How do I include zeros when converting from an integer to a string?

I have a script which reads information from an XML file and converts that information into strings for later use. Here is the part I'm interested in.

function patientID = getPatientID(td)
% getPatientID(td)
% 
% patientID = getPatientID(td)
% 
% Extracts the patient id for a tSeries-obj. Can accept arrays of
% tSeries objects or single tSeries
% 
%INPUTS:
% td   - a tSeries object containing the timeseries data to be analyzed.
% 
%OUTPUTS:
% patientID - the patient ID for a tSeries-obj : string
% 
% BATeplitzky July 1, 2014

% size input array of tSeries objects
sz = builtin('size',td); % size of td
patientID = cell(sz);

td_vec = td(:); % matix to vector
nDFN = length(td_vec); % number of tSeries-objs

% get PatientID of each object
patientID_vec = cell(nDFN,1); % preallocate
for iDFN = 1:nDFN % for each file
    try
        patientID_vec{iDFN} = td_vec(iDFN).DataInfo.UserData.RecordingItem.PatientID;
    catch
        patientID_vec{iDFN} = 'NoData';
    end
end

% output to match input array of tSeries objects
patientID(:) = patientID_vec;

% make sure the patient ID is a string
patientID = cellfun(@num2str,patientID,'UniformOutput',0);

The code works fine except when the XML file has a number such as "001234", the main program (not shown here for security reasons) reads it as "1234".

Answer 1

[the cyclist]

Replace your last line with this:

patientID = cellfun(@(x)sprintf('%06d',x),patientID,'UniformOutput',0)

[DeeWBee]

Works perfectly! Thanks!

Answer 2

[Azzi Abdelmalek]

a=1234
b=sprintf('00%d',a)

[Azzi Abdelmalek]

You can save the first 0 in v1 and the result from str2num(a) in v2

a='00126'
b=regexp(a,'[^0]+')
v1=repmat('0',1,b-1)
v2=str2num(a)

Answer 3

[Star Strider]

Another possibility:

x = 1234;
Q = sprintf('%06d', x)

Q =
001234

It doesn’t add zeros, but does lead-zero-padding out to 6 places in this format. If there are six digits in ‘x’, there are no leading zeros.

[DeeWBee]

Ah okay! I understand now. Thanks!

[Star Strider]

My pleasure!