Assignment #2



Today we are going to look at strings, for loops and if-then statements. Play around with strings and figure out what the following commands do. Notice the difference between the uses of := (assignment) and = (testing if two things are equal). I used both od and end do (these are indications of the end of a do loop). Similarly, fi and end if indicate the end of an if statement. You will want to browse the help files on strings so go to a help window and type string. The command with(StringTools); loads a bunch of functions that are helpful for working with strings. I put it at the top of the list of commands because you only need to execute it once to have those functions.

> with(StringTools); # load functions about strings
> A:="high";
> B:="five";
> C:=cat(A,B): C;
> A[3];
> B[2..3];
> C[-3];
> length(cat(B,A));
> searchtext("h",C);
> SearchAll("h",C);

> for n from 1 to length(A) do
print n,A[n];
od;

> out:="";
> for n from 1 to length(A) do
out:=cat(out,A[n],B[n]);
end do:
> out;

> out:="";
> for n from 1 to length(A) do
out:=cat(out,A[-n],B[n]);
end do:
> out;

> out:="";
> for n from 1 to length(C) do
if not IsVowel(C[n]) then
out:=cat(out,C[n]);
else
out:=cat(out,".");
fi;
od;
> out;


Question 1:

Given some string, finish with the letters of the string in reverse order. Example: if you were to start with the string w:="Wow, thats amazing!", then you should write commands which finish with the string "!gnizama staht ,woW"

Question 2:

Given a string with spaces in it like "Wow, thats amazing!", reverse the order of the words in the string so that the end result is "amazing! thats Wow,".

Question 3:

Given a string with spaces in it like "Wow, thats amazing!", reverse the order of the letters within the words in the string so that the end result is ",woW staht !gnizama".



You should open up a new worksheet and start from scratch. You will have to save your work in a file and upload that file on to the course moodle. Your solution should be a sequence of commands where it is easy to change the input string and after you execute the sequence of commands you should have the correct output string. I don't need to see your experiments with the commands that I have above, but I am interested in how far you are able to get with the three questions above.