strreal emulation

[chrispminis]

We all know Turing comes with a few helpful conversion commands.

strint
intstr
strreal etc.

But for one of my assignments, these are forbidden. Now one of the sub assignments for this main one is to emulate the strreal function. I have already succeeded in creating a multidigit integer converter but im stumped on decimal numbers. Here's what I have so far:

code:

var str : string var number : real := 0 var mark : int var dec : boolean := false get str for i : 1 .. length (str) %Check if theres a decimal.     if str (i) = "." then         mark := i         dec := true     end if end for for i : 1 .. length (str)     if dec = true then         if str (i) not= "." then             if i < length (str) - mark then                 number += (ord (str (* +1 - i)) - 48) * 10 ** (i - 1) %If the number is after the decimal do normal.             elsif i >= length (str) - mark then                 number += (ord (str (* +1 - i)) - 48) * 10 ** (i - 2) %If the number is before it then take off a power of 10.             end if         end if     else         number += (ord (str (* +1 - i)) - 48) * 10 ** (i - 1) %Conversion for an integer.     end if end for if dec = true then % If there was a decimal then divide the number by appropriate power of 10.     number := number / (10 ** (length (str) - mark)) end if %Check if conversion was successful and number can be properly manipulated. put " " put number put number * 2

You could either improve on this code, or write your own. Im pretty tired right now, and I'm not thinking right, and I've deviated from that code many times, sometimes getting closer but never quite there. If someone could please help. And BTW anyone at my school who stumbles across this, feel free to use it.

[Delos]

Quite the problem you have here, eh? A couple of pointers:

code:

for i : 1 .. length (str) %Check if theres a decimal.     if str (i) = "." then         mark := i         dec := true     end if end for

Could be replaced by:

code:

mark := index (str, ".") if mark > 0 then     dec := true end if

Simple, eh?

As for the rest of your code - a big problem arises in that you're assuming the string inputted will always be of a certain length or greater. If it isn't, well - you get some errors occuring in your exponents.
Let's try a different approach. Again, accept a string input of your real number. You can do a proof of it to make sure it is a valid number. Next, identify the position of the decimal (using index()), and use some string manipulation to excise it. (i.e., "5.403" would become "5403"). Convert this number to a real number, but using your integer algorithm. Finally, based upon the initial position of the decimal, divide your number by the requisite expontent of 10.

Yatta!

[Andy]

you're trying too hard...

code:

function myStrreal (s : string) : real     var noDecimal := 0     if index (s (index (s, ".") + 1 .. *), ".") > 0 then         result 31212012     end if     for i : 1 .. length (s)         if s (i) >= '0' and s (i) <= '9' then             noDecimal *= 10             noDecimal += ord (s (i)) - ord ('0')         elsif s (i) not= '.' then             result 31212012         end if     end for     result noDecimal / (10 ** (length (s) - index (s, "."))) end myStrreal put myStrreal ("12.2000")

EDIT: now its a bit longer, but has error checking. if the thing is not strreal ok, it'll output 31212012, (my pathetic attempt at writeing error in leet)

[Tony]

now for bonus points, write myStrrealok()

[jamonathin]

code:

function myStrrealok (s : string) : string     var ok : string := "false"     var counter : int := 0     for i : 1 .. length (s)         if s (i) not= "." and strintok (s (i)) then             counter += 1         elsif s (i) = "." then             counter += 1         end if     end for     if counter = length (s) then         ok := "true"     end if     result ok end myStrrealok put myStrrealok ("12.00001")

[Andy]

err wtf.. you're using strintok.. the whole point was to not use any of those functions...

code:

function myStrrealok (s : string) : bool     var hasDecimal := false     for i : 1 .. length (s)         if s (i) < '0' or s (i) > '9' or (s (i) = '.' and hasDecimal) then             result false         elsif s (i) = '.' then             hasDecimal := true         end if     end for         result true end myStrreal put myStrreal ("12.20000")

[jamonathin]

Wellz then. here's what I would do instead.

code:

function myStrrealok (s : string) : string     var ok : string := "false"     var counter : int := 0     var numbah : array 1 .. 10 of string := init ("0", "1", "2", "3", "4", "5", "6", "7", "8", "9")     for i : 1 .. length (s)         for w : 1 .. upper (numbah)             if s (i) = numbah (w) then                 counter += 1             end if         end for         if s (i) = "." then             counter += 1         end if     end for     if counter = length (s) then         ok := "true"     end if     result ok end myStrrealok put myStrrealok ("12.2311312")

However comparing string values is much easier and more efficient.

[Cervantes]

You guys are missing one very important feature:

code:

put myStrrealok ("2e3")

Should be true, but it outputs false.

[Andy]

blah blah cervantes, shush you.

jamonathin, you're trying too hard.. why use an array when you can simply use ascii values?

[jamonathin]

true true, i forgot about those. I am stumped tho on how to do what cervantes is talkin about; ("2e3"). How can you change it to int, or at least run a for loop with that 3 as a max.

[Andy]

i update my code tomorrow at work..