Creating a file with the same name as registry - c++

Question

I want to create a text file with the same name as a registry.
Say, I get the variable valueName, and I want it's value to be the name of a .txt file in C:\ How can I do that?
Almost final code:
void EnumerateValues(HKEY hKey, DWORD numValues)
{
for (DWORD dwIndex = 0; dwIndex < numValues; dwIndex++)
{BOOL bErrorFlag = FALSE;
char valueName[64];
DWORD valNameLen = sizeof(valueName);
DWORD dataType;
DWORD dataSize = 0;
DWORD retval = RegEnumValue(hKey, dwIndex, valueName, &valNameLen,
NULL, &dataType, NULL, &dataSize);
if (retval == ERROR_SUCCESS)
{//pregatesc calea
char* val = new char[strlen(valueName)];
sprintf(val, "C:\\%s.txt", valueName);
printf("S-a creat fisierul: %s\n", val);
//creez/suprascriu fisierul
HANDLE hFile;
hFile=CreateFile(val,GENERIC_WRITE | GENERIC_READ,FILE_SHARE_READ,
NULL, CREATE_ALWAYS , FILE_ATTRIBUTE_NORMAL,NULL);
if (hFile == INVALID_HANDLE_VALUE)
{ printf("Eroare la creat fisierul %s!\n",val);
}
//sciru in fisier
char str[] = "Example text testing WriteFile";
DWORD bytesWritten=0;
DWORD dwBytesToWrite = (DWORD)strlen(str);
bErrorFlag=WriteFile(hFile, str, dwBytesToWrite, &bytesWritten, NULL);
if (FALSE == bErrorFlag)
{
printf("Eroare la scriere in fisier\n");
}
//inchid fisierul
CloseHandle(hFile);
}
//eroare regenumv
else printf("\nError RegEnumValue");
}
}

Answer 1

The fundamental problem is that you seem to want to convert a registry key, HKEY into a path. And there's no API to do that. You will need to keep track of the path and pass it to the function in the question, along with the HKEY.
You are passing uninitialized values to RegEnumValue, specifically dataSize. Since you don't care about the data, don't ask for it. Pass NULL for the data pointer, and zero for data size.
Your call to new is not allocating enough memory. You need space for the directory name, the file extension, and the null-terminator.
These problems are exacerbated by your complete neglect for error checking. That might sound harsh, but frankly you need some shock treatment. In order to be able to fail gracefully you need to check for errors. More pressing for you, in order to be able to debug code, you need to check for errors.
You've tagged the code C++ but write as if it were C. If you really are using C++ then you can use standard containers, std::string, avoid raw memory allocation and the result leaks. Yes, you code leaks as it stands.

Answer 2

first of all your program is more C like than C++, but if you want to solve this in C++ you can use stringstream in the following way:
std::stringstream stream;
stream << "C:\\";
stream << valueName;
stream << ".txt";
std::string filename(stream.str());
HANDLE hFile=CreateFile(filename.c_str() ,GENERIC_READ,FILE_SHARE_READ,
NULL, CREATE_NEW , FILE_ATTRIBUTE_NORMAL,NULL);
Also you need a include:
#include <sstream>