Computer Science Canada

Program is stuck at "Executing."
Author:  gayden [ Mon Mar 02, 2015 10:36 am ]
Post subject:  Program is stuck at "Executing."
Not sure if the purpose of the program is really relevant or not, but basically it's meant to complete Shawnar's Process, which dictates: "Given any positive number, you can perform the following operations on it:
-If even, divide by two
-If odd, multiply by three and then add one
and eventually you will reach the number one.

Example: 13
13 * 3 + 1 = 40
40 / 2 = 20
20 / 2 = 10
10 / 2 = 5
5 * 3 + 1 = 16
16 / 2 = 8
8 / 2 = 4
4 / 2 = 2
2 / 2 = 1

Anyway, when I run the program it sort of pauses at line 13. The Turing window says "Executing." I am given no error.

code:
var font1 := Font.New ("Times:12")
Font.Draw ("Shawnar's Process", 230, 380, font1, red)

var posnum, xnum : real
var num, counter : int
var ans : string (1)
counter := 0

locate (3, 5)
put "How many numbers do you want to test? " ..
get num
for i : 1 .. num
    put "Enter the positive number for test #", i, ": " ..
    get posnum
    if (posnum <= 0) then
        put "Enter the positive number for test #", i, ": " ..
        get posnum
    else
        loop
            if (posnum mod 2 = 0) then
                xnum := posnum / 2
               
            else
                xnum := (posnum * 3) + 1
               
            end if
            exit when xnum = 1
            counter := counter + 1
        end loop
    end if
    put "It took ", counter, " iterations for ", posnum, " to reach a 1."
end for
Author:  Insectoid [ Mon Mar 02, 2015 11:23 am ]
Post subject:  RE:Program is stuck at "Executing."
code:
        loop
            if (posnum mod 2 = 0) then
                xnum := posnum / 2
               
            else
                xnum := (posnum * 3) + 1
               
            end if
            exit when xnum = 1
            counter := counter + 1
        end loop


This loop never exits under some condition. This is because posnum never changes, so unless xnum = 1 is satisfied after the first iteration of the loop, it will never exit.
Author:  gayden [ Wed Mar 04, 2015 10:34 am ]
Post subject:  Re: RE:Program is stuck at "Executing."
Insectoid @ Mon Mar 02, 2015 11:23 am wrote:
This loop never exits under some condition. This is because posnum never changes, so unless xnum = 1 is satisfied after the first iteration of the loop, it will never exit.

So if I change every isntance of 'xnum' in the program to 'posnum,' so that posnum does now change, it should work right?
edit: Now I run into more problems. I shall update when I figure it out.
edit2: Program now looks like:
code:
var font1 := Font.New ("Times:12")
Font.Draw ("Shawnar's Process", 230, 380, font1, red)

var posnum, originalnumber : real
var num, counter : int

locate (3, 1)
put "How many numbers do you want to test? " ..
get num
for i : 1 .. num
    put "Enter the positive number for test #", i, ": " ..
    get posnum
    counter := 1
    originalnumber := posnum
    loop
        if (posnum mod 2 = 0) then
            posnum := posnum / 2
        else
            posnum := (posnum * 3) + 1
        end if
        exit when posnum = 1
        counter := counter + 1
    end loop
    put "It took ", counter, " iterations for ", originalnumber, " to reach a 1."
end for


%TO DO
%Add negative fail-safe for get posnum
%Add 100 iteration continuation thing
Author:  Clayton [ Thu Mar 05, 2015 3:43 pm ]
Post subject:  RE:Program is stuck at "Executing."
What problems are you running into exactly? Not being able to test your code at the moment, so I might be missing something small, but at a glance, this appears like it should do what you're looking to do.
Author:  Tony [ Thu Mar 05, 2015 4:07 pm ]
Post subject:  RE:Program is stuck at "Executing."
Quote:

exit when posnum = 1

Does 1.0 equal to 1? Sometimes, but not always. real (known as float in other languages) are designed to for less-than and greater-than comparisons, not for equalness.
Author:  gayden [ Fri Mar 06, 2015 10:07 am ]
Post subject:  Re: RE:Program is stuck at "Executing."
Tony @ Thu Mar 05, 2015 4:07 pm wrote:
Quote:

exit when posnum = 1

Does 1.0 equal to 1? Sometimes, but not always. real (known as float in other languages) are designed to for less-than and greater-than comparisons, not for equalness.

I'm not even sure why posnum and originalnumber were declared as real numbers as opposed to integers. My mistake Razz

Clayton @ Thu Mar 05, 2015 3:43 pm wrote:
What problems are you running into exactly? Not being able to test your code at the moment, so I might be missing something small, but at a glance, this appears like it should do what you're looking to do.

I fixed it now.


Although now I have a question with the same program.
"For every one hundred iterations the program should ask the user if they want to continue."
Is there a way I can automate this, or do I have to do a separate if statement for multiple multiples (heh) of 100
Author:  Dreadnought [ Fri Mar 06, 2015 10:47 am ]
Post subject:  Re: Program is stuck at "Executing."
There is a way you can automate this. rem and mod may be helpful, but are not necessary to accomplish what you are trying to do.

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