function that ouputs the average word length in a string removing all special characters

I might be going about this all the wrong way. I need to write a function that ouputs the average word length in a string without any special characters. I think i am having trouble with the syntax and properly writing what i want to say.

function [avg] = averageLength(string)
string = 'i? love? you!'
splitString = split(string,' ');
size = size(splitString);
wordCount = size(1);
i = 1;
while 1<= wordCount
    newstring(i) = regexprep(splitString(i),'?''!''*''&''%''"''@''#''$''^''('')''1''2''3''4''5''6''7''8''9''0','');
    size(newstring(i))=strlength(newstring(i));
    for i=1:wordCount
        avg = mean(newString(i));
    end
end
end

Answer 1

[David Hill]

s = 'i? love? you!';
r=regexprep(s,'[!?"$%&#]','');%whatever special characters
m=mean(cellfun(@(x)length(x),strsplit(r,' ')))

m = 2.6667