'dim': identifier not found - c++

Question

I am getting this error message:
error C3861: 'dim': identifier not found
Here are my includes:
#include "stdafx.h"
#include "HSMBTPrintX.h"
#include "HSMBTPrintXCtrl.h"
#include "HSMBTPrintXPropPage.h"
#ifdef _DEBUG
#define new DEBUG_NEW
#endif
Here is my function:
#define MSS_PORTS_BASE _T("Software\\Microsoft\\Bluetooth\\Serial\\Ports")
bool FindBluetoothPort(TCHAR name[16]) {
HKEY hKey, hRoot;
TCHAR szPort[20] = _T(""), szPortString[20];
DWORD len, dwIndex=0;
bool bFound=false;
INT i = 0, rc;
DWORD dwNSize;
DWORD dwCSize;
TCHAR szClass[256];
TCHAR szName[MAX_PATH];
FILETIME ft;
hRoot = HKEY_LOCAL_MACHINE;
if (RegOpenKeyEx (hRoot, MSS_PORTS_BASE, 0, 0, &hKey) != ERROR_SUCCESS) {
rc = GetLastError();
return 0;
}
dwNSize = dim(szName); <---- ~~ !! HERE IS THE LINE THAT ERRORS
dwCSize = dim(szClass); <---- HERE IS THE LINE THAT ERRORS !!
rc = RegEnumKeyEx (hKey, i, szName, &dwNSize, NULL, szClass, &dwCSize, &ft);
while (rc == ERROR_SUCCESS)
{
// how many children
TCHAR szCurrentKey[MAX_PATH];
wcscpy(szCurrentKey, MSS_PORTS_BASE);
wcscat(szCurrentKey, TEXT("\\"));
wcscat(szCurrentKey, szName);
wcscat(szCurrentKey, TEXT("\\"));
len = sizeof(szPort);
if(RegGetValue(hRoot, szCurrentKey, _T("Port"), NULL, (LPBYTE)szPort, &len)) {
wsprintf(szPortString, _T("%s:"), szPort);
bFound = true;
break;
}
dwNSize = dim(szName);
rc = RegEnumKeyEx(hKey, ++i, szName, &dwNSize, NULL, NULL, 0, &ft);
}
if(bFound)
_tcscpy(name, szPortString);
return bFound;
}
As you can see, the two lines that use this are:
dwNSize = dim(szName);
dwCSize = dim(szClass);
Why is that an error?

Answer 1

It looks like you are wanting sizeof:
dwNSize = sizeof(szName);
dwCSize = sizeof(szClass);
sizeof returns the number of bytes of the object/variable. However, I just looked at the documentation for the API RegEnumKeyEx, and it needs the number of characters. So I think it actually should divide by the size of a TCHAR (which will be 1 or 2 depending on if your are building for Unicode).
dwNSize = sizeof(szName) / sizeof(TCHAR);
dwCSize = sizeof(szClass) / sizeof(TCHAR);

Answer 2

You want sizeof.
If you originally learned dim, that was probably a macro that really calls sizeof behind the scenes.

Answer 3

I have in the past used the following macro:
#define DIM(x) (sizeof(x)/sizeof((x)[0]))
It is not provided by any of the standard includes, you have to define it for yourself.
You can also do a more modern version using a template function:
template<typename T, size_t N>
size_t dim(const T (& array)[N])
{
return N;
}