Function to capitalize first letter in each word in string but forces all other letters to be lowercase

Does anyone know how to create a function which accepts a string and capitalizes the first letter in each word of the string, but also forces the other letters to be lowercase?

Any advice would be greatly appreciated!!

This is my attempt so far:

    str=['this is a TEST'];
    for i=1:length(str);
        if str(1,i(1));
            str= upper(str);
        else str(1,i); 
            str= lower(str);

        end
    end

[Azzi Abdelmalek]

Olivia commented

Thanks for your help! I ran it and it worked :), however I need to be able to do this as a function! Any ideas? I'm still really new to coding!

Thanks again,

Olivia

[Azzi Abdelmalek]

Olivia commented

That works! Thank you for your help! Could you please tell me how it works exactly? I understand that the string is set to lowercase and then the first letters of each word are indexed but I am not sure exactly how:

idx=regexp([' ' str],'(?<=\s+)\S','start')-1;

Thanks again :)

Olivia

[Azzi Abdelmalek]

Olivia, to add a comment, click on [comment on this answer] under an answer of your choice

[Olivia]

Thank you very much for the help!!

[Adoniram]

thanks!

Answer 1

[Azzi Abdelmalek]

str='this is a tEST';
str=lower(str)
idx=regexp([' ' str],'(?<=\s+)\S','start')-1
str(idx)=upper(str(idx))

[Azzi Abdelmalek]

function strout=uplow(str)
str=lower(str)
idx=regexp([' ' str],'(?<=\s+)\S','start')-1
str(idx)=upper(str(idx))

Then call the function

str='this is a tEST';
strout=uplow(str)

[Azzi Abdelmalek]

'(?<=\s+) means all words beginning with white space

\S' , means flowed with any non white space character

'start')-1; gives the index of the beginning of each word, I added -1 because I've used [' ' str];

[Nayeb Hasin]

what if this was the input '99this is a TEST'?

[Image Analyst]

@Nayeb Hasin Just try it:

str='99this is a TEST';
strout=uplow(str)

str = '99this is a test'

idx = 1×4

1 8 11 13

str = '99this Is A Test'

Output argument "strout" (and possibly others) not assigned a value in the execution with "solution>uplow" function.

function strout=uplow(str)
str=lower(str)
idx=regexp([' ' str],'(?<=\s+)\S','start')-1
str(idx)=upper(str(idx))
end

I guess that error is not what you expected or wanted.

Try changing strout on the function line to str.

Answer 2

[Image Analyst]

If you want something a lot more intuitive and a lot simpler than regexp, you can use allwords(). I use allwords all the time - it's a very useful utility.

Get allwords() here: http://www.mathworks.com/matlabcentral/fileexchange/27184-allwords

s='this iS the iNpUt StrinG'
individualWords = allwords(s) % Get the words separated individually.
% Capitalize the first letters
new_s = '';
for k = 1 : length(individualWords)
  % Get the kth word.
  thisWord = individualWords{k}
  % Capitalize the first letter.  Lower the subsequent letters.
  capWord = [upper(thisWord(1)), lower(thisWord(2:end))]
  % Concatenate to the new string.
  new_s = [new_s, ' ', capWord]
end
message = sprintf('This is the new string: %s', new_s);
uiwait(helpdlg(message));

You'll probably find this code a lot easier to understand than if you use regexp - I know I do. Not as compact though.

[Image Analyst]

Now you can use strsplit() to split apart a sentence into individual words.

s='this iS the iNpUt StrinG'

s = 'this iS the iNpUt StrinG'

individualWords = strsplit(s) % Get the words separated individually.

individualWords = 1x5 cell array
    {'this'}    {'iS'}    {'the'}    {'iNpUt'}    {'StrinG'}

% Capitalize the first letters
new_s = '';
for k = 1 : length(individualWords)
    % Get the kth word.
    thisWord = individualWords{k};
    % Capitalize the first letter.  Lower the subsequent letters.
    capWord = [upper(thisWord(1)), lower(thisWord(2:end))];
    % Concatenate to the new string.
    new_s = [new_s, ' ', capWord];
end
new_s = strtrim(new_s); % Get rid of leading space.
fprintf('Here is the new, output string:\n%s', new_s);

Here is the new, output string:
This Is The Input String

Answer 3

[per isakson]

The help on regexprep (R2013a) includes this example

    str = 'here are two sentences. neither is capitalized.';
    expression = '(^|\.)\s*.';
    replace = '${upper($0)}';

    newStr = regexprep(str,expression,replace)

Try

    str = ['this is a TEST']; 
    str = lower( str );
    expression = '(^|\.)\s*.';
    replace = '${upper($0)}';

    newStr = regexprep(str,expression,replace)

However, every word should be capitalized. Change expression to include characters after space

    expression = '(^|[\. ])\s*.';

[Stephen23]

This can be used in a nice one-line solution:

>> str = 'thIs IS a tEST StRiNg! wITH TWO sEntences.';
>> regexprep(lower(str),'(\<[a-z])','${upper($1)}')
ans =
This Is A Test String! With Two Sentences.

[Raghu Jagannathan]

Hi Stephen,

This is great! Can you help me understand how '${upper($1)}' works?

Thanks

[goc3]

Thanks for this, @Stephen23.

[Stephen23]

@goc3: strictly speaking [a-z] only matches Latin letters without diacritics, not every letter that can be capitalised (Latin with diacritics, Greek, Cyrillic, ...). What is the canonical MATLAB regular expression to match lower-case (or upper case) characters? Here an example using České dráhy:

T = 'české dráhy';
regexprep(lower(T),'(\<[a-z])','${upper($1)}') % fails

ans = 'české Dráhy'

X = char(0:65535);
Y = X(isstrprop(X,'lower'))

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regexprep(lower(T),sprintf('(\\<[%s])',Y),'${upper($1)}') % works

ans = 'České Dráhy'

[goc3]

@Stephen23: are you referring to \w? That also matches the underscore and digits, though it does work in this case.

Latin-only letters are sufficient for my purposes.

I thought I would ask the AI Chat Playground if it could come up with a solution. Its first attempt used the title() function, which obviously does NOT work. I told it that its "solution" created a figure and to attempt it again, after which it provided another "solution" that did not work. I again told it that what it provided did not work, after which it gave me the regexprep solution you provided above, though without the lower() part to ensure all non-first letters are not capitalized.

I also checked the functions listing for the Text Analytics toolbox; as far as I can tell, it does not have a built-in function to apply title case.

[Stephen23]

"are you referring to \w?"

No. But I am curious, how are you using it to achieve the task the OP asked about?

[goc3]

@Stephen23: In my case, all the letters are already lowercase and are only from the set [a-zA-Z_0-9].

If I were writing a utility function, the more comprehensive solution you provided in the more-recent comment would be preferred.