How can I get the first and last letters out of each word?

This is how I write the function. Basically, if you input sentence "Check adjacent elements 4speical pat-terns", it gives you {'CHECK', 'ADJACENT', ELEMENTS', 'SPECIAL', 'PAT', 'TERNS'}. The question is I tried to give the word = str(beginning letter : ending letter), but the check condition went wrong when it comes to the first letter of the setence (eg. C in check). I don't know how to fix it.

function ca = makeKeyArray(str)

char=isletter(str);

for k=1:length(str)
    if strcmp(str(k),'''')==1 || char(k)==1   %set condition
       char(k)=1;
    end
end

count=0;
for i=1:length(str)-1
    if char(i-1)==0 && char(i)==1   %find first letter in word, this is where it goes wrong
        count=count+1;
        beg(count)= i;
    elseif char(i+1)==0 && char(i)==1   %find last letter in word
        count=count+1;
        close(count)=i;
        word(count)=str(beg(count):close(count));  %get word. e.g. word(1) = str(beg(1):close(1)) = str(1:6)
    end
end
ca=upper(word);

end

Answer 1

[Bruno Luong]

Fix few things in your code

function ca = makeKeyArray(str)
char=isletter(str);
for k=1:length(str)
    if strcmp(str(k),'''')==1 || char(k)==1   %set condition
       char(k)=1;
    end
end
count=0;
for i=1:length(str) % FIX HERE
    if i==1 || char(i-1)==0 && char(i)==1   % FIX HERE
        count=count+1;
        beg(count)= i;
    elseif i==length(str) || char(i+1)==0 && char(i)==1   % FIX HERE
        %count=count+1;  % FIX HERE
        close(count)=i;
        word{count}=str(beg(count):close(count));  % curly bracket
    end
end
ca=upper(word);
end

Test

>> makeKeyArray('Check adjacent elements 4speical pat-terns')

ans =

  1×6 cell array

    {'CHECK'}    {'ADJACENT'}    {'ELEMENTS'}    {'SPEICAL'}    {'PAT'}    {'TERNS'}

[Aimee Jin]

Thank you so much for the help! I didn't think of it (i==1 and i==length(str) )!

Also the deletion of "count = count +1" for the last letter is of great help.

Answer 2

[Ameer Hamza]

You can just use regexp()

str = 'Check adjacent elements 4speical pat-terns';
out = regexp(str, '[A-Za-z]*', 'match')

Result

>> out
out =
  1×6 cell array
    {'Check'}    {'adjacent'}    {'elements'}    {'speical'}    {'pat'}    {'terns'}

[Aimee Jin]

we can't actually use this function. So this is why I want to find the first letter and last letter of a word.

[Ameer Hamza]

Are you required to use a for-loop? In that case, the easiest solution will be to convert this regular expression into a state-diagram, which will then be much easier to code.

[Aimee Jin]

We don't have to use for-loop. But the main functions we can use are "for", "while", "if", "isletter", "isspace", "strcmp", "upper", "num2str".

[Rik]

The best solution by far is to use a regular expression. Failing that, you can use isletter to determine the location of letters. Then you need find a way to separate the runs of trues.