MATLAB: Sprintf format specifiers won’t print newline

Question

I'm trying to create a string that has a newline in it. My problem is with sprintf. I'm trying to put a newline (\n) character in my string, and it's behaviour is very strange… sometimes sprintf returns an empty string, and sometimes it just prints '\n' as part of the text. I want it to actually insert a line.

This is sort of what my string looks like, but with some variables inserted between the angle brackets:

 entry = '% * < >\n';

I tried going straight ahead with sprintf:

 sprintf(entry)

This produces

 Empty string: 1-by-0

I tried accounting for the newline:

 sprintf('\n', entry)

This seems to produce just a newline. I then thought maybe the percent sign was special, so I tried the 'escape character' syntax which is mentioned on the sprintf reference page but not really explained:

 sprintf('%%', entry)

This produces just a percent sign. Next I tried using the string specifier %s. I found that

 sprintf('%s', entry)

produced

 % * < >\n

and that

 sprintf('%s\n', entry)

produced the same thing but with a newline after the string, but not where my actually '\n' is. Whenever I add '%%' in there, it just prints out a percent sign. Can anyone tell me what I'm doing wrong? This is puzzling because simply doing sprintf(string) works for me with other strings that have newlines in them.

Answer 1

It turns out that '%' needs to be written as '%%' in the string (thank you Honglei Chen), and that was somehow interfering with my newline working as well. In the end I used

 entry = sprintf('%%* < >\n');

which produces

 % * < >

plus a newline. If you use '%s', I guess it interprets every character as itself:

 entry = sprintf('%s', '%%* < >\n');
 ans =
 %%* < >\n