Handling Strings - Help

[globSter]

I'm just taking Turing for the first time in grade 10, and we've been given an assignment to create a program that is reponsible for returning a word entered backwards.

As in, if the user was to enter:

MAN

the result would be:

NAM

however, if the user enters a palindrome such as WOW, then the output displays "This is a palindrome" on the screen.

Now, I've worked with similar programming codes before, but I'm not quite sure if I'm on the right track. I pretty new to programming so this is probably a really basic question, but any help would be greatly appreciated.

The Glob.

[Cervantes]

globSter wrote:

Now, I've worked with similar programming codes before, but I'm not quite sure if I'm on the right track.

Post what you've got and/or post your algorithm.

decreasing for loops might help you out here.

code:

for decreasing i : 10 .. 1      put i end for

[DIIST]

You need to know how to do basic string manipulation to find the word entered backwords. Do do this, this tutorial might be of some help.
http://www.compsci.ca/v2/viewtopic.php?t=8229 Once you know how to manipulate strings, the problem should seem a lot easier.

[globSter]

These are some of the codes that I've worked with ... and will post another tomorrow.

code:

put "Please enter 10 words"          for k: 1 .. 10                          get word                            line := line + word + " "        end for                              put "\nThe total number of characters in the given words are ", length(line), "."                                     avglength := length(line)/10        put "\nThese 10 words have an average word length of ",avglength, " letters."

Another program:

code:

%To display the first and last letter of a given word. put "Please enter words one to a line. End with 'quit'."                                     delay (1000)                            loop                                    put "\nPlease enter a word."        get word                            exit when word = "quit"              if length(word) >= 2 then                put word (1) ..                      put word (*)                    else                                    put "This word only has one character."     end if                          end loop

Thanks for the for decreasing loop suggestion, and I will try it. I have another program that I created using ord and chr codes. Will post tomorrow.

[Cervantes]

globSter wrote:

code:

put "Please enter 10 words"          for k: 1 .. 10                          get word                            line := line + word + " "        end for                              put "\nThe total number of characters in the given words are ", length(line), "."

This is not quite correct. The total number of characters in the given words is length (line) - 10, since you added a character (space) for each word.

[globSter]

Thankyou for the correction. I was able to solve my program problem. Thanks all for the help.

[Thuged_Out_G]

i really suck at string manipulation, and i was reading this topic ... figured id give it a try

im sure there is a much better way to do this, but heres what i came up with

code:

loop     var word : string     put "\nEnter a word to flip it(type exit to quit): "..     get word     if word = "exit" then         exit     end if     var reverse : array 1 .. length (word) of string     var right : array 1 .. length (word) of string     var count : int := 0         for i : 1 .. length (word)         reverse (i) := word (1 + length (word) - i)         right (i) := word (i)     end for     for i : 1 .. length (word)         if right (i) = reverse (i) then             count += 1             if count = length (word) then                 put "you entered a pallindrom"             end if         end if     end for     for i : 1 .. length (word)         if count not= length (word) then             put reverse (i) ..         end if     end for end loop put "Thanks for trying!"

[Cervantes]

No need to store things in an array.

code:

for i : 1 .. length (word)         if right (i) = reverse (i) then             count += 1             if count = length (word) then                 put "you entered a pallindrom"             end if         end if     end for

Two things, here. First, you only need to check up to floor(length (word) / 2). Second, the only way count could equal length (word) is if count has been incrimented each and every time. There's no point checking if count equals length (word) each time through your for loop because there is only one time in that for loop when they could possibly be equal. The value of count is not going to change, so you can easily move that if statement outside the for loop.

code:

for i : 1 .. length (word)         if count not= length (word) then             put reverse (i) ..         end if     end for

count and length (word) are fixed. There is no point comparing them each time through the loop. Move that if statement outside the loop to improve performance, and for better reasoned coding. Furthermore, if that condition was false at some point, you would miss letters from reverse. You wouldn't want that!

Here's mine:

Turing:

fcn is_palindrome (phrase : string) : boolean         var len := length (phrase)         for i : 1 .. len div 2                 if phrase (i) not= phrase (len - i + 1) then                         result false                 end if         end for         result true end is_palindrome var input_phrase : string get input_phrase put "T/F: ",input_phrase, " is a palindrome: ", is_palindrome (input_phrase)