C / C++ / MFC

int x=1, y=5; 
x^=y^=x^=y; // whats the content of x and y now?
<a href="http://www.codeproject.com/tips/StupidXORTrick.asp" target="_blank">ClickHereForHelp();</a>

//  bInit is true for the first call
if(bInit)
{
    //  first process creates file mapping object
    //  =========================================
    hMapHandle=CreateFileMapping(INVALID_HANDLE_VALUE,NULL,PAGE_READWRITE,0,SHMEMSIZE,"XE_MEMORY_MAP");
    if(!hMapHandle)
        AfxMessageBox("CreateFileMapping failed");
}
else
{
    //  other process opens existing file mapping object
    //  ================================================
    hMapHandle=OpenFileMapping(FILE_MAP_ALL_ACCESS,FALSE,"XE_MEMORY_MAP");
    if(!hMapHandle)
        AfxMessageBox("OpenFileMapping failed");
}

//  all processes create a virtual map view
//  =======================================
lpMapAddress=MapViewOfFile(hMapHandle,FILE_MAP_ALL_ACCESS,0,0,0);
if(!lpMapAddress)
    AfxMessageBox("MapViewOfFile failed");

if(bInit)
    memset(lpMapAddress,0,SHMEMSIZE);

char buf[100];
sprintf(buf,"memory initialised: %d",bInit);
AfxMessageBox(buf);
sprintf(buf,"\tlpMapAddress=%p",lpMapAddress);
AfxMessageBox(buf);