Precompiled header support is available for Symbian OS projects that use the Nokia x86 compiler. Precompiled header files use the .pch++ extension and are only supported by emulator targets.
By default, the x86 compiler compiles the .pch++ file before compiling any .cpp files in a project.
A precompiled header file (.pch++) outputs to a new identically named file with the .mch extension. For example, HelloWorld.pch++ outputs as HelloWorld.mch. C++ source files must use the .pch++ extension.
Listing 1 shows an example of a precompiled header source file called pch_test.pch++.
#include <e32def.h>
#pragma precompile_target "pch_test.mch"
#define FOO 1
#define LATIDA 345
typedef struct foo
{
int i, j, k, l, m;
char foobar[256];
} foo;
The resultant output file, pch_test.mch can be included in other source or prefix files as:
#include pch_test.mch