
while (P<=length(Strng)) and (Strng[P]<>' ') do
inc(P);
S:=copy(Strng,Last+1,(P-Last-1));
DoWhatEver(S);
Last:=P;
end
end;
procedure ProcessStringA;
var
Strng: string;
Last, P: integer;
begin
readln(F,Strng);
Last:=0;
while Last<length(Strng) do
begin
P:=Last+1;
while (P<=length(Strng)) and (Strng[P]<>' ') do
inc(P);
n:=copy(Strng,Last+1,(P-Last-1));
Val(n,nums);
Last:=P;
end
end;
procedure ProcessStringB;
var
Strng: string;
Last, P: integer;
begin
readln(F,Strng);
Last:=0;
while Last<length(Strng) do
begin
P:=Last+1;
while (P<=length(Strng)) and (Strng[P]<>' ') do
inc(P);
m:=copy(Strng,Last+1,(P-Last-1));
Val(m,lin);
Last:=P;
end
end;
begin
assign(F,'myfile.txt');
reset(F);
ProcessStringA;
Writeln(nums);
ProcessStringB;
Writeln(lin);
setlength(a,nums);
Small:=Low(a);
Big:=High(a);
for i:= Small to big do
count[i]:=0;
FillTheArray;
while not eof(F) do
ProcessString;
for i:=Small to Big do
begin
if count[i]=2 then
countnums:=countnums+1;
end;
Close(f);
Assign(t,'fileout.txt');
Rewrite(t);
Writeln(t,countnums);
close(t);
end.
I'm using Pascal. I have a problem when dealing with reading file.
I have a file with integer numbers. My pascal to read the file is:
read(input, arr[i]);
if my file content is 1 2 3 then it's good but if it is 1 2 3 or 1 2 3(enter here) (there is a space or empty line at the end) then my arr will be 1 2 3 0.
From what I can recall read literally reads the file as a stream of characters, of which a blank space and carriage return are, but I believe these should be ignored as you are reading into an integer array. Does your file actually contain a space character between each number?
Another approach would be to use readLn and have the required integers stored as new lines in the file, e.g.
1
2
3
I have tested the problem on Delphi 2009 console applications. Code like this
var
F: Text;
A: array[0..99] of Integer;
I, J: Integer;
begin
Assign(F, 'test.txt');
Reset(F);
I:= -1;
while not EOF(F) do begin
Inc(I);
Read(F, A[I]);
end;
for J:= 0 to I do write(A[J], ' ');
Close(F);
writeln;
readln;
end.
works exactly as you have written. It can be improved using SeekEOLN function that skips all whitespace characters; the next code does not produce wrong additional zero:
var
F: Text;
A: array[0..99] of Integer;
I, J: Integer;
begin
Assign(F, 'test.txt');
Reset(F);
I:= -1;
while not EOF(F) do begin
if not SeekEOLN(F) then begin
Inc(I);
Read(F, A[I]);
end
else Readln(F);
end;
for J:= 0 to I do write(A[J], ' ');
Close(F);
writeln;
readln;
end.
Since all that staff is just a legacy in Delphi, I think it must work in Turbo Pascal.
You could read the string into a temporary and then trim it prior to converting it.
It doesnt hurt to mention basics like what type of Pascal on what platform you're using in order that people can give a specific answer (as the article notes, there isnt a nice way OOTB in many Pascals)
If I recall there was a string function called Val that converts a string to a number...my knowledge of Pascal is a bit rusty (Turbo Pascal v6)
var
num : integer;
str : string;
begin
str := '1234';
Val(str, num); (* This is the line I am not sure of *)
end;
Hope this helps,
Best regards,
Tom.