Use text concatenated with GUI variable in filename

I'm trying to open a file and write to it but I keep getting this error: "Error using fprintf, Invalid file identifier. Use fopen to generate a valid file identifier." I need the file name to be a text edit from a GUI (patientid) combined with the date and time.

code:

id = get(handles.patientid,'String');

filename = strcat(id,': ',datestr(now));

fileID = fopen(filename,'w');

fprintf(fileID,...);

fclose(fileID)

thanks!

Answer 1

[Azzi Abdelmalek]

The filename with : is not valid

try

id = get(handles.patientid,'String');
filename = strcat(id,datestr(now,'dd-mm-yyyy HH-MM-SS'),'.txt');
fileID = fopen(filename,'w');
fprintf(fileID,...);
fclose(fileID)