C ++字符转换

Question

I googled it for 2 hours now, and i can't find an answer for my problem: i need to get a registry REG_SZ value and pass it to a char* .

char host_val[1024];
DWORD hostVal_size = 1024;
char* hostName;
DWORD dwType = REG_SZ;

RegOpenKeyEx(//no problem here);
if( RegQueryValueEx( hKey, TEXT("HostName"), 0, &dwType, (LPBYTE)&host_val, &hostVal_size ) == ERROR_SUCCESS )
{
      //hostName = host_val; 
} 

How should i do this conversion hostName = host_val ?

Answer 1

The resulting host_val is a possibly non-null-terminated string (see "Remarks"), so you should copy it to a newly allocated string with memcpy , and ensure it's null-terminated:

hostName = new char[hostVal_size + 1];
// host_val may or may not be null-terminated
memcpy(hostName, host_val, hostVal_size);
hostName[hostVal_size] = '\0';

You will need to delete[] the hostName later.

Answer 2

use the ANSI version of the function

RegQueryValueExA

that way you don't need to convert.

Answer 3

If you're compiling with Unicode you're copying a Unicode string (that is possibly NOT terminated) into a narrow char buffer. the first character in the unicode string will be 0x3100 (accounting for the endianness on your machine, which is likely little-endian, and the fact that you said the IP address is 192....)

That value stuffed into the char[] array will report back as a single-char-null-terminated string. You have two options.

1. Use RegQueryValueExA, everything else stays the same, or
2. Change your char[] array to a wchar_t[] array, do what you're currently doing, then convert to narrow using WideCharToMultiByte(docs are in the SDK).

For obvious reasons, I'd take the former of those two options.