Here is a simple code

int main()
{
    char a[10];
    a[10] = 0;
    return 0;
}

If you save that into file1.c and execute:

cppcheck file1.c

The output from cppcheck will then be:

Checking file1.c...
[file1.c:4]: (error) Array 'a[10]' index 10 out of bounds

Normally a program has many source files. And you want to check them all. Cppcheck can check all source files in a directory:

cppcheck path

If "path" is a folder then cppcheck will check all source files in this folder.

Checking path/file1.cpp...
1/2 files checked 50% done
Checking path/file2.cpp...
2/2 files checked 100% done

To exclude a file or folder, there are two options.

The first option is to only provide the paths and files you want to check.

cppcheck src/a src/b

All files under src/a and src/b are then checked.

The second option is to use -i, with it you specify files/paths to ignore. With this command no files in src/c are checked:

cppcheck -isrc/c src

The possible severities for messages are:

By default only error messages are shown. Through the --enable command more checks can be enabled.

# enable warning messages
cppcheck --enable=warning file.c

# enable performance messages
cppcheck --enable=performance file.c

# enable information messages
cppcheck --enable=information file.c

# For historical reasons, --enable=style enables warning, performance,
# portability and style messages. These are all reported as "style" when
# using the old xml format.
cppcheck --enable=style file.c

# enable warning and information messages
cppcheck --enable=warning,information file.c

# enable unusedFunction checking. This is not enabled by --enable=style
# because it doesn't work well on libraries.
cppcheck --enable=unusedFunction file.c

# enable all messages
cppcheck --enable=all

Please note that --enable=unusedFunction should only be used when the whole program is scanned. And therefore --enable=all should also only be used when the whole program is scanned. The reason is that the unusedFunction checking will warn if a function is not called. There will be noise if function calls are not seen.

cppcheck --inconclusive path

Many times you will want to save the results in a file. You can use the normal shell redirection for piping error output to a file.

cppcheck file1.c 2> err.txt

The option -j is used to specify the number of threads you want to use. For example, to use 4 threads to check the files in a folder:

cppcheck -j 4 path

Each error is reported in a <error> element. Attributes:

All locations related to an error is listed with <location> elements. The primary location is listed first.

Attributes:

You can suppress certain types of errors. The format for such a suppression is one of:

[error id]:[filename]:[line]
[error id]:[filename2]
[error id]

The error id is the id that you want to suppress. The easiest way to get it is to use the --xml command line flag. Copy and paste the id string from the XML output. This may be * to suppress all warnings (for a specified file or files).

The filename may include the wildcard characters * or ?, which match any sequence of characters or any single character respectively. It is recommended that you use "/" as path separator on all operating systems.

cppcheck --suppress=memleak:src/file1.cpp src/

// suppress memleak and exceptNew errors in the file src/file1.cpp
memleak:src/file1.cpp
exceptNew:src/file1.cpp

// suppress all uninitvar errors in all files
uninitvar

cppcheck --suppressions suppressions.txt src/

Suppressions can also be added directly in the code by adding comments that contain special keywords. Before adding such comments, consider that the code readability is sacrificed a little.

This code will normally generate an error message:

void f() {
    char arr[5];
    arr[10] = 0;
}

The output is:

# cppcheck test.c
Checking test.c...
[test.c:3]: (error) Array 'arr[5]' index 10 out of bounds

To suppress the error message, a comment can be added:

void f() {
    char arr[5];

    // cppcheck-suppress arrayIndexOutOfBounds
    arr[10] = 0;
}

Now the --inline-suppr flag can be used to suppress the warning. No error is reported when invoking cppcheck this way:

cppcheck --inline-suppr test.c

The <tokenlist> element is optional. With this element you can control what tokens are checked. The LIST can be either define, raw, normal or simple.

If there is no <tokenlist> element then simple is used automatically.

The PATTERN is the PCRE-compatible regular expression that will be executed.

The ID specify the user-defined message id.

The SEVERITY must be one of the Cppcheck severities: information, performance, portability, style, warning, or error.

Optional. The summary for the message. If no summary is given, the matching tokens is written.

Here is an example program:

void test()
{
    HPEN pen = CreatePen(PS_SOLID, 1, RGB(255,0,0));
}

The code example above has a resource leak - CreatePen() is a windows function that creates a pen. However Cppcheck doesn't assume that return values from functions must be freed. There is no error message:

# cppcheck pen1.c
Checking pen1.c...

If you provide a windows configuration file then Cppcheck detects the bug:

# cppcheck --library=windows.cfg pen1.c
Checking pen1.c...
[pen1.c:3]: (error) Resource leak: pen

Here is a minimal windows.cfg file:

<?xml version="1.0"?>
<def>
  <resource>
    <alloc>CreatePen</alloc>
    <dealloc>DeleteObject</dealloc>
  </resource>
</def>

Here is an example program:

void test()
{
    char buffer1[1024];
    char buffer2[1024];
    CopyMemory(buffer1, buffer2, 1024);
}

The bug here is that buffer2 is uninitialized. The second argument for CopyMemory needs to be initialized. However Cppcheck assumes that it is fine to pass uninitialized variables to functions:

# cppcheck uninit.c 
Checking uninit.c...

If you provide a windows configuration file then Cppcheck detects the bug:

# cppcheck --library=windows.cfg uninit.c 
Checking uninit.c...
[uninit.c:5]: (error) Uninitialized variable: buffer2

Here is the minimal windows.cfg:

<?xml version="1.0"?>
<def>
  <function name="CopyMemory">
    <arg nr="2">
      <not-uninit/>
    </arg>
  </function>
</def>

Cppcheck assumes it's ok to pass NULL pointers to functions. Here is an example program:

void test()
{
    CopyMemory(NULL, NULL, 1024);
}

The MSDN documentation is not clear if that is ok or not. But let's assume it's bad. Cppcheck assumes that it's ok to pass NULL to functions so no error is reported:

# cppcheck null.c 
Checking null.c...

If you provide a windows configuration file then Cppcheck detects the bug:

cppcheck --library=windows.cfg null.c 
Checking null.c...
[null.c:3]: (error) Null pointer dereference

Here is a minimal windows.cfg file:

<?xml version="1.0"?>
<def>
  <function name="CopyMemory">
    <arg nr="1">
      <not-null/>
    </arg>
  </function>
</def>

You can define that a function takes a format string. Example:

void test()
{
    do_something("%i %i\n", 1024);
}

No error is reported for that:

# cppcheck formatstring.c 
Checking formatstring.c...

A configuration file can be created that says that the string is a format string. For instance:

<?xml version="1.0"?>
<def>
  <function name="do_something">
    <arg nr="1">
      <formatstr/>
    </arg>
  </function>
</def>

Now Cppcheck will report an error:

cppcheck --library=test.cfg formatstring.c 
Checking formatstring.c...
[formatstring.c:3]: (error) do_something format string requires 2 parameters but only 1 is given.

The valid values can be defined. Imagine:

void test()
{
    do_something(1024);
}

No error is reported for that:

# cppcheck valuerange.c 
Checking valuerange.c...

A configuration file can be created that says that 1024 is out of bounds. For instance:

<?xml version="1.0"?>
<def>
  <function name="do_something">
    <arg nr="1">
      <valid>0-1023</valid>
    </arg>
  </function>
</def>

Now Cppcheck will report an error:

cppcheck --library=test.cfg range.c 
Checking range.c...
[range.c:3]: (error) Invalid do_something() argument nr 1. The value is 1024 but the valid values are '0-1023'.

Cppcheck doesn't assume that functions always return. Here is an example code:

void test(int x)
{
    int data, buffer[1024];
    if (x == 1)
        data = 123;
    else
        ZeroMemory(buffer, sizeof(buffer));
    buffer[0] = data;  // <- error: data is uninitialized if x is not 1
}

In theory, if ZeroMemory terminates the program then there is no bug. Cppcheck therefore reports no error:

# cppcheck noreturn.c 
Checking noreturn.c...

However if you use --check-library and --enable=information you'll get this:

# cppcheck --check-library --enable=information noreturn.c 
Checking noreturn.c...
[noreturn.c:7]: (information) --check-library: Function ZeroMemory() should have <noreturn> configuration

If a proper windows.cfg is provided, the bug is detected:

# cppcheck --library=windows.cfg noreturn.c 
Checking noreturn.c...
[noreturn.c:8]: (error) Uninitialized variable: data

Here is a minimal windows.cfg file:

<?xml version="1.0"?>
<def>
  <function name="ZeroMemory">
    <noreturn>false</noreturn>
  </function>
</def>

The proper configuration for the standard strcpy() function would be:

  <function name="strcpy">
    <leak-ignore/>
    <noreturn>false</noreturn>
    <arg nr="1">
      <not-null/>
    </arg>
    <arg nr="2">
      <not-null/>
      <not-uninit/>
    </arg>
  </function>

The <leak-ignore/> tells Cppcheck to ignore this function call in the leaks checking. Passing allocated memory to this function won't mean it will be deallocated.

The <noreturn> tells Cppcheck if this function returns or not.

The first argument that the function takes is a pointer. It must not be a null pointer, therefore <not-null> is used.

The second argument the function takes is a pointer. It must not be null. And it must point at initialized data. Using <not-null> and <not-uninit> is correct.

A Cppcheck GUI is available.

The main screen is shown immediately when the GUI is started.

Use the Check menu.

The results are shown in a list.

You can show/hide certain types of messages through the View menu.

Results can be saved to an XML file that can later be opened. See Save results to file and Open XML.

The language can be changed at any time by using the Language menu.

More settings are available in Edit → Preferences.

The project files are used to store project specific settings. These settings are:

As you can read in chapter 3 in this manual the default is that Cppcheck checks all configurations. So only provide preprocessor defines if you want to limit the checking.