Problem 568. Number of 1s in a binary string
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Thats the question:
Find the number of 1s in the given binary string. Example. If the input string is '1100101', the output is 4. If the input string is '0000', the output is 0
I wrote this code, but I don't understand, what is wrong with it.
function y = one(x)
y = length(find(x))
end
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Accepted Answer
Les Beckham
on 8 Sep 2023
The find() function returns the index of all non-zero elements in the input. ASCII characters (like '0' and '1') are all non-zero (numerically) so your function will just return the length of the input string.
Example:
find('1011010')
length(find('1011010'))
There are a lot of ways to solve this problem. Look at this documentation page for one way: find characters
3 Comments
Les Beckham
on 8 Sep 2023
Mathworks has several other tutorials in addition to the Onramp.
Check this page that lists some more: Self-Paced Online Courses
More Answers (1)
Harald
on 8 Sep 2023
Hi,
find is intended for numerical non-0 elements rather than non-'0'. Instead, I would use == to compare to '0', and I would also use sum or nnz rather than length.
Best wishes,
Harald
6 Comments
Dyuman Joshi
on 8 Sep 2023
"and it didn't work."
Because you are comparing with a numerical value
x='1011010';
x==1
What you want to do is compare with a character
x=='1'
"And why can't I only use sum(x)?"
Because that will give the sum of the values of x, which is not what the questions asks for.
What you want is, the total number of values i.e. sum where x isequal to '1'. So that's what is done.
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