Class: matlab.automation.streams.OutputStream
Namespace: matlab.automation.streams
Write text generated by plugin to output stream
Description
print(
writes formatted data to the output stream
,formatSpec
,A1,...,An
)stream
. The method uses the
formatSpec
formatting operators to format the data that a plugin,
such as a TestRunnerPlugin
instance, generates in arrays
A1,...,An
.
For data that is not generated by a plugin, use fprintf
to write the data to a text file or the screen, or use sprintf
to format the data into a string or character vector.
Input Arguments
stream
— Location where plugin directs text output
OutputStream
instance
Location where the plugin directs text output, specified as an
OutputStream
instance.
formatSpec
— Format of output fields
formatting operators
Format of the output fields, specified using formatting operators. formatSpec
also can include ordinary text and special characters.
If formatSpec
includes literal text representing escape characters, such as \n
, then print
translates the escape characters.
formatSpec
can be a character vector in single quotes, or a string
scalar.
Formatting Operator
A formatting operator starts with a percent sign, %
, and ends with a conversion character. The conversion character is required. Optionally, you can specify identifier, flags, field width, precision, and subtype operators between %
and the conversion character. (Spaces are invalid between operators and are shown here only for readability).
Conversion Character
This table shows conversion characters to format numeric and character data as text.
Value Type | Conversion | Details |
---|---|---|
Integer, signed |
| Base 10 |
Integer, unsigned |
| Base 10 |
| Base 8 (octal) | |
| Base 16 (hexadecimal), lowercase letters | |
| Same as | |
Floating-point number |
| Fixed-point notation (Use a precision operator to specify the number of digits after the decimal point.) |
| Exponential notation, such as | |
| Same as | |
| The more compact of | |
| The more compact of | |
Characters or strings |
| Single character |
| Character vector or string array. The type of the output text is the same as the type of |
Optional Operators
The optional identifier, flags, field width, precision, and subtype operators further define the format of the output text.
Identifier
Order for processing the function input arguments. Use the syntax
, wheren
$n
represents the positions of the other input arguments in the function call.Example:
('%3$s %2$s %1$s %2$s','A','B','C')
prints input arguments'A'
,'B'
,'C'
as follows:C B A B
.Note: If an input argument is an array, you cannot use identifiers to specify particular array elements from that input argument.
Flags
'–'
Left-justify.
Example:%-5.2f
Example:%-10s
'+'
Always print a sign character (+ or –) for any numeric value.
Example:%+5.2f
Right-justify text.
Example:%+10s
' '
Insert a space before the value.
Example:% 5.2f
'0'
Pad to field width with zeros before the value.
Example:%05.2f
'#'
Modify selected numeric conversions:
For
%o
,%x
, or%X
, print0
,0x
, or0X
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.
Example:
%#5.0f
Field Width
Minimum number of characters to print. The field width operator can be a number, or an asterisk (
*
) to refer to an input argument.When you specify
*
as the field width operator, the other input arguments must provide both a width and a value to be printed. Widths and values can be pairs of arguments or pairs within a numeric array. With*
as the field width operator, you can print different values with different widths.Example: The input arguments
('%12d',intmax)
are equivalent to('%*d',12,intmax)
.Example: The input arguments
('%*d',[2 10 5 100])
return'10 100'
, with two spaces allocated for10
and five spaces for100
. As an alternative, you also can specify the field widths and values as multiple arguments, as in('%*d',2,10,5,100)
.The function pads to field width with spaces before the value unless otherwise specified by flags.
Precision
For
%f
,%e
, or%E
Number of digits to the right of the decimal point
Example:'%.4f'
printspi
as'3.1416'
For
%g
or%G
Number of significant digits
Example:'%.4g'
printspi
as'3.142'
The precision operator can be a number, or an asterisk (
*
) to refer to an argument.When you specify
*
as the field precision operator, the other input arguments must provide both a precision and a value to be printed. Precisions and values can be pairs of arguments, or pairs within a numeric array. With*
as the precision operator, you can print different values to different precisions.When you specify
*.*
as field width and precision operators, you must specify field widths, precisions, and values as triplets.Example: The input arguments
('%.4f',pi)
are equivalent to('%.*f',4,pi)
.Example: The input arguments
('%6.4f',pi)
are equivalent to('%*.*f',6,4,pi)
.Example: The input arguments
('%*.*f',6,4,pi,9,6,exp(1))
return'3.1416 2.718282'
, with9
and6
as the field width and precision for the output ofexp(1)
.Note
If you specify a precision operator for floating-point values that exceeds the precision of the input numeric data type, the results might not match the input values to the precision you specified. The result depends on your computer hardware and operating system.
Subtypes
You can use a subtype operator to print a floating-point value as its octal, decimal, or hexadecimal value. The subtype operator immediately precedes the conversion character. This table shows the conversions that can use subtypes.
Input Value Type
Subtype and Conversion Character
Output Value Type
Floating-point number
%bx
or%bX
%bo
%bu
Double-precision hexadecimal, octal, or decimal value
Example:%bx
printspi
as400921fb54442d18
%tx
or%tX
%to
%tu
Single-precision hexadecimal, octal, or decimal value
Example:%tx
printspi
as40490fdb
Text Before or After Formatting Operators
formatSpec
can also include additional text before a percent sign,
%
, or after a conversion character. The text can be:
Ordinary text to print.
Special characters that you cannot enter as ordinary text. This table shows how to represent special characters in
formatSpec
.Special Character
Representation
Single quotation mark
''
Percent character
%%
Backslash
\\
Alarm
\a
Backspace
\b
Form feed
\f
New line
\n
Carriage return
\r
Horizontal tab
\t
Vertical tab
\v
Character whose Unicode® numeric value can be represented by the hexadecimal number,
N
\xN
Example:
returnsprint
('\x5A')'Z'
Character whose Unicode numeric value can be represented by the octal number,
N
\N
Example:
returnsprint
('\132')'Z'
Notable Behavior of Conversions with Formatting Operators
If you specify a conversion that does not fit the data, such as a text conversion for a numeric value, MATLAB® overrides the specified conversion, and uses
%e
.Example:
'%s'
convertspi
to3.141593e+00
.If you apply a text conversion (either
%c
or%s
) to integer values, MATLAB converts values that correspond to valid character codes to characters.Example:
'%s'
converts[65 66 67]
toABC
.
A1,...,An
— Data to display
arrays
Data to display, specified as numeric, character, or string arrays.
Data Types: single
| double
| int8
| int16
| int32
| int64
| uint8
| uint16
| uint32
| uint64
| logical
| char
| string
Examples
Create Custom Output Stream
In a file in your current folder, create a class named ToFigure
that redirects the plugin output to a figure and displays it in a list box within the
figure. Define the Figure
and ListBox
properties
to represent the figure and the handle to the list box, respectively.
classdef ToFigure < matlab.automation.streams.OutputStream properties(SetAccess = private) Figure end properties(Access = private) ListBox end
You must implement the print
method for any subclass of
OutputStream
. In this example, the method creates a new figure
(if necessary), formats the incoming text, and then adds it to the output stream.
methods function print(stream,formatSpec,varargin) % Create the figure if isempty(stream.Figure) || ~ishghandle(stream.Figure) stream.createFigure end newStr = sprintf(formatSpec,varargin{:}); oldStr = strjoin(stream.ListBox.String','\n'); % Create the full message fullStr = strjoin([oldStr,newStr]); fullStrArray = strsplit(fullStr,'\n','CollapseDelimiters',false); % Set the string and selection stream.ListBox.String = fullStrArray'; stream.ListBox.Value = numel(fullStrArray); drawnow end end
In a methods
block with private
access,
implement a helper method named createFigure
that creates the figure
and the list box used by the plugin.
methods(Access = private) function createFigure(stream) stream.Figure = figure(... 'Name', 'Unit Test Output',... 'WindowStyle', 'docked'); stream.ListBox = uicontrol(... 'Parent', stream.Figure,... 'Style', 'listbox',... 'String', {},... 'Units', 'normalized',... 'Position', [.05 .05 .9 .9],... 'Max', 2, ... 'FontName', 'Monospaced',... 'FontSize', 13); end end end
Save the ToFigure
class. Now, in your current folder, create a file
named ExampleTest.m
containing the following test class. The
verifyEqual
qualification in testOne
causes a
test failure. The verification in testTwo
passes. The test
corresponding to testThree
passes without producing an output.
classdef ExampleTest < matlab.unittest.TestCase methods(Test) function testOne(testCase) % Test fails testCase.verifyEqual(5,4,'Testing 5==4'); end function testTwo(testCase) % Test passes testCase.verifyEqual(5,5,'Testing 5==5'); end function testThree(testCase) % test code end end end
At the command prompt, create a test suite from the ExampleTest
class.
import matlab.unittest.TestRunner import matlab.unittest.plugins.DiagnosticsValidationPlugin suite = testsuite('ExampleTest');
Create a test runner that displays output to the command window.
runner = TestRunner.withTextOutput;
Create a DiagnosticsValidationPlugin
instance that
explicitly specifies that its output should go to a figure using the
ToFigure
output stream.
plugin = DiagnosticsValidationPlugin(ToFigure);
Add the plugin to the runner and run the tests.
runner.addPlugin(plugin) result = runner.run(suite);
Running ExampleTest ================================================================================ Verification failed in ExampleTest/testOne. ---------------- Test Diagnostic: ---------------- Testing 5==4 --------------------- Framework Diagnostic: --------------------- verifyEqual failed. --> The numeric values are not equal using "isequaln". --> Failure table: Actual Expected Error RelativeError ______ ________ _____ _____________ 5 4 1 0.25 Actual Value: 5 Expected Value: 4 ------------------ Stack Information: ------------------ In C:\work\ExampleTest.m (ExampleTest.testOne) at 4 ================================================================================ ... Done ExampleTest __________ Failure Summary: Name Failed Incomplete Reason(s) ================================================================== ExampleTest/testOne X Failed by verification.
Only the test failures produce output to the screen. By default,
TestRunner.withTextOutput
uses a DiagnosticsOutputPlugin
to display output on the screen.
In addition to the default text output being displayed on the screen, the
DiagnosticsValidationPlugin
output is directed to a docked
figure. The figure shows this text.
------------------------------ Validation of Test Diagnostic: ------------------------------ Testing 5==4 ------------------------------ Validation of Test Diagnostic: ------------------------------ Testing 5==5
The DiagnosticsValidationPlugin
displays the diagnostic information
regardless of whether the tests encounter failure conditions.
Version History
Introduced in R2014a
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