Extract numbers from an integer

I want to write code that allows the user to enter a number, for example 123411 and that matlab answers with how many ones the input contains, in this case 3. Can't seem to figure this out!

Answer 1

[Jan]

This sounds like a homework question. The solution is not hard and it should be possible to solve. Unfortunately you did not post, what you have tried so far and did not ask a specific question. So how can we help you beside posting the working solution?

s  = input('Type in the number: ', 's');
n1 = sum(s == '1')

And now? Can you submit this as your solution? Does it help you to learn Matlab if I post a solution?

Read the docs for nnz for a slightly different solution. And for the next time, please post you code (even if it is not working) and ask specific questions.

[Jennifer Pettersson]

Well, you're right.. I've tried for several hours with both ismember and find but neither did work, or even be near the solution.

[Jan]

This is fine also:

sum(ismember(s, '1'))
length(find(s == '1'))
length(strfind(s, '1'))

If the number is provided numerically, use sprintf('%g') to convert it to a CHAR vector.

Answer 2

[KL]

N = 123411;
noOfOnes = nnz((dec2base(N,10) - '0')==1);

[Jennifer Pettersson]

Wow! Thanks alot!

Answer 3

[Jennifer Pettersson]

Is there any possibility to solve this with integers only? For example with mod instead? Can't seem to figure this out!

Answer 4

[Stephen23]

If you do not want to convert to string and can only perform numeric operations, then you can use mod and division in a loop:

N = 123411;
C = 0;
while N>0
  C = C+(1==mod(N,10));
  N = floor(N/10);
end

giving:

>> C
C =  3