函数格式：fprintf(fileID,
format, A,
...)；fprintf(format, A,
...)；count = fprintf(...)
fprintf(fileID, format,
A, ...) applies the format to
all elements of array A and any additional array
arguments in column order, and writes the data to a text file.
fprintf uses the encoding scheme specified in the call to
fopen.
fprintf(format, A, ...)
格式化数据并将其结果显示在屏幕上。
count = fprintf(...)
返回fprintf写的字节个数。
Input Arguments
|
fileID
|
One of the following:
Default: 1 (the
screen)
|
|
format
|
String in single quotation marks that describes the format of
the output fields. Can include combinations of the following:
-
Percent sign followed by a conversion character, such as
'%s' for strings.
-
Operators that describe field width, precision, and other
options.
-
Literal text to print.
-
Escape characters, including:
|
''
|
Single quotation mark
|
|
%%
|
Percent character
|
|
\\
|
Backslash
|
|
\a
|
Alarm
|
|
\b
|
Backspace
|
|
\f
|
Form feed
|
|
\n
|
New line
|
|
\r
|
Carriage return
|
|
\t
|
Horizontal tab
|
|
\v
|
Vertical tab
|
|
\xN
|
Hexadecimal number, N
|
|
\N
|
Octal number, N
|
Conversion characters and optional operators appear in the
following order (includes spaces for clarity):
![]( "MATLAB中将数据写入文本文件的函数fprintf")
The following table lists the available conversion characters
and subtypes.
| Value Type |
Conversion |
Details |
|
Integer, signed
|
%d or %i
|
Base 10 values
|
|
%ld or %li
|
64-bit base 10 values
|
|
%hd or %hi
|
16-bit base 10 values
|
|
Integer, unsigned
|
%u
|
Base 10
|
|
%o
|
Base 8 (octal)
|
|
%x
|
Base 16 (hexadecimal), lowercase letters
a–f
|
|
%X
|
Same as %x, uppercase letters A–F
|
|
%lu
%lo
%lx or %lX
|
64-bit values, base 10, 8, or 16
|
|
%hu
%ho
%hx or %hX
|
16-bit values, base 10, 8, or 16
|
|
Floating-point number
|
%f
|
Fixed-point notation
|
|
%e
|
Exponential notation, such as 3.141593e+00
|
|
%E
|
Same as %e, but uppercase, such as
3.141593E+00
|
|
%g
|
The more compact of %e or %f, with no trailing
zeros
|
|
%G
|
The more compact of %E or %f, with no trailing
zeros
|
|
%bx or %bX
%bo
%bu
|
Double-precision hexadecimal, octal, or decimal value
Example: %bx prints pi as
400921fb54442d18
|
|
%tx or %tX
%to
%tu
|
Single-precision hexadecimal, octal, or decimal value
Example: %tx prints pi as 40490fdb
|
|
Characters
|
%c
|
Single character
|
|
%s
|
String of characters
|
Additional operators include:
-
Field width
Minimum number of characters to print. Can be a number, or an
asterisk (*) to refer to an argument in the input list.
For example, the input list ('d', intmax) is equivalent to
('%*d', 12, intmax).
-
Precision
|
For %f, %e, or
%E:
|
Number of digits to the right of the decimal point.
Example: '%6.4f' prints pi as
'3.1416'
|
|
For %g or %G
|
Number of significant digits.
Example: '%6.4g' prints pi as
' 3.142'
|
Can be a number, or an asterisk (*) to refer to an
argument in the input list. For example, the input list
('%6.4f', pi) is equivalent to ('%*.*f', 6, 4,
pi).
-
Flags
|
Action
|
Flag
|
Example
|
|
Left-justify.
|
'–'
|
%-5.2f
|
|
Print sign character (+ or –).
|
'+'
|
%+5.2f
|
|
Insert a space before the value.
|
' '
|
% 5.2f
|
|
Pad with zeros.
|
'0'
|
.2f
|
|
Modify selected numeric conversions:
-
For %o, %x, or %X, print 0,
0x, or 0X prefix.
-
For %f, %e, or %E, print decimal
point even when precision is 0.
-
For %g or %G, do not remove trailing zeros or
decimal point.
|
'#'
|
%#5.0f
|
-
Identifier
Order for processing inputs. Use the syntax
n$, where n represents the
position of the value in the input list.
For example, '%3$s %2$s %1$s %2$s' prints inputs
'A', 'B', 'C' as follows: C B A
B.
The following limitations apply to conversions:
-
Numeric conversions print only the real component of complex
numbers.
-
If you apply an integer or string conversion to a numeric value
that contains a fraction, MATLAB overrides the specified
conversion, and uses %e.
-
If you apply a string conversion (%s) to integer
values, MATLAB converts values that correspond to valid character
codes to characters. For example, '%s' converts [65 66
67] to ABC.
-
Different platforms display exponential notation (such as
%e) with a different number of digits in the exponent.
|
Platform
|
Example
|
|
Windows
|
1.23e+004 |
|
UNIX
|
1.23e+04 |
-
Different platforms display negative zero (-0)
differently.
| |
Conversion Character
|
|
Platform
|
%e or %E
|
%f
|
%g or %G
|
|
Windows
|
0.000000e+000
|
0.000000
|
0
|
|
Others
|
-0.000000e+00
|
-0.000000
|
-0
|
|
|
A
|
Numeric or character array.
|
Examples
Print multiple values and literal text to the screen:
B = [8.8 7.7 ; ...
8800 7700];
fprintf('X is %4.2f meters or %8.3f mm\n', 9.9, 9900, B)
MATLAB displays:
X is 9.90 meters or 9900.000 mm
X is 8.80 meters or 8800.000 mm
X is 7.70 meters or 7700.000 mm
Explicitly convert double-precision values with fractions to
integer values, and print to the screen:
a = [1.02 3.04 5.06];
fprintf('%d\n', round(a));
Write a short table of the exponential function to a text file
called exp.txt:
x = 0:.1:1;
y = [x; exp(x)];
% open the file with write permission
fid = fopen('exp.txt', 'w');
fprintf(fid, '%6.2f .8f\n', y);
fclose(fid);
% view the contents of the file
type exp.txt
MATLAB import functions, all UNIX applications, and Microsoft
Word and WordPad recognize '\n' as a newline indicator.
However, if you plan to read the file with Microsoft Notepad, use
'\r\n' to move to a new line when writing. For example,
replace the previous call to fprintf with the
following:
fprintf(fid, '%6.2f .8f\r\n', y);
On a Windows system, convert PC-style exponential notation
(three digits in the exponent) to UNIX-style notation (two digits),
and print data to a file:
a = [0.06 0.1 5 300]
% use sprintf to convert the numeric data to text, using %e
a_str = sprintf('%e\t',a)
% use strrep to replace exponent prefix with shorter version
a_str = strrep(a_str,'e+0','e+');
a_str = strrep(a_str,'e-0','e-');
% call fprintf to print the updated text strings
fid = fopen('newfile.txt','w');
fprintf(fid, '%s', a_str);
fclose(fid);
% view the contents of the file
type newfile.txt
Display a hyperlink (The MathWorks Web Site) on the screen:
site = 'http://www.mathworks.com';
title = 'The MathWorks Web Site';
fprintf('<a href = "%s">%s</a>\n', site, title)
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(2012-03-27 08:17:57)