在C ++中的注册表中写入/读取字符串

Question

如何在C ++中的Windows注册表中写入/读取字符串？

我可以使用以下代码在Windows注册表中写入/读取DWORD（数字）。 但是，无法写入/读取字符串值，因为它像汉字一样存储在注册表中。

void SetVal(HKEY hKey, LPCTSTR lpValue, DWORD data)
{
    LONG nError = RegSetValueEx(hKey, lpValue, NULL, REG_DWORD, (LPBYTE)&data, sizeof(DWORD));

    if (nError)
        cout << "Error: " << nError << " Could not set registry value: " << (char*)lpValue << endl;
}

DWORD GetVal(HKEY hKey, LPCTSTR lpValue)
{
    DWORD data;     DWORD size = sizeof(data);  DWORD type = REG_DWORD;
    LONG nError = RegQueryValueEx(hKey, lpValue, NULL, &type, (LPBYTE)&data, &size);

    if (nError==ERROR_FILE_NOT_FOUND)
        data = 0; // The value will be created and set to data next time SetVal() is called.
    else if (nError)
        cout << "Error: " << nError << " Could not get registry value " << (char*)lpValue << endl;

    return data;
}

用于写入/读取字符串值的代码（在注册表中以中文之类的字符存储）：

void SetVal(HKEY hKey, LPCTSTR lpValue, string data)
{
    LONG nError = RegSetValueEx(hKey, lpValue, NULL, REG_SZ, (LPBYTE)&data, sizeof(data));

    if (nError)
        cout << "Error: " << nError << " Could not set registry value: " << (char*)lpValue << endl;
}

string GetVal(HKEY hKey, LPCTSTR lpValue)
{
    string data;     DWORD size = sizeof(data);  DWORD type = REG_SZ;
    LONG nError = RegQueryValueEx(hKey, lpValue, NULL, &type, (LPBYTE)&data, &size);

    if (nError==ERROR_FILE_NOT_FOUND)
        data = "0"; // The value will be created and set to data next time SetVal() is called.
    else if (nError)
        cout << "Error: " << nError << " Could not get registry value " << (char*)lpValue << endl;

    return data;
}

Answer 1

代码的问题在于，您天真地将string类型的变量转换为LPBYTE 。

这是经过更正的代码：

void SetVal(HKEY hKey, LPCTSTR lpValue, string data)
{
  const char *x = data.c_str();
  LONG nError = RegSetValueEx(hKey, lpValue, NULL, REG_SZ, (LPBYTE)data.c_str(), data.size());

  if (nError)
    cout << "Error: " << nError << " Could not set registry value: " << (char*)lpValue << endl;
}

string GetVal(HKEY hKey, LPCTSTR lpValue)
{
  string data; 
#define MAXLENGTH 100

  char buffer[100];
  DWORD size = sizeof(buffer);
  DWORD type = REG_SZ;

  LONG nError = RegQueryValueEx(hKey, lpValue, NULL, &type, (LPBYTE)buffer, &size);

  if (nError == ERROR_FILE_NOT_FOUND)
  {
    data = "0"; // The value will be created and set to data next time SetVal() is called.
    return data;
  }
  else if (nError)
    cout << "Error: " << nError << " Could not get registry value " << (char*)lpValue << endl;

  data = buffer;
  return data;
}

仍有改进的空间，例如，最大字符串长度限制为100，并且应改进错误处理。

说明：

这是您在SetVal的代码

RegSetValueEx(hKey, lpValue, NULL, REG_DWORD, (LPBYTE)&data, sizeof(DWORD));

• 您天真地将data投射到LPBYTE 。
• sizeof(DWORD)是错误的，因为您需要提供字符串的长度

这是您在GetVal的代码：

    string data;
    DWORD size = sizeof(data);
    DWORD type = REG_SZ;
    LONG nError = RegQueryValueEx(hKey, lpValue, NULL, &type, (LPBYTE)&data, &size);

• 当data是string时， sizeof(data)没有任何意义。 它不是字符串的长度，那时候无论如何都是0。
• 您再次在调用RegQueryValueEx时将天真string为LPBYTE