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c++ - C++ 中 "this"的可能值是 Null 吗？

转载 作者：搜寻专家 更新时间：2023-10-31 01:31:35 24 4
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<分区>

我对我的一个本地 C++ 类中“this”的 NULL 值感到困惑。

我在 stdafx.h 中这样声明类:

extern Filing* Files;

然后像这样在 stdafx.cpp 中实现它:

Filing* Files = new Filing();

调试器在此方法上阻塞，并抛出“写访问冲突”:消息还说:“这是 nullptr”。

void Filing::Startup()
{
this->ExePath = this->GetPathToExe(); //Throws right here
this->LogDirectoryPath = this->GetLogDirectoryPath();
CreateDirectory(LogDirectoryPath->c_str(), NULL);
}

这怎么可能？我该如何解决？完整的“归档”标题和定义如下。

归档.h:

#pragma once

#include <Windows.h>
#include <sstream>

using namespace std;

class Filing
{
  public:
     Filing();
     ~Filing();

/// <summary>
/// The path to this exe.
/// </summary>
     wstring* ExePath;

/// <summary>
/// The path to the log folder that exists or will be created.
/// </summary>
    wstring* LogDirectoryPath;

/// <summary>
/// Kicks off some startup logic.
/// </summary>
    void Startup();

/// <summary>
/// Determines if the specified directory exists.
/// </summary>
/// <param name="Path"></param>
/// <returns></returns>
    bool DoesDirectoryExist(string* Path);

  private:

/// <summary>
/// Returns the directory from which this executable is running from.
/// </summary>
    wstring* GetPathToExe();

/// <summary>
/// Gets the path to the log directory.
/// </summary>
/// <returns></returns>
    wstring* GetLogDirectoryPath();
};

归档.cpp:

#include "stdafx.h"
#include "Filing.h"

Filing::Filing()
{
   this->Startup();
}

Filing::~Filing()
{
   delete this->ExePath;
   delete this->LogDirectoryPath;
}

void Filing::Startup()
{
   this->ExePath = this->GetPathToExe();
   this->LogDirectoryPath = this->GetLogDirectoryPath();
   CreateDirectory(LogDirectoryPath->c_str(), NULL);
}

bool Filing::DoesDirectoryExist(string* Path)
{
   DWORD ftyp = GetFileAttributesA(Path->c_str());

   if (ftyp == INVALID_FILE_ATTRIBUTES)
   {
     Console->WriteLine("Invalid path!");
     return false;  //something is wrong with your path!
   }

   if (ftyp & FILE_ATTRIBUTE_DIRECTORY)
   {
      return true;   // this is a directory!
   }

   return false;    // this is not a directory!
}

wstring* Filing::GetPathToExe()
{
   #ifdef UNICODE
   TCHAR ownPth[260];
   #else
   char ownPth[MAX_Path];
   #endif // UNICODE

   // Will contain exe path
   HMODULE hModule = GetModuleHandle(NULL);
   if (hModule != NULL)
   {
      // When passing NULL to GetModuleHandle, it returns handle of exe itself
      GetModuleFileName(hModule, ownPth, (sizeof(ownPth)));
      return new wstring(ownPth);
   }
   else
   {
      throw new exception("Error! NullPointerException!");
   }
}

wstring* Filing::GetLogDirectoryPath()
{
   //if (this == nullptr)
   //{
   //   int i = 0;
   //}

   wstring *directory;
   const size_t last_slash_idx = ExePath->rfind('\\');
   if (string::npos != last_slash_idx)
   {
      directory = new wstring(ExePath->substr(0, last_slash_idx));
      directory->append(L"\\Logs");
   }
   else
   {
      throw new exception("Error! Directory not found from path!");
   }
   return directory;
}

到目前为止我尝试过的事情:

清理和重建。

正在初始化归档。

编辑:

我看到一些关于不使用 stdafx.h 和 stdafx.cpp 的评论。我现在将它们用于全局变量/类。我如何在别处定义它们并且仍然是全局的？

编辑2:

一直将错误追溯到一个小的 GetTime() 函数。

const char* Writer::GetTime()
{
    string* Formatted = new string("[");
    time_t rawtime;
    tm* timeinfo;
    char buffer[80];
    time(&rawtime);
    timeinfo = std::localtime(&rawtime);

    strftime(buffer, 80, "%Y-%m-%d-%H-%M-%S", timeinfo);
    Formatted->append(buffer);
    Formatted->append("]: ");

    const char* Ret = Formatted->c_str();

    delete Formatted;
    delete timeinfo;//Errors here SOMETIMES. Any ideas?
    return Ret;
}

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