Write a function called digit_counter that takes the name of a text file as input and returns the number of digits (i.e., any of the characters, 0-to-9) that the file contains. If there is a problem opening the file, the function returns -1.

Question

Vaibhav Dwivedi 2017-10-7

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评论： Walter Roberson 2019-2-7

digit_counter.m

My code:

function[c]=digit_counter(filename)
       fid=fopen(filename,'rt');
       if fid<0
           error('error opening file %s', filename);
       end
       A = char(fread(fid,inf)).';
       c=length(A);
       fclose(fid);
       end

I am getting the error:

   Not enough input arguments.
   Error in digit_counter (line 2)
   fid=fopen(filename,'rt');

Can somebody pls help me out here.

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Walter Roberson 2017-12-28

http://www.mathworks.co.uk/matlabcentral/answers/43073-a-guide-to-tags

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Answer 1

Walter Roberson 2017-12-28

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When you ran the code, you did not pass in the name of the file that you wanted to read.

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Walter Roberson 2019-2-7

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sum(ismember(fileread(FileName), '0':'9'))

No fopen/fread needed.

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Answer 2

Image Analyst 2017-10-7

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You're not even building the histogram. See if you can finish this:

counts = zeros(1, 10); % Histogram.
fileChars = fileread('test1.m');
for k = 1 : length(fileChars)
  theInteger = str2double(fileChars(k));
  if ~isreal(theInteger)
    % isreal is used because a letter i evaluates as 1 + 1*i (complex)
    continue;
  end
  if ~isnan(theInteger)
    % Increment histogram by 1
    index = theInteger + 1; % Convert from 0-based to 1-based indexing.
    counts(index) = counts(index) + 1;
  end
end
counts

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Jan 2018-3-11

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For "any of the characters, 0-to-9" isstrprop(fileChars, 'digit') is more efficient. Or:

sum(fileChars >= '0' & fileChars <= '9')

Walter Roberson 2018-3-11

or sum(ismember(fileChars, '0':'9'))

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Answer 3

Srishti Saha 2018-3-11

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This should definitely work:

%function: digit_counter in a file; takes file name as argument
function dc = digit_counter(filename)
  dc=-1;
  fid= fopen(filename,'r');
  if fid>=0
      dc= nnz(isstrprop(fileread(filename),'digit'));
      fclose(fid);
  end
end

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Jan 2018-3-11

The question was asked on 7 Oct 2017 and I think it is no problem, that you have solved this homework now.

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Answer 4

Ranil Fernando 2018-6-3

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I'm getting a strange error to this problem.

Problem 1 (digit_counter):
    Feedback: Your function performed correctly for argument(s) 'digit_counter.m'
    Feedback: Your function performed correctly for argument(s) 'day_counter.m'
    Feedback: Your function performed correctly for argument(s) 'smallest_multiple.m'
    Feedback: Your function performed correctly for argument(s) 'maxproduct.m'
    Feedback: Your function performed correctly for argument(s) 'number2letters.m'
    Feedback: Your function performed correctly for argument(s) 'circular_primes.m'
    Feedback: Your function performed correctly for argument(s) 'cyclotron.m'
    Feedback: Your function performed correctly for argument(s) 'huge_add.m'
    Feedback: Your program made an error for argument(s) 'Non-existent file. This should generate an error'
      Your solution is _not_ correct.

and my code is;

function digi_num = digit_counter(filename)
digi_num = 0;
str_len = [];
digi_ch = {'0','1','2','3','4','5','6','7','8','9'};
fid = fopen(filename,'rt');
if fid < 0
    digi_num = -1;
end
str_line = fgets(fid); %read file as string
while ischar(str_line)
    str_len = length(str_line);
    for ii = 1:str_len
        for jj = 1:10
            if str_line(ii)==digi_ch{jj}
                digi_num = digi_num + 1;
            end
        end
    end
    str_line = fgets(fid);
end

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Walter Roberson 2018-6-3

In the case where the open fails, you are still trying to proceed and fgets(fid) even though fid is not valid.

Ranil Fernando 2018-6-3

Thanks for the prompt feedback @Walter. Replacing 'end' statement with an 'else' after the if statement solved the issue.

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Answer 5

RAMAKANT SHAKYA 2019-2-7

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function d=digit_counter(filename)
fid=fopen(filename,'r');
       if fid<0
           d=-1;
       else
       A = char(fread(fid,inf))';% reading all data from the text file
       
             k=isstrprop(A,'digit');  %determines if elements of input text are of the specified category,  numbers
                d= nnz(k);% Number of nonzero matrix elements.
                fclose(fid);
       end
end