ch04.txt

#if defined (__WINDOWS__)
#   if defined LIBGDOM_STATIC
#       define GDOM_EXPORT
#   elif defined LIBGDOM_EXPORTS
#       define GDOM_EXPORT __declspec(dllexport)
#   else
#       define GDOM_EXPORT __declspec(dllimport)
#   endif
#else
#   define GDOM_EXPORT
#endif



++ Memory Checking with Valgrind

The one add-on I really recommend for C development on Linux is Valgrind. This has a number of tools, but the one I use systematically is the Memcheck tool, which catches memory leaks and illegal accesses. Here's how I run the hello program under Valgrind:

```
valgrind --tool=memcheck --leak-check=full
    --suppressions=valgrind.supp ./hello
```

Which tells me:

```
==26539== Memcheck, a memory error detector...
==26539==
Hello, World!
==26539==
==26539== HEAP SUMMARY:
==26539==     in use at exit: 0 bytes in 0 blocks
==26539==   total heap usage: 67 allocs, 67 frees,...
==26539==
==26539== All heap blocks were freed -- no leaks are possible
```

To suppress warnings from the way {{libzmq}} initializes memory, I create a file called {{valgrind.supp}} that contains:

[[code]]
{
   <socketcall_sendto>
   Memcheck:Param
   socketcall.sendto(msg)
   fun:send
   ...
}
[[/code]]

Note that running under Valgrind does slow things down. If you're expecting a certain performance from your application, don't be surprised when it crawls like a snail under Valgrind.