How to use dynamic arrays with PolySpace Client for C/C++?

I see the following error message during PolySpace compilation phase when I use dynamic arrays in my code:

 Verifying sample.c

 "c:\tmp\mds2\sources\sample.c", line 4: error: expression must have a constant value

           char b[a];

                  ^

 1 error detected in the compilation of "sample.c".

Answer 1

[MathWorks Support Team]

Dynamic arrays are a feature of the C99 standard (called also variable-length arrays) and they cannot be actually used with PolySpace Client for C/C++ (C language).

As a workaround, replace the declaration of the array by a declaration containing a call to malloc. For example:

 void foo(unsigned char a)

 {

 char b[a];

 }

can be replaced by :

 #include <stdlib>

 void foo(unsigned char a)

 {

 #ifndef POLYSPACE

 char b[a];

 #else

 char *b = (char *) malloc(sizeof(char) * a);

 #endif

 }

The goal of the #ifndef directive is to keep the original code when the C file is used with a compiler, and to use the malloc when the C file is analyzed with PolySpace.

Note: the compilation flag POLYSPACE should be added to the list of flags (-D option).