Input of linebreak into sprintf?

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Andreas Dorner
Andreas Dorner 2019-5-6
评论： Steven Lord 2019-5-6
Hello,
i want to input a linebreak ( via '\n' ) into a string. I mean something like this:
a =sprintf('A%sA', '\n');
%this produces
a =
A\nA
%but i want it to produce
a =
A
A
How would I do that?
/edit: this is a minimal example just to show my point, of course. The case i want to work with has multiple inputs and a more complex formatSpec..

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Jan
Jan 2019-5-6
编辑：Jan 2019-5-6
a = sprintf('A\nA')
% Or
a = sprintf('A%cA', char(10)) % %s would work also
% Use |newline| instead of char(10) in modern Matlab versions
Your code is the correct method to insert tha characters '\n' directly:
a = sprintf('A%sA', '\n');
% Equivalent to:
a = sprintf('A\\nA');
This is useful, if a file name is printed with path, because this is not reliable:
sprintf(['File: ', filename, '\n'])
If filename contains a control character as \n, \t, \c or e.g. a %s, the output will be confusing. The same must be considered for warnings and errors:
error(['Failing: ', filename])
A clean way without danger of confusing output:
error('Failing: %s', filename)
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Jan
Jan 2019-5-6
编辑：Jan 2019-5-6
@Andreas: The rules are:
  • In the format specifier of sprintf and fprintf the \ means, that the following character is treated as control. Examples: \n \r \t \a \b \10
  • To include a \ as character in a format specifier, use \\
  • Anywhere else in a string or char vector, a \ is simply \
So to include a line break (which is CHAR(10)), either include \n in the format specifier, or a char(10) in the string or char vector. So these commands produce the same results:
a = char(10)
b = sprintf('\n')
isequal(a,b) % Yes!
a = ['Line1', char(10), 'Line2']
b = sprintf('Line1\nLine2')
c = sprintf('%s\n%s', 'Line1', 'Line2')
d = sprintf('%s%c%s', 'Line1', char(10), 'Line2')
isequal(a, b, c, d) % Yes
Clear now?
Steven Lord
Steven Lord 2019-5-6
I want to increase the visiblity of one suggestion Jan made earlier in a comment in the original answer. if you're using release R2016b or later, I recommend using newline instead of char(10). IMO this makes the code author's intent very clear and avoids "magic numbers".
A = ['Line 1', newline, 'Line 2']
Note however that A is still a row vector even though it is displayed like it had two rows.
>> isrow(A)
ans =
logical
1

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