Check MATLAB code files for possible problems
checkcode( displays messages about
filename)filename that report potential problems and opportunities
for code improvement. These messages are sometimes referred to as Code Analyzer
messages. The line number in the message is a hyperlink that you can click to go
directly to that line in the Editor. The exact text of the
checkcode messages is subject to some change between
versions.
info = checkcode(___,'-struct')n-by-1 structure
array, where n is the number of messages found.
msg = checkcode(___,'-string')
If you omit the '-struct' or '-string' argument
and you specify an output argument, the default behavior is '-struct'.
[___, also returns filepaths]
= checkcode(___)filepaths,
the absolute paths to the file names. You can specify filepaths with
either the '-struct' or '-string' options.
Run checkcode on the example file lengthofline.m. MATLAB® displays the Code Analyzer messages for lengthofline.m in the Command Window.
checkcode('lengthofline')L 21 (C 1-9): The value assigned to variable 'nothandle' might be unused.
L 22 (C 12-15): NUMEL(x) is usually faster than PROD(SIZE(x)).
L 23 (C 5-11): The variable 'notline' appears to change size on every loop iteration. Consider preallocating for speed.
L 23 (C 44-49): Use STRCMPI(str1,str2) instead of using UPPER/LOWER in a call to STRCMP.
L 27 (C 12-15): NUMEL(x) is usually faster than PROD(SIZE(x)).
L 33 (C 13-16): The variable 'data' appears to change size on every loop iteration. Consider preallocating for speed.
L 33 (C 24-31): Use dynamic fieldnames with structures instead of GETFIELD.
L 37 (C 29): When both arguments are numeric scalars, consider replacing | with || for performance.
L 38 (C 47): When both arguments are numeric scalars, consider replacing | with || for performance.
L 39 (C 47): When both arguments are numeric scalars, consider replacing | with || for performance.
L 42 (C 13-15): The variable 'dim' appears to change size on every loop iteration. Consider preallocating for speed.
L 44 (C 13-15): The variable 'dim' appears to change size on every loop iteration. Consider preallocating for speed.
L 47 (C 52): Invalid syntax at ';'. A '(' might be missing a closing ')'.
L 47 (C 53): Invalid syntax at ')'. A '[' might be missing a closing ']'.
L 47 (C 54): Parse error at ']': usage might be invalid MATLAB syntax.
L 48 (C 17): Terminate statement with semicolon to suppress output (in functions).
L 48 (C 23): If you intend to specify expression precedence, use parentheses () instead of brackets [].
Run checkcode on the example file lengthofline.m. Include message IDs and store the results in a structure.
info = checkcode('lengthofline', '-id')
info=17×1 struct array with fields:
id
message
fix
line
column
View the values for the first message
info(1)
ans = struct with fields:
id: 'NASGU'
message: 'The value assigned to variable 'nothandle' might be unused.'
fix: 0
line: 21
column: [1 9]
Run checkcode on the example file lengthofline.m using the '-modcyc' option. MATLAB® displays the modified cyclomatic complexity of the file, followed by the Code Analyzer messages for lengthofline.m.
checkcode('lengthofline', '-modcyc')
L 1 (C 23-34): The modified cyclomatic complexity of 'lengthofline' is 12.
L 21 (C 1-9): The value assigned to variable 'nothandle' might be unused.
L 22 (C 12-15): NUMEL(x) is usually faster than PROD(SIZE(x)).
L 23 (C 5-11): The variable 'notline' appears to change size on every loop iteration. Consider preallocating for speed.
L 23 (C 44-49): Use STRCMPI(str1,str2) instead of using UPPER/LOWER in a call to STRCMP.
L 27 (C 12-15): NUMEL(x) is usually faster than PROD(SIZE(x)).
L 33 (C 13-16): The variable 'data' appears to change size on every loop iteration. Consider preallocating for speed.
L 33 (C 24-31): Use dynamic fieldnames with structures instead of GETFIELD.
L 37 (C 29): When both arguments are numeric scalars, consider replacing | with || for performance.
L 38 (C 47): When both arguments are numeric scalars, consider replacing | with || for performance.
L 39 (C 47): When both arguments are numeric scalars, consider replacing | with || for performance.
L 42 (C 13-15): The variable 'dim' appears to change size on every loop iteration. Consider preallocating for speed.
L 44 (C 13-15): The variable 'dim' appears to change size on every loop iteration. Consider preallocating for speed.
L 47 (C 52): Invalid syntax at ';'. A '(' might be missing a closing ')'.
L 47 (C 53): Invalid syntax at ')'. A '[' might be missing a closing ']'.
L 47 (C 54): Parse error at ']': usage might be invalid MATLAB syntax.
L 48 (C 17): Terminate statement with semicolon to suppress output (in functions).
L 48 (C 23): If you intend to specify expression precedence, use parentheses () instead of brackets [].
Suppress specific messages by creating and specifying a settings file. For example, the file lengthofline.m includes several lines that use | instead of || as the OR operator. By default, checkcode flags these lines.
checkcode('lengthofline')L 21 (C 1-9): The value assigned to variable 'nothandle' might be unused.
L 22 (C 12-15): NUMEL(x) is usually faster than PROD(SIZE(x)).
L 23 (C 5-11): The variable 'notline' appears to change size on every loop iteration. Consider preallocating for speed.
L 23 (C 44-49): Use STRCMPI(str1,str2) instead of using UPPER/LOWER in a call to STRCMP.
L 27 (C 12-15): NUMEL(x) is usually faster than PROD(SIZE(x)).
L 33 (C 13-16): The variable 'data' appears to change size on every loop iteration. Consider preallocating for speed.
L 33 (C 24-31): Use dynamic fieldnames with structures instead of GETFIELD.
L 37 (C 29): When both arguments are numeric scalars, consider replacing | with || for performance.
L 38 (C 47): When both arguments are numeric scalars, consider replacing | with || for performance.
L 39 (C 47): When both arguments are numeric scalars, consider replacing | with || for performance.
L 42 (C 13-15): The variable 'dim' appears to change size on every loop iteration. Consider preallocating for speed.
L 44 (C 13-15): The variable 'dim' appears to change size on every loop iteration. Consider preallocating for speed.
L 47 (C 52): Invalid syntax at ';'. A '(' might be missing a closing ')'.
L 47 (C 53): Invalid syntax at ')'. A '[' might be missing a closing ']'.
L 47 (C 54): Parse error at ']': usage might be invalid MATLAB syntax.
L 48 (C 17): Terminate statement with semicolon to suppress output (in functions).
L 48 (C 23): If you intend to specify expression precedence, use parentheses () instead of brackets [].
Create a settings file that suppresses the message flagging the use of | as the OR operator.
On the Home tab, in the Environment section, click the Preferences button.
Select Code Analyzer in the left pane.
Under Default Settings, in the Aesthetics and Readability section, clear the message Use instead of | as the OR operator in (scalar) conditional statements.
Enter mysettings.txt as the file name and save it to your current folder.
Press the Cancel button to exit out of the preference panel without changing the active settings.
Run checkcode on the example file using the custom settings file mysettings.txt. The message Use instead of | as the OR operator in (scalar) conditional statements is suppressed and is no longer visible in the list of messages.
checkcode('lengthofline','-config=mysettings.txt')
L 21 (C 1-9): The value assigned to variable 'nothandle' might be unused.
L 22 (C 12-15): NUMEL(x) is usually faster than PROD(SIZE(x)).
L 23 (C 5-11): The variable 'notline' appears to change size on every loop iteration. Consider preallocating for speed.
L 23 (C 44-49): Use STRCMPI(str1,str2) instead of using UPPER/LOWER in a call to STRCMP.
L 27 (C 12-15): NUMEL(x) is usually faster than PROD(SIZE(x)).
L 33 (C 13-16): The variable 'data' appears to change size on every loop iteration. Consider preallocating for speed.
L 33 (C 24-31): Use dynamic fieldnames with structures instead of GETFIELD.
L 42 (C 13-15): The variable 'dim' appears to change size on every loop iteration. Consider preallocating for speed.
L 44 (C 13-15): The variable 'dim' appears to change size on every loop iteration. Consider preallocating for speed.
L 47 (C 52): Invalid syntax at ';'. A '(' might be missing a closing ')'.
L 47 (C 53): Invalid syntax at ')'. A '[' might be missing a closing ']'.
L 47 (C 54): Parse error at ']': usage might be invalid MATLAB syntax.
L 48 (C 17): Terminate statement with semicolon to suppress output (in functions).
L 48 (C 23): If you intend to specify expression precedence, use parentheses () instead of brackets [].
filename — File nameFile name, specified as a character vector, a string array, or a cell array of character vectors. The file name can include a partial path, but must be in a folder on the search path or in the current folder.
If filename is a nonscalar string array or a cell array of character
vectors, MATLAB® displays information for each file.
Note
You cannot combine cell arrays and character arrays of file
names. For example, you cannot have {'lengthofline', 'buggy'},
'collatz' as an input.
Example: 'lengthofline'
Example: {'lengthofline', 'buggy'}
Data Types: char | string
option — Display option'-id' | '-fullpath' | '-notok' | '-cyc' | '-modcyc' | '-config'Display option, specified as one of these values. Options can appear in any order.
| Option | Description |
|---|---|
'-id' | Request the message ID, where ID is a character vector. When
returned to a structure, the output also has the id field,
which is the ID associated with the message. |
'-fullpath' | Assume that the input file names are absolute paths, so that checkcode does
not try to locate them. |
'-notok' | Run For information
on |
'-cyc' | Display the McCabe cyclomatic complexity of each function in the file. In general, lower complexity values indicate programs that are easier to understand and modify. Evidence suggests that programs with higher complexity values are more likely to contain errors. Frequently, you can lower the complexity of a function by dividing it into smaller, simpler functions. Some people advocate splitting up programs that have a complexity value over 10. |
'-modcyc' | Displays the modified cyclomatic complexity of each
function in the file. The modified cyclomatic complexity for
a function is equal to the McCabe cyclomatic complexity
except for one difference. McCabe cyclomatic complexity
counts each individual case within a
switch statement as 1, while
modified cyclomatic complexity counts the entire
switch statement as 1. In general,
switch statements are simpler than
nested if-elseif-else statements and
therefore, the modified cyclomatic complexity is often
considered a better measure of code complexity. |
| Override the default active settings file with the specified settings file. If the specified file is not in the current folder, provide the full path to the file. For information about
creating a settings file, see Save and Reuse Code Analyzer Message Settings. If you specify an invalid file,
To ignore
all settings files and use the factory default
preference settings, specify
|
info — Message informationMessage information, returned as a n-by-1 structure
array, where n is the number of messages returned
by the checkcode command. If you specify multiple
file names as input, or if you specify a cell array as input, info contains
a cell array of structures.
Field | Description |
|---|---|
| Message describing the suspicious construct that code analysis caught. |
| Vector of line numbers, indicating which lines of the file the message applies to. |
| Two-column array of columns numbers (column extents), indicating which columns of the file the message applies to. The first column of the array specifies the column in the Editor where the message begins. The second column of the array specifies the column in the Editor where the message ends. In the two-column array, each occurrence of a message has a row. |
msg — Message informationMessage information, returned as a character vector. If you
specify multiple file names as input, or if you specify a cell array
as input, msg contains a character vector where
the information for each file is separated by 10 equal sign characters,
a space, the file name, a space, and 10 equal sign characters.
Example: ========== C:\MyMatlabFiles\buggy.m ==========
filepaths — Absolute paths of filesAbsolute paths of files, specified as a cell array of character
vectors. MATLAB lists the filepaths in the
same order as the specified input files.
To force the Code Analyzer to ignore a line of code, use %#ok at
the end of the line. You can add comments after the tag.
unsuppressed1 = 10 % This line will get caught suppressed2 = 20 %#ok This line will not get caught suppressed3 = 30 %#ok This line will not get caught
You have a modified version of this example. Do you want to open this example with your edits?