Can you find the error in this code that aims to sum the digits of a string?

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I wrote this code in order to sum the digits of any string, and to also create a loop that stops the summing process when the length of the sum is equal to a single digit.
What's wrong?
n = '12361927'
function d = sumdigits(n)
s=0
for i=1:length(n)
s=s+str2double(n(i))
end
end
s=sumdigits(n)
if length(str2num(s))==1
s=s
else
while length(str2num(s))~=1
if length(str2num(s))==1
break
else
s=sumdigits(s)
end
end
end

Accepted Answer

Stephen23
Stephen23 on 6 Jan 2019
Simpler:
str = '12361927'
while numel(str)>1
num = sum(str-'0')
str = num2str(num)
end
Prints this in the command window:
str = 12361927
num = 31
str = 31
num = 4
str = 4
  3 Comments
Stephen23
Stephen23 on 6 Jan 2019
Edited: Stephen23 on 6 Jan 2019
str-'0'
subtracts the character code for '0' (which is 48) from the character codes of the character array str. If all of the characters in str are digits then it converts the chracter representation of those digits into their numeric values, e.g.:
>> '1234'-'0'
ans =
1 2 3 4

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More Answers (1)

Stephan
Stephan on 6 Jan 2019
Hi,
try :
n = '12361927'
s=num2str(sumdigits(n))
if strlength(s)==1
s=s;
disp('here')
else
while strlength(s)~=1
if strlength(s)==1
break
else
s=num2str(sumdigits(s))
end
end
end
function d = sumdigits(n)
s=0;
for i=1:length(n)
s=s+str2double(n(i));
end
d=s;
end

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