why do I get error "Unable to use a value of type string as an index.??"

I wrote a code but I keep getting this error:Unable to use a value of type string as an index., how is that?

%Accepts an input character array from the user and determines how 
%many times a user-specified character appears within the character array.

%{
Define variables
strA_a-string 
check_string- user-specified character 
noccur-Number of time charU appears
%}

%Get a character array
strA_a=string(input('Enter a character array: ','s'));

%Get a user-specified character within the character array
check_string=string(input('Enter a specified character to check occurence: ','s'));

%Get the number of count c coours within A
noccur=count(strA_a,check_string);

%Tell the user
fprintf('the letter %c occurs %d times in the string.\n',check_string,noccur)

Answer 1

[Walter Roberson]

You probably accidentally assigned a value to a variable named count so that count() in your code is an indexing request instead of a function call.

(Or you might have done so in the past and you had not cleared your variables since then.)

Note:

The part of the instructions about accepting an input character array could be interpreted as expecting you to write a function that takes a parameter that is type char and which is not necessarily a character vector -- for example that it might be valid for the user to pass in

M = ['hi there';
     'aminata ']

M = 2×8 char array
    'hi there'
    'aminata '

and that the counts are to be processed for that. If so, then be careful in your code:

MS = string(M)

MS = 2×1 string array
    "hi there"
    "aminata "

count(MS, "t")

ans = 2×1

1 1

Notice the result of string() of a character array is one string entry per row of the character array, and that if you count() on a string array that the result is per string entry, not total.

[Aminata camara]

Thank you so much