When creating a procedural data type, Free Pascal throws a strange error. But I'm passing one parameter, why is the number of parameters incorrect?
Type
Func = Function (x:Real):Real;
Function middlfunc(a, b:Real; n:Integer; f:Func): Real;
Var
x,s,d: Real; k:Integer;
Begin
d:=(b-a)/n;
s:=0;
For k:=0 To n Do
Begin
x:=a+k*d;
s:=s+f(x);
End;
middlfunc:=s/(n+1);
End;
Function f1(x:Real):Real; {There is the error}
Begin
f1:=x*x;
End;
Var
mf1:Real;
a, b: real;
n: integer;
Begin
a := 0;
b := 3.1415;
n := 100;
mf1 := middlfunc(a,b,n,f1); {ERROR :((((((((}
WriteLn(mf1)
End.
USE PASCAL PROCEDURE INSTEAD OF FUNCTION for suitability
If you want to use a Function as a parameter to another function, then you have to do it like this:
Type
TFunctionParameter = function(x: Real): Real;
Function middlfunc(a, b:Real; n:Integer; f:TFunctionParameter): Real;
Var
x,s,d: Real; k:Integer;
Begin
d:=(b-a)/n;
s:=0;
For k:=0 To n Do
Begin
x:=a+k*d;
s:=s+f(x);
End;
middlfunc:=s/(n+1);
End;
function RaiseToSecondPower(x: Real): Real;
begin
result := x*x;
end;
Var
mf1:Real;
a, b: real;
n: integer;
Begin
a := 0;
b := 3.1415;
n := 100;
mf1 := middlfunc(a,b,n,RaiseToSecondPower);
WriteLn(mf1)
End.
Related
I am studying Pascal and have a problem.
My code needs to make combinations of four numbers, from left to right but I want to prevent those combinations from repeating the same thing being the numbers in positions, but worth the same thing from right to left.
Does anyone have any idea how to do that?
program mistureba;
type
placa = array [1..4] of integer;
var
a4num : array [1..24] of placa; // a4num : array [1..24,1..4] of integer
linha : integer;
const
MAXDIG = 4;
procedure mistura(input : placa; index : integer);
// input tem a série de digitos da placa
// index indica a posição que inicia o arranjo
var
output : placa;
p, i : integer;
begin
if index = MAXDIG then
begin // mostra / insere a sequencia que está em input
//for i := 1 to MAXDIG do
//write(input);
//writeln;
a4num[linha] := input;
linha := linha + 1;
end
else
begin
output := input;
for p := index to MAXDIG do
begin
output[index] := input[p];
for i := index to p - 1 do
output[i + 1] := input;
for i := p + 1 to MAXDIG do
output := input;
mistura(output,index + 1);
end;
end;
end;
var
//a4num : placa;
p, i : integer;
begin
linha := 1;
for i := 1 to MAXDIG do
readln(a4num[linha, i]);
mistura(a4num[linha], 1);
// vou mostrar o conteúdo do meu conjunto de placas
for linha := 1 to 24 do
if [i, 1] = [i, 4] then
begin
for i := 1 to MAXDIG do
write(a4num[linha, i]);
writeln;
end
else
begin
writeln('0');
end;
if [i,2] = [i,3] then
begin
for i := 1 to MAXDIG do
write(a4num[linha, i]);
writeln;
end
else
begin
writeln('0');
end;
end.
It was still not very clear what you wanted, so here are four solutions. You can choose the one you like:
program license;
uses
classes;
type
tIntegers = array of integer;
procedure BuildPermutation(aInput : string; aUsedCharacters : tIntegers; aBuild : string; var aOutput : tStringList);
var
i, j : integer;
Used : boolean;
begin
for i := 1 to length(aInput) do
begin
Used := false;
for j := 0 to length(aBuild) -1 do
if aUsedCharacters[j] = i then
begin
Used := true;
break;
end;
if not Used then
begin
aUsedCharacters[length(aBuild)] := i;
aBuild := aBuild + aInput[i];
if length(aBuild) = length(aInput) then
aOutput.Add(aBuild)
else
BuildPermutation(aInput, aUsedCharacters, aBuild, aOutput);
SetLength(aBuild, length(aBuild) - 1);
end;
end;
end;
function AllPermutations(aInput : string) : tStringList;
var
UsedCharacters : tIntegers = nil;
i : integer;
begin
result := tStringList.Create;
SetLength(UsedCharacters, length(aInput));
for i := 0 to length(UsedCharacters) - 1 do
UsedCharacters[i] := 0;
BuildPermutation(aInput, UsedCharacters, '', result);
end;
function WithoutDuplicatesSorted(aInput : tStringList) : tStringList;
// very easy using a built in feature of tStringList
var
OnePlate : string;
begin
result := tStringList.Create;
result.Sorted := true;
result.Duplicates := dupIgnore;
for OnePlate in aInput do
result.Add(OnePlate);
end;
function WithoutDuplicatesUnsorted(aInput : tStringList) : tStringList;
var
OnePlate : string;
begin
result := tStringList.Create;
for OnePlate in aInput do
if result.IndexOf(OnePlate) = -1 then
result.Add(OnePlate);
end;
function WithoutMirrors(aInput : tStringList) : tStringList;
var
OnePlate : string;
Mirror : string;
i : integer;
begin
result := tStringList.Create;
for OnePlate in aInput do
begin
Mirror := '';
for i := 1 to length(OnePlate) do
Mirror := OnePlate[i] + Mirror;
if result.IndexOf(Mirror) = -1 then
result.Add(OnePlate);
end;
end;
function WithoutMirrorsAndDuplicates(aInput : tStringList) : tStringList;
var
OnePlate : string;
Mirror : string;
i : integer;
begin
result := tStringList.Create;
for OnePlate in aInput do
if result.IndexOf(OnePlate) = -1 then
begin
Mirror := '';
for i := 1 to length(OnePlate) do
Mirror := OnePlate[i] + Mirror;
if result.IndexOf(Mirror) = -1 then
result.Add(OnePlate);
end;
end;
procedure PrintResult(aTitle : string; aInput : tStringList);
var
OnePlate : string;
begin
writeln(aTitle);
for OnePlate in aInput do
writeln(OnePlate);
end;
procedure Solve;
var
Input : string = '';
Intermediate : tStringList = nil;
FinalResult : tStringList = nil;
begin
// get one version of the license plate
// please note that it allows non-numeric characters
// if you want, you can insert a filtering, or any other mechanism to ensure only numeric license plates
writeln('Input one version of the license plate:');
readln(Input);
// make all possible permutations and print them
Intermediate := AllPermutations(Input);
PrintResult('All permutations', Intermediate);
// option 1 - filter identical ones (and also sorting them to make it easy)
FinalResult := WithoutDuplicatesSorted(Intermediate);
PrintResult('Without duplicates sorted', FinalResult);
FinalResult.Free;
// option 2 - filter identical ones (without sorting them, i.e. more complicated)
FinalResult := WithoutDuplicatesUnsorted(Intermediate);
PrintResult('Without duplicates unsorted', FinalResult);
FinalResult.Free;
// option 3 - filter mirrors (be careful, it is not defined which one of 123 and 321 will be shown!!!)
FinalResult := WithoutMirrors(Intermediate);
PrintResult('Without mirrors', FinalResult);
FinalResult.Free;
// option 3 - filter mirrors and duplicates
FinalResult := WithoutMirrorsAndDuplicates(Intermediate);
PrintResult('Without mirrors and duplicates', FinalResult);
FinalResult.Free;
Intermediate.Free;
end;
begin
Solve;
end.
Huge amount of numeric data (from a database) is stored in a Tstringlist variable. the Data may look like:
4
4 1/2
12.006
13 3/8
1.05
13.25
5 1/2
2.25
13 5/8
By setting the sort property of the Tstringlist to true, they are sorted as texts and as a result, 13.25 shows up before 4.
How can these data be sorted numerically (and efficiently)?
(Delphi, Rad Studio 10.4)
Here is a solution:
// Conversion accepting input like '4', '4.003', '4 1/2' or '1/4'
// No leading or trailing space allowed (use trim if required).
function MyStrToFloat(const S : String) : Double;
var
I, J : Integer;
FS : TFormatSettings;
begin
I := Pos('/', S);
if I > 0 then begin
// We have a fractional part
J := Pos(' ', S);
if J > 0 then
// Both integer and fractional parts
Result := StrToInt(Trim(Copy(S, 1, J - 1)))
else
Result := 0;
Result := Result + StrToInt(Trim(Copy(S, J + 1, I - J - 1))) /
StrToInt(Trim(Copy(S, I + 1)));
end
else begin
FS.DecimalSeparator := '.';
Result := StrToFloat(S, FS);
end;
end;
function StringListSortProc(
List : TStringList;
Index1 : Integer;
Index2 : Integer): Integer;
var
N1, N2: Double;
begin
N1 := MyStrToFloat(List[Index1]);
N2 := MyStrToFloat(List[Index2]);
if N1 > N2 then
Result := 1
else if N1 < N2 then
Result := -1
else
Result := 0;
end;
procedure TForm1.Button1Click(Sender: TObject);
var
SL : TStringList;
S : String;
begin
SL := TStringList.Create;
try
SL.Add('4');
SL.Add('1/2');
SL.Add('4 1/2');
SL.Add('12.006');
SL.Add('13 3/8');
SL.Add('1.05');
SL.Add('13.25');
SL.Add('5 1/2');
SL.Add('2.25');
SL.Add('13 5/8');
Memo1.Lines.Add('Raw:');
for S in SL do
Memo1.Lines.Add(S);
SL.CustomSort(StringListSortProc);
Memo1.Lines.Add('Sorted:');
for S in SL do
Memo1.Lines.Add(S);
finally
SL.Free;
end;
end;
The conversion is done in the sorting which is not very efficient. It is probably better to create a new list with converted values and then sort it. Or convert when loading the list from database. You've got the idea...
Two components solve your problem:
StrCmpLogical is your friend. It uses Natural sorting - Digits in the strings are considered as numerical content rather than text.
And this SO post How do I enter fractions in Delphi?
I put it together below:
unit Unit1;
interface
uses
Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls;
type
TForm1 = class(TForm)
Memo1: TMemo;
ButtonSort: TButton;
Memo2: TMemo;
procedure ButtonSortClick(Sender: TObject);
private
{ Private declarations }
public
{ Public declarations }
end;
//Natural sorting - Digits in the strings are considered as numerical content rather than text. This test is not case-sensitive.
function StrCmpLogicalW(P1, P2: PWideChar): Integer; stdcall; external 'Shlwapi.dll';
function StrCmpLogical(const S1, S2: string): Integer;
var
Form1: TForm1;
implementation
{$R *.dfm}
function StrCmpLogical(const S1, S2: string): Integer;
begin
result := StrCmpLogicalW(PChar(S1), PChar(S2));
end;
function CustomNbrSort(List: TStringList; Index1, Index2: Integer): Integer;
begin
result := StrCmpLogical(List[index1], List[index2]);
end;
procedure DoCustomSort(const List : TStringList);
begin
List.CustomSort(CustomNbrSort);
end;
// https://stackoverflow.com/questions/18082644/how-do-i-enter-fractions-in-delphi
function FractionToFloat(const S: string): real;
var
BarPos: integer;
numStr, denomStr: string;
num, denom: real;
begin
BarPos := Pos('/', S);
if BarPos = 0 then
Exit(StrToFloat(S));
numStr := Trim(Copy(S, 1, BarPos - 1));
denomStr := Trim(Copy(S, BarPos + 1, Length(S)));
num := StrToFloat(numStr);
denom := StrToFloat(denomStr);
result := num/denom;
end;
function FullFractionToFloat(S: string): real;
var
SpPos: integer;
intStr: string;
frStr: string;
int: real;
fr: real;
begin
S := Trim(S);
SpPos := Pos(' ', S);
if SpPos = 0 then
Exit(FractionToFloat(S));
intStr := Trim(Copy(S, 1, SpPos - 1));
frStr := Trim(Copy(S, SpPos + 1, Length(S)));
int := StrToFloat(intStr);
fr := FractionToFloat(frStr);
result := int + fr;
end;
procedure TForm1.ButtonSortClick(Sender: TObject);
begin
var MyList : TStrings := TStringList.Create;
try
//MyList.Assign(Memo1.Lines);
var MyFormatSettings : TFormatSettings := FormatSettings; //Make a copy of the global variable;
MyFormatSettings.DecimalSeparator := '.'; //The system's seporator may be a comma ','
for var i : integer := 0 to Memo1.Lines.Count - 1 do begin
var s : string := Memo1.Lines[i];
if not s.Contains('.') then
s := FloatToStr(FullFractionToFloat(s), MyFormatSettings);
MyList.AddObject(s, TObject(i));
end;
TStringList(MyList).CustomSort(CustomNbrSort);
Memo2.Lines.Clear;
for var i : integer := 0 to Memo1.Lines.Count - 1 do
Memo2.Lines.Add(Memo1.Lines[Integer(MyList.Objects[i])]);
finally
MyList.Free;
end;
end;
end.
Following is a program in lazarus to perform RC4 encryption and decryption when given a string. When the compiler directive {$mode fpc} is used and the string 123 is entered it crashes with External: SIGSEGV. However there is no crash when inputting the same string in {$mode objfpc}. Another inconsistency is that in {$mode objfpc} the program raises the exception External: SIGSEGV again with the input of hellow.
//{$mode fpc}
{$mode objfpc}
program project1;
uses
sysutils, strutils;
type
myArray = array[0..255] of integer;
dynamicArray = array of integer;
dynamicArrayString = array of string;
const
key = 'qwertyui';
var
plaintext : string;
function KSA(const key: string): myArray;
var
i, j, key_length, temp: integer;
S : myArray;
begin
key_length := length(key);
j := 0;
for i := Low(S) to High(S) do
S[i] := i;
for i := Low(S) to High(S) do
begin
j := ((j + S[i] + ord(key[i mod key_length + 1])) mod 256);
temp := S[i];
S[i] := S[j];
S[j] := temp;
end;
KSA := S;
end;
function PRGA(S : myArray; n : integer) : dynamicArray;
var
i, j, K, temp, sizeOfArray : integer;
key : dynamicArray;
begin
i := 0;
j := 0;
K := 0;
temp := 0;
sizeOfArray := n - 1;
SetLength(key, sizeOfArray);
while n > 0 do
begin
n := n - 1;
i := (i + 1) mod 256;
j := (j + S[i]) mod 256;
temp := S[i];
S[i] := S[j];
S[j] := temp;
K := S[(S[i] + S[j]) mod 256];
key[i-1] := K;
end;
PRGA := key;
end;
procedure getPlaintext;
begin
readln(plaintext);
end;
function encrypt : string;
var
sizeOfArray, i : integer;
cipherString : string;
cipher, keystream: dynamicArray;
S : myArray;
begin
S := KSA(key);
keystream := PRGA(S, length(plaintext));
sizeOfArray := 0;
for i := 0 to (length(plaintext) - 1) do
begin
sizeOfArray := sizeOfArray + 1;
SetLength(cipher, sizeOfArray);
cipher[i] := (keystream[i]) xor (ord(plaintext[i + 1]));
end;
cipherString := '';
for i := 0 to High(cipher) do
cipherString := cipherString + IntToHex(cipher[I], 2);
encrypt := cipherString;
end;
function stringToHex(cipherString : string) : dynamicArrayString;
var
sizeOfArray, i: integer;
DecryptArrayString : dynamicArrayString;
begin
sizeOfArray := 0;
i := 0;
// Turn the string into an array of hex
while length(cipherString) > 0 do
begin
sizeOfArray := sizeOfArray + 1;
SetLength(DecryptArrayString, sizeOfArray);
DecryptArrayString[i] := cipherString[1] + cipherString[2];
i := i + 1;
cipherString := rightstr(cipherString, length(cipherString) - 2);
end;
stringToHex := DecryptArrayString;
end;
function hexToDecimal(DecryptArrayString : dynamicArrayString) : dynamicArray;
var
sizeOfDecryptArrayInt, i : integer;
DecryptArrayInt : dynamicArray;
begin
sizeOfDecryptArrayInt := 0;
// Hex to decimal
for i := 0 to high(DecryptArrayString) do
begin
sizeOfDecryptArrayInt := sizeOfDecryptArrayInt + 1;
SetLength(DecryptArrayInt, sizeOfDecryptArrayInt);
DecryptArrayInt[i] := Hex2Dec(DecryptArrayString[i]);
end;
hexToDecimal := DecryptArrayInt;
end;
function decrypt(DecryptArrayInt : dynamicArray) : string;
var
DecryptedString : string;
S : myArray;
keystream, Decrypted : dynamicArray;
sizeOfArray, i : integer;
begin
sizeOfArray := 0;
for i := 0 to high(DecryptArrayInt) do
begin
sizeOfArray := sizeOfArray + 1;
SetLength(Decrypted, sizeOfArray);
S := KSA(key);
keystream := PRGA(S, length(plaintext));
Decrypted[i] := (keystream[i] xor DecryptArrayInt[i]);
end;
decryptedString := '';
// Turn array to string
for i := 0 to high(Decrypted) do
decryptedString := decryptedString + chr(Decrypted[i]);
decrypt := decryptedString;
end;
procedure encryptDecrypt;
var
cipherString, DecryptedString : string;
DecryptArrayString : dynamicArrayString;
DecryptArrayInt : dynamicArray;
begin
cipherString := encrypt;
writeln(cipherString);
DecryptArrayString := stringToHex(cipherString);
DecryptArrayInt := hexToDecimal(DecryptArrayString);
DecryptedString := decrypt(DecryptArrayInt);
writeln(DecryptedString);
end;
begin
getPlaintext;
encryptDecrypt;
readln;
end.
I've not been able to find the many specific cases that makes the program crash apart from a string of any three characters will always crash in {$mode fpc} but not in {$mode objfpc}
You should debug (and watch) your code so any error can be traced more easily. Use the FP IDE, it helps a lot.
Meanwhile, watch this line:
keystream := PRGA(S, length(plaintext));
And inside the PRGA function watch these lines:
sizeOfArray := n - 1;
SetLength(key, sizeOfArray);
What's wrong here? Well, suppose "plaintext" has only 1 character. So, "Length(plaintext)"=1, right? In PRGA you do "sizeOfArray:= n-1;", so sizeOfArray = 0. When you do SetLength, "Key" will be NIL because you're indicating a zero indexes length. Later, on loop, you have:
key[i-1] := K;
the program will fail because you are accessing at index 0 and the Key variable is NIL.
Careful: On "SetLength(key, sizeOfArray);" valid indexes for key are in range [0..sizeOfArray-1], but sizeOfArray must be at least 1 to be valid (sizeOfArray >= 1).
So, you should check your PRGA function. It's up to you to find the definitive solution. Don't give up. Good luck!
this is my simple code to generate
all possible combinations of a set for
example
1,2,3:
Display:
123
132
213
231
312
321
i want to create variable number of for loops to let the user determine the length of given string...
does anyone have an idea...
thank's in advance.
type
TNumber = '0'..'9';
procedure TForm1.Button1Click(Sender: TObject);
var
Numbers: array[0..3] of TNumber;
a, b, c, d: Integer;
s: string;
begin
Numbers[0] := '1';
Numbers[1] := '8';
Numbers[2] := '7';
Numbers[3] := '2';
for a := low(Numbers) to High(Numbers) do
for b := low(Numbers) to High(Numbers) do
for c := low(Numbers) to High(Numbers) do
for d := low(Numbers) to High(Numbers) do
begin
s := Numbers[a] + Numbers[b] + Numbers[c] + Numbers[d];
if
(Occurrences('1', s) > 1 ) or
(Occurrences('8', s) > 1 ) or
(Occurrences('7', s) > 1 ) or
(Occurrences('2', s) > 1 )
then
Continue
else
Memo1.Lines.Add(s);
end;
end;
function TForm1.Occurrences(const Substring, Text: string): Integer;
var
Offset: Integer;
begin
Result := 0;
Offset := PosEx(Substring, Text, 1);
while Offset <> 0 do
begin
Inc(Result);
Offset := PosEx(Substring, Text, offset + length(Substring));
end;
end;
end.
Here is some code that produces the output you desire. You'd need to work it around a bit for your needs, but the concept expressed in this recursive solution is the important thing:
program Permuatations;
{$APPTYPE CONSOLE}
type
TElements = '1'..'3';
procedure EnumerateCombinations(const Stem: string; Len: Integer);
var
i: Integer;
el: TElements;
Used: set of TElements;
begin
if Len=0 then
exit;
Used := [];
for i := 1 to Length(Stem) do
Include(Used, Stem[i]);
for el := low(el) to high(el) do
begin
if el in Used then
continue;
if Len=1 then
Writeln(Stem+el)
else
EnumerateCombinations(Stem+el, Len-1)
end;
end;
procedure Main;
begin
EnumerateCombinations('', 1+ord(high(TElements))-ord(low(TElements)));
end;
begin
Main;
Readln;
end.
Output:
123
132
213
231
312
321
If you change the definition of TElements, for example to '1'..'4' then you will see the 24 possible permutations.
I'm writing assembler for imaginary processor of my design (kinda like DCPU-16) and I want to include all major number bases. I've got hex,bin and dec, but I cannot get oct, because there seem to be no OctToInt function. Any help?
function OctToInt(Value: string): Longint;
var
i, int: Integer;
begin
int := 0;
for i := 1 to Length(Value) do
int := int * 8 + StrToInt(Copy(Value, i, 1));
Result := int;
end;