C++ 是否真的可以在MFC'；通过使用CFile和CStdio类来实现？

是否真的可以使用

CFile

和

CStdio

类将数据附加到MFC中的文本文件中？如果可以，如何添加

UpdateData(TRUE);
CStdioFile file_object;//(L"D://Docs//Temp.txt",
    CFile::modeCreate | CFile::modeReadWrite | CFile::modeRead); 
CString str = L"D://Docs//Temp.txt";
CString fc1, fc2;

BOOL bFile = file_object.Open(str, 
    CFile::modeCreate | CFile::modeReadWrite | CFile::modeRead);
if (bFile)
    file_object.Seek(file_object.GetLength(), CFile::end);

fc1.Format(L"%f", m_CelTemp);
file_object.WriteString(L"Temp in Celsius is:");     
file_object.WriteString(fc1);
file_object.WriteString(L"\n");

fc2.Format(L"%f", m_FarTemp);
file_object.WriteString(L"Temp in Fahrenheit is:");      
file_object.WriteString(fc2);
file_object.WriteString(L"\n");

UpdateData(FALSE); 

我使用了下面的代码来附加数据，但它只提供了最新的（最后输入的）数据

UpdateData(TRUE);
CStdioFile file_object;//(L"D://Docs//Temp.txt",
    CFile::modeCreate | CFile::modeReadWrite | CFile::modeRead); 
CString str = L"D://Docs//Temp.txt";
CString fc1, fc2;

BOOL bFile = file_object.Open(str, 
    CFile::modeCreate | CFile::modeReadWrite | CFile::modeRead);
if (bFile)
    file_object.Seek(file_object.GetLength(), CFile::end);

fc1.Format(L"%f", m_CelTemp);
file_object.WriteString(L"Temp in Celsius is:");     
file_object.WriteString(fc1);
file_object.WriteString(L"\n");

fc2.Format(L"%f", m_FarTemp);
file_object.WriteString(L"Temp in Fahrenheit is:");      
file_object.WriteString(fc2);
file_object.WriteString(L"\n");

UpdateData(FALSE); 

---

首先，您发布的内容不会编译，从第3行开始。请张贴真实代码

UpdateData(TRUE);
CStdioFile file_object;//(L"D://Docs//Temp.txt",
    CFile::modeCreate | CFile::modeReadWrite | CFile::modeRead); 
CString str = L"D://Docs//Temp.txt";
CString fc1, fc2;

BOOL bFile = file_object.Open(str, 
    CFile::modeCreate | CFile::modeReadWrite | CFile::modeRead);
if (bFile)
    file_object.Seek(file_object.GetLength(), CFile::end);

fc1.Format(L"%f", m_CelTemp);
file_object.WriteString(L"Temp in Celsius is:");     
file_object.WriteString(fc1);
file_object.WriteString(L"\n");

fc2.Format(L"%f", m_FarTemp);
file_object.WriteString(L"Temp in Fahrenheit is:");      
file_object.WriteString(fc2);
file_object.WriteString(L"\n");

UpdateData(FALSE); 

---

最好的猜测是问题出在

CFile:：modeCreate

上，它“如果没有文件存在，则创建一个新文件；如果文件已经存在，则会引发CFileException。”（请参阅中的参考文档）。您可能需要“打开现有”的

CFile:：modeNoTruncate

。

您应该使用

CFile:：SeekToEnd（）

方法设置指向文件逻辑结尾的文件指针的值，以便追加数据

UpdateData(TRUE);
CStdioFile file_object;//(L"D://Docs//Temp.txt",
    CFile::modeCreate | CFile::modeReadWrite | CFile::modeRead); 
CString str = L"D://Docs//Temp.txt";
CString fc1, fc2;

BOOL bFile = file_object.Open(str, 
    CFile::modeCreate | CFile::modeReadWrite | CFile::modeRead);
if (bFile)
    file_object.Seek(file_object.GetLength(), CFile::end);

fc1.Format(L"%f", m_CelTemp);
file_object.WriteString(L"Temp in Celsius is:");     
file_object.WriteString(fc1);
file_object.WriteString(L"\n");

fc2.Format(L"%f", m_FarTemp);
file_object.WriteString(L"Temp in Fahrenheit is:");      
file_object.WriteString(fc2);
file_object.WriteString(L"\n");

UpdateData(FALSE); 

以下是一个例子：

UpdateData(TRUE);
CStdioFile file_object;//(L"D://Docs//Temp.txt",
    CFile::modeCreate | CFile::modeReadWrite | CFile::modeRead); 
CString str = L"D://Docs//Temp.txt";
CString fc1, fc2;

BOOL bFile = file_object.Open(str, 
    CFile::modeCreate | CFile::modeReadWrite | CFile::modeRead);
if (bFile)
    file_object.Seek(file_object.GetLength(), CFile::end);

fc1.Format(L"%f", m_CelTemp);
file_object.WriteString(L"Temp in Celsius is:");     
file_object.WriteString(fc1);
file_object.WriteString(L"\n");

fc2.Format(L"%f", m_FarTemp);
file_object.WriteString(L"Temp in Fahrenheit is:");      
file_object.WriteString(fc2);
file_object.WriteString(L"\n");

UpdateData(FALSE); 

CStdioFile f;
CString sDataToWrite(_T("Data\r\n"));
if(f.Open(_T("C:\\Files\\file.txt"), CFile::modeCreate | CFile::modeNoTruncate | CFile::modeWrite)) 
{
      f.SeekToEnd();
      f.WriteString(sDataToWrite);  
}
f.Close();

---

这是您可以尝试的示例代码

UpdateData(TRUE);
CStdioFile file_object;//(L"D://Docs//Temp.txt",
    CFile::modeCreate | CFile::modeReadWrite | CFile::modeRead); 
CString str = L"D://Docs//Temp.txt";
CString fc1, fc2;

BOOL bFile = file_object.Open(str, 
    CFile::modeCreate | CFile::modeReadWrite | CFile::modeRead);
if (bFile)
    file_object.Seek(file_object.GetLength(), CFile::end);

fc1.Format(L"%f", m_CelTemp);
file_object.WriteString(L"Temp in Celsius is:");     
file_object.WriteString(fc1);
file_object.WriteString(L"\n");

fc2.Format(L"%f", m_FarTemp);
file_object.WriteString(L"Temp in Fahrenheit is:");      
file_object.WriteString(fc2);
file_object.WriteString(L"\n");

UpdateData(FALSE); 

CStdioFile file;
file.Open(_T("_FILE_PATH_HERE"),CFile::modeCreate|CFile::modeWrite|CFile::modeNoTruncate);
file.SeekToEnd();
file.WriteString(_T("Write Text Here\r\n")); // \r\n to move the cursor to the next line
file.Close();

CFile:：modeCreate如果不存在文件，则创建一个新文件。；如果文件已经存在，则会引发CFileException

UpdateData(TRUE);
CStdioFile file_object;//(L"D://Docs//Temp.txt",
    CFile::modeCreate | CFile::modeReadWrite | CFile::modeRead); 
CString str = L"D://Docs//Temp.txt";
CString fc1, fc2;

BOOL bFile = file_object.Open(str, 
    CFile::modeCreate | CFile::modeReadWrite | CFile::modeRead);
if (bFile)
    file_object.Seek(file_object.GetLength(), CFile::end);

fc1.Format(L"%f", m_CelTemp);
file_object.WriteString(L"Temp in Celsius is:");     
file_object.WriteString(fc1);
file_object.WriteString(L"\n");

fc2.Format(L"%f", m_FarTemp);
file_object.WriteString(L"Temp in Fahrenheit is:");      
file_object.WriteString(fc2);
file_object.WriteString(L"\n");

UpdateData(FALSE); 

CFile:：modeNoTruncate如果不存在文件，则创建一个新文件；否则，如果文件已存在，则会将其附加到CFile对象

UpdateData(TRUE);
CStdioFile file_object;//(L"D://Docs//Temp.txt",
    CFile::modeCreate | CFile::modeReadWrite | CFile::modeRead); 
CString str = L"D://Docs//Temp.txt";
CString fc1, fc2;

BOOL bFile = file_object.Open(str, 
    CFile::modeCreate | CFile::modeReadWrite | CFile::modeRead);
if (bFile)
    file_object.Seek(file_object.GetLength(), CFile::end);

fc1.Format(L"%f", m_CelTemp);
file_object.WriteString(L"Temp in Celsius is:");     
file_object.WriteString(fc1);
file_object.WriteString(L"\n");

fc2.Format(L"%f", m_FarTemp);
file_object.WriteString(L"Temp in Fahrenheit is:");      
file_object.WriteString(fc2);
file_object.WriteString(L"\n");

UpdateData(FALSE); 

CFile:：modeWrite仅请求写访问权限

UpdateData(TRUE);
CStdioFile file_object;//(L"D://Docs//Temp.txt",
    CFile::modeCreate | CFile::modeReadWrite | CFile::modeRead); 
CString str = L"D://Docs//Temp.txt";
CString fc1, fc2;

BOOL bFile = file_object.Open(str, 
    CFile::modeCreate | CFile::modeReadWrite | CFile::modeRead);
if (bFile)
    file_object.Seek(file_object.GetLength(), CFile::end);

fc1.Format(L"%f", m_CelTemp);
file_object.WriteString(L"Temp in Celsius is:");     
file_object.WriteString(fc1);
file_object.WriteString(L"\n");

fc2.Format(L"%f", m_FarTemp);
file_object.WriteString(L"Temp in Fahrenheit is:");      
file_object.WriteString(fc2);
file_object.WriteString(L"\n");

UpdateData(FALSE); 

---

file.SeekToEnd（）设置指向文件逻辑结尾的文件指针的值。

是，可以使用CFile和CStdioFile追加数据。

UpdateData(TRUE);
CStdioFile file_object;//(L"D://Docs//Temp.txt",
    CFile::modeCreate | CFile::modeReadWrite | CFile::modeRead); 
CString str = L"D://Docs//Temp.txt";
CString fc1, fc2;

BOOL bFile = file_object.Open(str, 
    CFile::modeCreate | CFile::modeReadWrite | CFile::modeRead);
if (bFile)
    file_object.Seek(file_object.GetLength(), CFile::end);

fc1.Format(L"%f", m_CelTemp);
file_object.WriteString(L"Temp in Celsius is:");     
file_object.WriteString(fc1);
file_object.WriteString(L"\n");

fc2.Format(L"%f", m_FarTemp);
file_object.WriteString(L"Temp in Fahrenheit is:");      
file_object.WriteString(fc2);
file_object.WriteString(L"\n");

UpdateData(FALSE); 

你必须使用

UpdateData(TRUE);
CStdioFile file_object;//(L"D://Docs//Temp.txt",
    CFile::modeCreate | CFile::modeReadWrite | CFile::modeRead); 
CString str = L"D://Docs//Temp.txt";
CString fc1, fc2;

BOOL bFile = file_object.Open(str, 
    CFile::modeCreate | CFile::modeReadWrite | CFile::modeRead);
if (bFile)
    file_object.Seek(file_object.GetLength(), CFile::end);

fc1.Format(L"%f", m_CelTemp);
file_object.WriteString(L"Temp in Celsius is:");     
file_object.WriteString(fc1);
file_object.WriteString(L"\n");

fc2.Format(L"%f", m_FarTemp);
file_object.WriteString(L"Temp in Fahrenheit is:");      
file_object.WriteString(fc2);
file_object.WriteString(L"\n");

UpdateData(FALSE); 

FileObj.Open（L“FileName.txt”，CFile:：modeCreate | CFile:：modeWrite | CFile:：modeNoTruncate）

UpdateData(TRUE);
CStdioFile file_object;//(L"D://Docs//Temp.txt",
    CFile::modeCreate | CFile::modeReadWrite | CFile::modeRead); 
CString str = L"D://Docs//Temp.txt";
CString fc1, fc2;

BOOL bFile = file_object.Open(str, 
    CFile::modeCreate | CFile::modeReadWrite | CFile::modeRead);
if (bFile)
    file_object.Seek(file_object.GetLength(), CFile::end);

fc1.Format(L"%f", m_CelTemp);
file_object.WriteString(L"Temp in Celsius is:");     
file_object.WriteString(fc1);
file_object.WriteString(L"\n");

fc2.Format(L"%f", m_FarTemp);
file_object.WriteString(L"Temp in Fahrenheit is:");      
file_object.WriteString(fc2);
file_object.WriteString(L"\n");

UpdateData(FALSE); 

简单例子

UpdateData(TRUE);
CStdioFile file_object;//(L"D://Docs//Temp.txt",
    CFile::modeCreate | CFile::modeReadWrite | CFile::modeRead); 
CString str = L"D://Docs//Temp.txt";
CString fc1, fc2;

BOOL bFile = file_object.Open(str, 
    CFile::modeCreate | CFile::modeReadWrite | CFile::modeRead);
if (bFile)
    file_object.Seek(file_object.GetLength(), CFile::end);

fc1.Format(L"%f", m_CelTemp);
file_object.WriteString(L"Temp in Celsius is:");     
file_object.WriteString(fc1);
file_object.WriteString(L"\n");

fc2.Format(L"%f", m_FarTemp);
file_object.WriteString(L"Temp in Fahrenheit is:");      
file_object.WriteString(fc2);
file_object.WriteString(L"\n");

UpdateData(FALSE); 

CFile FileObj;
//CStdioFile FileObj;

//  FileObj.Open(L"FileName.txt",CStdioFile ::modeCreate | CStdioFile::modeWrite | CStdioFile::modeNoTruncate);
FileObj.Open(L"FileName.txt",CFile ::modeCreate | CFile::modeWrite | CFile::modeNoTruncate);
FileObj.SeekToEnd();
CString Message = m_strName ;       // Whetever Your Message
FileObj.Write(Message,Message.GetLength());
FileObj.Flush();
FileObj.Close();

---

你的代码无法编译，有明显的错误。比如@Barmakshemirantry。另请参见发布指南中关于最小但完整示例的部分。@UlrichEckhart但请告诉我，我应该尝试什么？我也尝试过这个，但是在调试过程中，我检查了光标指针在输入第一组详细信息后是否不会结束。问题是，您使用的是带有错误参数的

Seek

方法，而不是

SeekToEnd（）

好吧，假设我不使用Seek方法，那么我应该怎么做，有其他方法吗？？

SeekToEnd（）

是一种方法：我更新了答案，为您提供了一个如何使用它的示例。如果没有文件，NotRuncate不会创建文件。这是文件中的一个错误。从2008年起就知道了，这很有趣。

modeCreate

覆盖现有文件。这是如何工作的？如果

CFile:：modeCreate

在文件已经存在时抛出异常，那么您的代码将永远不会附加到现有文件。