Length of variable is much shorter during a loop?

I have a variable 'DOYfilt' that has a sizw 1408x1 double. It contains datenums so I have a for loop to convert it to datestrings. When I enter the loop, the length of DOYfilt is only 7. What do I do so that it can go through the entire length of the variable?

for i=1:length('DOYfilt')
    date=datestr(DOYfilt(i) + datenum('2012/01/01'),'mm/dd/yyyy HH:MM');
    u10_date=[u10_date;date];
end 

[Stephen23]

length('DOYfilt')

measures the length of the character vector 'DOYfilt', which has seven characters. Probably you intended to get the lenght of the variable DOYfilt like this:

length(DOYfilt)

Answer 1

[KALYAN ACHARJYA]

This

length(DOYfilt) % Note here

Not This

length('DOYfilt')
^........'..'