Passing formatted string output of sprintf to fprintf

I have a writeToLog function which takes formatted string and uses fprintf to print the formated string to both a log file and to a command window.

When I use fprintf to print a file location by passing file directory directly, it works perfectly:

dir = '\\file_server\parent_dir\sub_dir';
fprintf('Saving the log file to: %s\n', dir))

However, when I pass the formated string output of sprintf to fprintf, it errors out:

format_str = sprintf('Saving the log file to: %s\n', dir)

>> fprintf(format_str)
Warning: Escaped character '\p' is not valid. See 'doc sprintf' for supported special characters. 
Saving the log file to: \file_server>> 

Is there a way for fprintf to print the formatted string as is?

[Hank]

Since the string is already formatted, just use

disp(formated_str)

[Louis]

Thanks for the suggestions.

I have a helper function

function writeToLog(fid, formatted_str)
    % print to log file
    fprintf(fid, formatted_str);
    % print to command window
    fprintf(formatted_str);
end

And the purpose of this function is to write information to both the command window and a log file.

Since I wanted to keep this function just take the file id and the formatted string, every where in my code I have

formatted_str = sprintf(...);
writeToLog(fid, formatted_str);

Not sure display alone will help me to write to both the command window and the log file.

Any suggestions?

Answer 1

[Image Analyst]

You'll need to do

function writeToLog(fid, formatted_str)
    % Write to log file.
    fprintf(fid, '%s\n', formatted_str);
    % Print to command window.
    fprintf('%s\n', formatted_str);
end

[Louis]

Thank you!

Answer 2

[Steven Lord]

format_str = sprintf('Saving the log file to: %s\n', dir)

>> fprintf('%s', format_str)

You don't want to use the string created by sprintf as the format specifier, you want to use it as data with the '%s' format specifier.

BTW, you may want to use a different variable name to contain the name of your directory. dir already has a meaning in MATLAB.

[Louis]

I have a helper function

function writeToLog(fid, formatted_str)
    % print to log file
    fprintf(fid, formatted_str);
    % print to command window
    fprintf(formatted_str);
end

And the purpose of this function is to write information to both the command window and a log file.

Since I wanted to keep this function just take the file id and the formatted string, every where in my code I have

formatted_str = sprintf(...);
writeToLog(fid, formatted_str);

Any suggestions?

[Steven Lord]

If the second input to writeToLog has always passed through sprintf, it's always going to be text (either a char or string array.) So tell fprintf that just like Image Analyst suggested.

[Louis]

Thank you!