What's wrong with this problem!!

used y=y+str2double(x(i)) instead of y=y+str2double(x(i)) and it worked just fine

function y = one(x)
y1=[];
for a=x(1:end)
y1 = [y1,str2num(a)];
end
y=sum(y1);
end

y=0;
for index=1:length(x)
y = y + str2num(x(index));
end

y = sum(x=='1');

Well, well! Here he/she is as well, great job continuing your copy and paste of the cheap and meaningless trick you prick!

In case you didn't know how to do it and wanted to know how -which somehow I doubt it for some reason!, but anyhow, here is one of MANY ways to do it:
function x=one(x),x=count(x,'1');end

Why doesn't this solution work? Works just fine in my desktop program...

Because you compare a char Array to a double. Try (x=='1').