如何从 Windows 注册表中读取值 [英] How to read a value from the Windows registry

问题描述

给定某些注册表值的键(例如 HKEY_LOCAL_MACHINElahlahlahfoo)，我该如何:

Given the key for some registry value (e.g. HKEY_LOCAL_MACHINElahlahlahfoo) how can I:

1. 安全地确定存在这样的密钥.
2. 以编程方式(即使用代码)获取其值.

我绝对无意将任何内容写回注册表(如果可以的话，在我的职业生涯中).因此，如果我错误地写入注册表，我们可以跳过关于我体内每个分子以光速爆炸的讲座.

I have absolutely no intention of writing anything back to the registry (for the duration of my career if I can help it). So we can skip the lecture about every molecule in my body exploding at the speed of light if I write to the registry incorrectly.

更喜欢 C++ 中的答案，但大多数情况下只需要知道获得该值的特殊 Windows API 咒语是什么.

Prefer answers in C++, but mostly just need to know what the special Windows API incantation to get at the value is.

推荐答案

这里是一些伪代码来检索以下内容:

1. 如果注册表项存在
2. 该注册表项的默认值是什么
3. 什么是字符串值
4. 什么是 DWORD 值

示例代码:

包含库依赖:Advapi32.lib

Include the library dependency: Advapi32.lib

HKEY hKey;
LONG lRes = RegOpenKeyExW(HKEY_LOCAL_MACHINE, L"SOFTWARE\Perl", 0, KEY_READ, &hKey);
bool bExistsAndSuccess (lRes == ERROR_SUCCESS);
bool bDoesNotExistsSpecifically (lRes == ERROR_FILE_NOT_FOUND);
std::wstring strValueOfBinDir;
std::wstring strKeyDefaultValue;
GetStringRegKey(hKey, L"BinDir", strValueOfBinDir, L"bad");
GetStringRegKey(hKey, L"", strKeyDefaultValue, L"bad");

LONG GetDWORDRegKey(HKEY hKey, const std::wstring &strValueName, DWORD &nValue, DWORD nDefaultValue)
{
    nValue = nDefaultValue;
    DWORD dwBufferSize(sizeof(DWORD));
    DWORD nResult(0);
    LONG nError = ::RegQueryValueExW(hKey,
        strValueName.c_str(),
        0,
        NULL,
        reinterpret_cast<LPBYTE>(&nResult),
        &dwBufferSize);
    if (ERROR_SUCCESS == nError)
    {
        nValue = nResult;
    }
    return nError;
}


LONG GetBoolRegKey(HKEY hKey, const std::wstring &strValueName, bool &bValue, bool bDefaultValue)
{
    DWORD nDefValue((bDefaultValue) ? 1 : 0);
    DWORD nResult(nDefValue);
    LONG nError = GetDWORDRegKey(hKey, strValueName.c_str(), nResult, nDefValue);
    if (ERROR_SUCCESS == nError)
    {
        bValue = (nResult != 0) ? true : false;
    }
    return nError;
}


LONG GetStringRegKey(HKEY hKey, const std::wstring &strValueName, std::wstring &strValue, const std::wstring &strDefaultValue)
{
    strValue = strDefaultValue;
    WCHAR szBuffer[512];
    DWORD dwBufferSize = sizeof(szBuffer);
    ULONG nError;
    nError = RegQueryValueExW(hKey, strValueName.c_str(), 0, NULL, (LPBYTE)szBuffer, &dwBufferSize);
    if (ERROR_SUCCESS == nError)
    {
        strValue = szBuffer;
    }
    return nError;
}

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