搜尋registry檢查可用的com port

編譯器：Dev-C++

由 msdn 的範例改編而來

#include <windows.h>
#include <stdio.h>
#include <tchar.h>

#define MAX_KEY_LENGTH 255
#define MAX_VALUE_NAME 16383
 
void QueryKey(HKEY hKey) 
{ 
    TCHAR    achKey[MAX_KEY_LENGTH];   // buffer for subkey name
    DWORD    cbName;                   // size of name string 
    TCHAR    achClass[MAX_PATH] = TEXT("");  // buffer for class name 
    DWORD    cchClassName = MAX_PATH;  // size of class string 
    DWORD    cSubKeys=0;               // number of subkeys 
    DWORD    cbMaxSubKey;              // longest subkey size 
    DWORD    cchMaxClass;              // longest class string 
    DWORD    cValues=0;              // number of values for key 
    DWORD    cchMaxValue;          // longest value name 
    DWORD    cbMaxValueData;       // longest value data 
    DWORD    cbSecurityDescriptor; // size of security descriptor 
    FILETIME ftLastWriteTime;      // last write time 
 
    DWORD i, retCode; 
 
    TCHAR  achValue[MAX_VALUE_NAME]; 
    DWORD cchValue = MAX_VALUE_NAME; 
 
    // Get the class name and the value count. 
    retCode = RegQueryInfoKey(
        hKey,                    // key handle 
        achClass,                // buffer for class name 
        &cchClassName,           // size of class string 
        NULL,                    // reserved 
        &cSubKeys,               // number of subkeys 
        &cbMaxSubKey,            // longest subkey size 
        &cchMaxClass,            // longest class string 
        &cValues,                // number of values for this key 
        &cchMaxValue,            // longest value name 
        &cbMaxValueData,         // longest value data 
        &cbSecurityDescriptor,   // security descriptor 
        &ftLastWriteTime);       // last write time 
 
    if (cValues) 
    {
        printf( "\nNumber of values: %d\n", cValues);

        for (i=0, retCode=ERROR_SUCCESS; i<cValues; i++) 
        { 
            DWORD a = 40;
            DWORD cType = REG_SZ;
            cchValue = MAX_VALUE_NAME; 
            achValue[0] = '\0'; 
            BYTE *pData = new BYTE[40];
            
            retCode = RegEnumValue(hKey,i, 
                achValue, 
                &cchValue, 
                NULL, 
                &cType,
                pData,
                &a);
 
            if (retCode == ERROR_SUCCESS ) 
            { 
                _tprintf(TEXT("(%d) %s %s\n"), i+1, achValue, pData); 
            } 
        }
    }
}

int __cdecl _tmain(void)
{
   HKEY hTestKey, hKey;

   if( RegOpenKeyEx( HKEY_LOCAL_MACHINE, "HARDWARE\\DEVICEMAP\\SERIALCOMM", 0, KEY_READ, &hTestKey) == ERROR_SUCCESS )
       //if( RegOpenKeyEx( hTestKey, "SERIALCOMM", 0, KEY_READ, &hKey) == ERROR_SUCCESS )
              QueryKey(hTestKey);

   
   RegCloseKey(hKey);
   RegCloseKey(hTestKey);
   system("PAUSE");
   return 1;
}