fprintf

Writes data to a file.

Syntax

• fprintf(format, v1, ... , vn)

• fprintf(fid, format, v1, ... , vn)

• R = fprintf(fid, format, v1, ... , vn)

Input argument

• fid - a file descriptor

• format - a string describing the format to used_function.

• v1, ... , vn - data to convert and print according to the previous format parameter.

Output argument

• R - an integer value: number of bytes that fprintf write.

Description

Write data in text form to the file specified by the file descriptor fid.

characters encoding uses fopen parameter.

If fid equals 1 redirection in stdout.

If fid equals 2 redirection in stderr.

The format follows C fprintf syntax.

Value type	format	comment
Integer	%i	base 10
Integer signed	%d	base 10
Integer unsigned	%u	base 10
Integer	%o	Octal (base 8)
Integer	%x	Hexadecimal (lowercase)
Integer	%X	Hexadecimal (uppercase)
Floating-point number	%f	Fixed-point notation
Floating-point number	%e	Exponential notation (lowercase)
Floating-point number	%E	Exponential notation (uppercase)
Floating-point number	%g	Exponential notation (compact format, lowercase)
Floating-point number	%G	Exponential notation (compact format, uppercase)
Character	%c	Single character
String	%s	Character vector.

To display a percent sign, you need to use a double percent sign (%%) in the format string.

Examples

fileID = fopen([tempdir(), 'fprintf.txt'],'wt');
fprintf(fileID, 'an example of %s.', 'text');
fclose(fileID);

R = fileread([tempdir(), 'fprintf.txt'])

fprintf(1, 'an value %g.', pi);
fprintf(2, "an value %g.", pi);

How to use backspace

reverseStr = '';
for idx = 1 : 100
 percentDone = idx;
 msg = sprintf('Percent done: %3.1f', percentDone);
 fprintf([reverseStr, msg]);
 reverseStr = repmat(sprintf('\b'), 1, length(msg));
end

Display a percent sign

fprintf(1, '%d%%.', 95)

See also

fopen, fclose, fread.

History

Version	Description
1.0.0	initial version

Author

Allan CORNET