Counting number of certain letters

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Student 2018-3-18

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评论： Walter Roberson 2020-5-17

I'm trying to make a code that will output the number of a's and e's in my name. I have a basic understanding that I need to go through each element of the string and test if it's an 'a' or 'e' then add up each time. What am I doing wrong below?

myname = "jonathan"
  A = char(myname)
  numA=0;
  numE=0;
  for i=1:1:length(A)
      if i == 'a'
          numA = numA+1
      end    
      if i == 'e'
          numE = numE+1
      end    
  end    
  disp('The number of As: ');
  disp(numA);
  disp('The number of Es: ');
  disp(numE);

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Answer 1

per isakson 2018-3-18

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编辑：per isakson 2018-3-18

在 MATLAB Online 中打开

"What am I doing wrong below?"

"to go through each element of the string" your for-loop is fine
"test if it's an 'a' or 'e' then add up each time" your tests don't test what you want them to test

The loop-counter, i, takes the numerical values 1,2,3,... You test whether this numerical value is equal to a character value. That smells. However, Matlab "thinks" that you want to compare the numerical value to the "ascii-value" of the character, e.g.

>> 97=='a'
ans =
     1

Here 1 stands for true

Replace

i == 'a'

by

A(i) == 'a'

to compare the i:th character of A to the character, 'a'

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Answer 2

Image Analyst 2018-3-18

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Why not just take the histogram?

myname = 'jonathan'
% Convert to numbers:
myname = lower(myname) - '0' - 48
% Take the histogram.
edges = 1:26;
counts = histcounts(myname, edges)
% counts(1) is the number of "a"s in the word.
% counts(26) is the number of "z"s in the word.