How to change date in a for loop?

I am working in a for loop and inside the loop it looks as follows:

format shortg
     c=clock;
     display(c);
     c_fc = c+[0 0 0 4 0 0];   %addition for weather forecast in hours or days

       %only if 4 hour forecast is being done. change the parameters
       %(date or hours)accordingly
       if c(4)< 20;
           c_fc(4)=c_fc(4);

       else if c(4)==20;
               c_fc(4)=0;
               c_fc(3)=c_fc(3)+1;
          else if c(4)== 21;
               c_fc(4)=1;
               c_fc(3)=c_fc(3)+1;
              else if c(4)==22;
                   c_fc(4)=2;
                   c_fc(3)=c_fc(3)+1;
                  else if c(4)==23;
                       c_fc(4)=3;
                       c_fc(3)=c_fc(3)+1;
                      end
                  end
              end
           end
       end

       %making a search query for real time and forecast data
       search=sprintf('%d-%0.2d-%0.2dT%0.2d:00:00Z',c(1:4));
       search_fc=sprintf('%d-%0.2d-%0.2dT%0.02d:00:00Z',c_fc(1:4));

I need to make a search_fc which takes the values from weather website for that time period. I could update the hours and date with if and else if loop. but how can I make it shorter and also incorporate change in month and year so that my code can keep on running.

Answer 1

[Kelly Kearney]

Not quite sure I understand the question, but you can definitely simplify that code significantly. If I understand it correctly, c_fc is simply a datevector 4 hours after c, right? So then,

c = clock;
fcspan = 4/24;  % 4 hours, converted to days
c_fc = datevec(datenum(c) + fcspan);

That will take care of any complications with changing days, and you can change the forecast span and start date however you want.

[Punit Gandhi]

Thank you. yes it changes the date for c_fc. I think it will be able to change month and year automatically as well now.