读取注册表

#include <iostream>
#include <assert.h>
#include <windows.h>
#include <tchar.h>
#include <conio.h>
#include <stdio.h>
using namespace std;

void wcharTochar(const wchar_t* wchar, char* chr, int length)
{
    WideCharToMultiByte(CP_ACP, 0, wchar, -1,
        chr, length, NULL, NULL);
}

bool OpenRegKey(HKEY& hRetKey)
{
    LPCWSTR sw = _T("SOFTWARE\Classes\FeikuaBrowserFile.myp\DefaultIcon");
    wprintf(L"SW is %s
", sw);
    if (ERROR_SUCCESS == RegOpenKey(HKEY_LOCAL_MACHINE, sw, &hRetKey))
    {
        return true;
    }
    printf("OpenRegKey return is false!
");
    return false;
}

bool QueryRegKey(LPCWSTR strSubKey, LPCWSTR strValueName, char* strValue, int length)//这里是传4个参数
{
    DWORD dwType = REG_SZ;//定义数据类型
    DWORD dwLen = MAX_PATH;

    wchar_t data[MAX_PATH];
    HKEY hKey;
    HKEY hSubKey;
    if (OpenRegKey(hKey))
    {
        if (ERROR_SUCCESS == RegOpenKey(HKEY_LOCAL_MACHINE, strSubKey, &hSubKey))
        {
            TCHAR buf[256] = { 0 };

            if (ERROR_SUCCESS == RegQueryValueEx(hSubKey, strValueName, 0, &dwType, (LPBYTE)data, &dwLen))
            {
                wcharTochar(data, strValue, length);
                wprintf(L"data = %s,len= %d
", data, strlen((const char*)data));
                RegCloseKey(hKey); //关闭注册表
                return true;
            }
        }
        RegCloseKey(hKey); //关闭注册表
    }

    return false;
}
int main()
{ 
    HKEY  hKey = NULL;
    string result;
    LPCWSTR strSubKey = _T("SOFTWARE\Classes\FeikuaBrowserFile.myp\DefaultIcon");
    LPCWSTR strValueName = _T("");
    char strValue[256];
    int length = 256;
    bool status = QueryRegKey(strSubKey, strValueName, strValue, length);
    printf("status is %d
", status);
    printf("result is %s
", strValue);
    return 0;
}

默认值按空串处理