Need a pascal programmer with time on their hands

I have a problem, I was given this code by a teacher of mine for an assignment. The problem is, is that I don't know what the program code means, the program is supposed to arrange ten numbers into ascending or descending order. She only did the ascending code and made the code so that it will accept 3 numbers, so that we can expand it. But I can't understand what the code is doing. Now I went out on a limb and attempted to create the descending code, but that odesn't work as i do not now what the hell this code is doing.

Code:

---

{This is a simple program that will sort 3 numbers, and will allow the user
 to either choose to sort the number in ascending order or descending order.

 Created: NAMEHID
 BLAHBLAHBLAH}

Program sortup_sortdown(Input,output);
Uses Wincrt;

VAR
        Num: array [1..3] of integer;
        Biggest            :integer;                 
        smallnum            :integer;
        currentnum          :integer;
        Choice              :char;

Procedure getnums;
Var loop :integer;

Begin
        Writeln('Enter The Three Numbers');              {Title, giving instruction}
        for loop:=1 to 3 do                              {when loop appears, it will show
                                                          1 to 3}

Begin
        Write('Enter number ',loop, ':');                {enter the number <loop>, or enter
                                                          number 1}
        readln(Num[loop])                                {Read the first number entered}
      end
      End;

Procedure findthesmallest;                             
var loop :integer;

Begin
        Smallnum:=Currentnum;
For    loop:=currentnum to 3 do
IF      num[loop] <num[smallnum] then smallnum:=loop;
        End;

Procedure findbiggest;
var loop :integer;

Begin
        Biggest:=currentnum;
For    loop:=currentnum to 3 do
IF      Num[loop] >num[biggest] then biggest:=loop;
        end;

Procedure upsort;
var loop, temp:integer;

Begin
        write('In sort Up Procedure ');
For    loop:=1 to 3 do                        {For the 3 numbers entered, do the next
                                                code}

Begin
        Currentnum:=loop;
        findthesmallest;
        temp:=num[smallnum];
        num[smallnum]:=num[currentnum];
        num[currentnum]:=temp;
        End
        End;

Procedure downsort;
var loop, temp:integer;

Begin
        write('In Sort Down Procedure ');
For    Loop:=1 to 3 do

Begin
      Currentnum:=loop;
      findbiggest;
      temp:=num[biggest];
      num[biggest]:=num[currentnum];
      num[Currentnum]:=temp;
      End
      End; 

Procedure Shownums;
var loop :integer;

Begin
        Writeln('The sorted numbers are:');
For    Loop :=1 to 3 do

Begin
        Writeln(loop:2, ': ',num[loop]);
        End
        End;

Begin {Main Body}

        Getnums;
        writeln('Type A=Ascending D=Descending');
        Readln (Choice);
If      Choice='A' then upsort;
{If choice='D' the downsort;}
        Shownums
        End.

---

I was hoping for someone to do a pseudocode for this? maybe taht could help me understand.

oh yeah and the comments on the side is all that I understood from what was given :blink:

First thing I'll say is that you really should have a nested approach to the program (e.g. have the loop body on the line below the line header, indented). But I digress.

I used to do PASCAL, but now I usually code with C. I'll see what I can do with what I remember though.

hi mate;

thanks alot, any news yet?

I never learnt pascal, but i can do my best to explain part of that code for you.

Quote:

---

VAR
Num: array [1..3] of integer;
Biggest :integer;
smallnum :integer;
currentnum :integer;
Choice :char;

---

Declaring variables, and one is an array that stores your numbers. You will need to change that to an array of 10 (set to 3 atm) when you make it 10 numbers.

Quote:

---

Procedure getnums;
Var loop :integer;

Begin
Writeln('Enter The Three Numbers'); {Title, giving instruction}
for loop:=1 to 3 do {when loop appears, it will show
1 to 3}

Begin
Write('Enter number ',loop, ':'); {enter the number <loop>, or enter
number 1}
readln(Num[loop]) {Read the first number entered}
end
End;

---

Does a loop for each number that the program will ask.
Displays "Enter Number X" where X is the 'loop' variable.

Quote:

---

Procedure findthesmallest;
var loop :integer;

Begin
Smallnum:=Currentnum;
For loop:=currentnum to 3 do
IF num[loop] <num[smallnum] then smallnum:=loop;
End;

---

This part finds the smallest integer. It does a FOR loop for each of the numbers.
First it sets the first of the numbers to the smallest. It then starts the loop and if the number that the loop is on is smaller than the one that is currently set as the smallest, it sets that one to the smallest.

The biggest one works the same way, only the biggest one is found...obviously.


I can't explain the sorting tho, i don't understand how that works in pascal. ;)


Hope that helps you, maybe just a little. :unsure:

Hi, thanks for the help rossco :thumbsup: , hows the pseudo code going illuminati?

Here's a pascal example for a simple bubble-sort, ascending order..

Code:

---

{ read numbers to be sorted into the array A, where N is Number of integers }
        repeat
            Flag := true;
            for I := 1 to N - 1 do
                if (A[I] > A[I+1]) then
                    begin
                    Temp := A[I];
                    A[I] := A[I+1];
                    A[I+1] := Temp;
                    Flag := false;
                    end;
        until (Flag)

---

Basically, it keeps looping through the elements until at no time is the next element less than the current element, not too efficient, but it works well small sorts.

For sorting into descending order I guess you change the ">" to a "<"

The great thing about pseudocode is that if done right, the code writes itself :)

First things first, sort out the data. You're right in sorting numbers instead of letters (they're a lot easier to compare :D) At the start, we're talking about:

Code:

---

List[MAX] - Array of Integers (MAX = number of records)
Record - Highest/Lowest in the list

---

Once you've got your basic data stuff down (don't worry - programs almost always have more data put in ;)) in let's start at the basic ascending program in one swoop:

Code:

---

- Look up a number in an array "row"
- If row's number is higher than the Record
 - Record = ID of the row

---

The reason of using the IDs instead of the actual data themselves is so the data doesn't get tangled around. The actual data is insignificant - It's the program's job to simply sort them.

Now that code above will do it for one swoop - The next stage is to add a loop to it

Code:

---

PROCEDURE Ascending_Search

Record = 1

Do a loop of n = 1 to n = MAX
{
- Look up a number in an array "row"
- If row's number is higher than the Record
 - Record = ID of the row
}

---

That is your basic searching algorithm - It will look at each row and will end up recording the ID of the highest number in the list. Now, we have to do the actual switch.

Unfortunately, switching isn't a case of switching between the two as one line will overwrite one of the data. A third interger, temp, has to be used to hold one of the values during the switch.

Code:

---

PROCEDURE Switch
{
- Put list[n] into temp
- Put list[Record] into list[n]
- Put temp into list[Record]
}

---

The neat thing about using the IDs is that you don't need seperate procedures for switching ascending/descending - Because all it's doing is switch the data of each ID, it will work either way (yay for optimisation! :D)

Now we can put the whole thing together by declaring the switch algorithm and and also adding a record = 1 to reset it each time (a good thing to remember when using global variables) :)

Code:

---

PROCEDURE Ascending_Search

Record = 1

Do a loop of n = 1 to n = MAX
{
- Look up a number in an array "row"
- If row's number is higher than the Record
 - Record = ID of the row
}

- Execute procedure "Switch"
}

---

What that will do is reset the record counter, make a loop of looking for the row in the array that holds the highest number, and then make the switch in a three-point-turn fashion.

The next stage involves looking at the main function, the one that will start the program entirely. By this, you can also modify the search & switch procedures to compensate - Using main means you can set it so it doesn't go back on past territory ;)

Code:

---

PROCEDURE Main
Do a loop of k = 1 to k = MAX
{
- Execute procedure "Ascending_Search" (with m = k)
}

PROCEDURE Ascending_Search (parameter of m = interger)

Record = m

Do a loop of n = m to n = MAX
{
- Look up a number in an array "row"
- If row's number is higher than the Record
 - Record = ID of the row
}

- Execute procedure "Switch"
}

PROCEDURE Switch
{
- Put list[m] into temp
- Put list[Record] into list[m]
- Put temp into list[Record]
}

---

Once this works, the rest is simple - The descending one is pretty much the same but reversing the condition, and then all that is needed is to add a keyboard input how you want :)

Dunno whether it helps, but I've had a stab at writing this program in C. Although it may be a little daunting, there is usually a lot of similarities between programs so should be able to pick up the jist of it :)

Code:

---

list[5] = 3, 4, 2, 1, 9

void switch (int m, int record);
{
        int temp;

        temp = list[m];
        list[m] = list[record];
        list[record] = temp;
}

void ascending_search (int m)
{
        int record = m;

        for n = m ; n < 5 ; n++)
        {
                if list[n] > list[record]
                {
                        record = n;
                }
        }

        switch(m, record);
}

void descending_search (int m)
{
        int record = m;

        for n = m ; n < 5 ; n++)
        {
                if list[n] < list[record]
                {
                        record = n;
                }
        }

        switch(m, record);
}

void main()
{
        int k;
        char key;

        getch(key);
       
        if (key = 'a')
                for (k = 1 ; k < 5 ; k++)
                {
                        ascending_search(k);
                }
        if (key = 'd')
                for (k = 1 ; k < 5 ; k++)
                {
                        descending_search(k);
                }
}

---

Hope that helps :)

I think I understand, I have added comments to my code, can someone check if the comments are right? thanks

Code:

---

{This is a simple program that will sort 3 numbers, and will allow the
 user to either choose to sort the number in ascending order or descending order

 Created: NAMEHIDDEN}

Program sortup_sortdown(Input,output);
Uses Wincrt;

VAR
        Num: array [1..10] of integer;
        Biggest            :integer;                 
        smallnum            :integer;
        currentnum          :integer;
        Choice              :char;

{The loop is the number of the number it is asking you to enter}

Procedure getnums;
Var loop :integer;

Begin
        Writeln('Enter The Three Numbers');        {Title, giving instruction}
        for loop:=1 to 10 do                            {when loop appears, it will
                                                                show 1 to 10}

                                                         
Begin
        Write('Enter number ',loop, ':');              {enter the number <loop>,
                                                                or enter number 1}
                                                 
        readln(Num[loop])                                {Read the first number
                                                                entered}
      end
      End;

Procedure findthesmallest;                            {The title of this procedure is
                                                              findthesmallest}
var loop :integer;                                      {the loop is a variable, can be
                                                              any number}

Begin
        Smallnum:=Currentnum;                    {Set the first current number
                                                            it is reading as the smallest}
                                                     
For loop:=currentnum to 10 do                  {Each number it goes through
                                                          is set to current number}
                                                     
IF
num[loop] <num[smallnum] then smallnum:=loop; {If the current number is                                                                smaller than the current
                                                                  smallest number then 
                                                                  set that number as the
                                                                  smallest}
End;

Procedure findbiggest;
var loop :integer;

Begin
        Biggest:=currentnum;                          {Set the first current number
                                                                it is reading as the largest}
For    loop:=currentnum to 10 do                  {Each number it goes 
                                                                through is set as current
                                                                number}
IF     
Num[loop] >num[biggest] then biggest:=loop;  {If the current number is
                                                                bigger than the current
                                                                biggest number then set 
                                                                that number as the
                                                                biggest}
        end;

Procedure upsort;
var loop, temp:integer;

Begin
        write('In sort Up Procedure ');
For    loop:=1 to 10 do                            {For the 10 numbers entered,
                                                            do the next code}
Begin
        Currentnum:=loop;                       
        findthesmallest;                              {Run find the smallest
                                                          procedure}
        temp:=num[smallnum];                    {Display the smallest number
                                                            that is worked out from the 
                                                            previous procedure}
        num[smallnum]:=num[currentnum];    {Set the current smallest
                                                            number as the current number}
        num[currentnum]:=temp;                  {Set the current number as the
                                                            temp, in other words
                                                            display the number}
        End
        End;

Procedure downsort;
var loop, temp:integer;

Begin
        write('In Sort Down Procedure ');
For    Loop:=1 to 10 do

Begin
      Currentnum:=loop;
      findbiggest;                                    {Run find the biggest procedure}
      temp:=num[biggest];                        {show the biggest number that
                                                            is worked out from the
                                                            previous procedure}
      num[biggest]:=num[currentnum];        {set the current biggest number
                                                            as the current number}
      num[Currentnum]:=temp;                  {show the current number}
      End
      End; 

Procedure Shownums;
var loop :integer;

Begin
        Writeln('The sorted numbers are:');    {Display this message when this
                                                            procedure is run}
For    Loop :=1 to 10 do

Begin
        Writeln(loop:2, ': ',num[loop]);
        End
        End;

Begin {Main Body}
 
        Getnums;
        writeln('Type A=Ascending D=Descending');
        Readln (Choice);
        If      Choice='A' then upsort  ;              {If the choice is A then run 
                                                                  Upsort procedure}
        if choice='D' then downsort ;                  {If the choice is D then run
                                                                  downsort procedure}

        Shownums
        End.

---

are the comments right?

thanks a lot guys