Number of leading zeroes as a variable

I know that to print out a number with a certain amount of leading zeroes, you are supposed to use %0X, where X is the number of digits you want in your output. For example, sprintf('%06g',13) gives you the string '000013' as output. Is there a way to make the formatting value a variable? Something along the lines of

   function x=leadzero(y,z)
       x=sprintf('%0y',z)
   end

I know it can be done with a for loop, but is there are way to implement this directly into the sprintf command?

Answer 1

[dpb]

Fer shure, just write the format string desired dynamically--

function s=leadzero(Nz,z)
   fmt=num2str(Nz,'%%0%dg');
   s=sprintf(fmt,z)
 end

Nz for "Number zeros" seemed a better variable name than y as did an s for a returned string output variable...the format string expression can be wrapped inside the sprintf call, of course, just wrote it out for clarity here.

Answer 2

[Honglei Chen]

y = 6;
z = 13;
sprintf(['%0' num2str(y) 'g'],z)