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Articles / Desktop Programming / MFC
Posted 18 Sep 2002


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CDocument::DoSave revealed

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4.80/5 (20 votes)
18 Sep 2002CPOL3 min read
Explains how you can suppress the File-Save-As dialog in a Doc/View app, how to save files to multiple formats, and how DoSave is implemented.


For one of my recent projects I had a rather strange requirement. It was an image conversion program basically, and it allowed you to open bitmap files. When the user clicked on the save icon in the toolbar or if he took the save-item from the File-menu, I was to save the image in a custom format using the same name as the original bitmap, but replacing the bmp extension with a custom extension. This meant that I should suppress the File-Save-As dialog. Initially I thought I simply had to override OnSaveDocument and refrain from calling the base class, but I quickly discovered that OnSaveDocument was too late to suppress the File-Save-As dialog.

DoSave revealed

I took a look at doccore.cpp and soon figured out the order in which methods got called inside the CDocument class. Essentially when the user tries to save a file, MFC command routing routes the message to

or CDocument::OnFileSaveAs depending on whether you clicked on Save or on Save-As. CDocument::OnFileSave calls CDocument::DoFileSave(). CDocument::DoFileSave() checks to see if the file exists and if it does, it proceeds to call CDocument::DoSave passing the full path of the file, else it calls CDocument::DoSave passing NULL for the file path. CDocument::OnFileSaveAs simply calls CDocument::DoSave passing NULL for the file path. Thus eventually we end up in CDocument::DoSave. So I decided that this was the method to override. CDocument::DoSave is declared thus :-

BOOL CDocument::DoSave(LPCTSTR lpszPathName, BOOL bReplace);
  • lpszPathName :- This is the full path of the file to save. If this is NULL the default implementation will prompt the user for a filename and path using the File-Save-As common dialog.
  • bReplace :- If TRUE it will replace an existing file, if FALSE it won't.

In my particular case I was least bothered with the working of the

method. My intention was to get rid of this method totally. So this is what I did - I overrode this member function and did not call the base class implementation.

BOOL CBmpToXyzDoc::DoSave(LPCTSTR lpszPathName, BOOL bReplace)
    //SrcPath is the full path of the current file
    CString DestPath = SrcPath;

    //I replace the extension with the custom one

    //Now I simply call OnSaveDocument

    //File saved successfully
    return TRUE;

That was just what I had wanted to accomplish. The user never gets prompted and the file is saved using the same name as the original except for the change in extension.

Other plausible applications

While I did not specifically require it for my project, I figured that

can be used for some other purposes too. At least one nifty usage came to my mind. Assume that I wanted to do different things based on some flag. For example assume that I want to show a Save-As dialog with JPG filter if the current file is a GIF and might want to show a Save-As dialog with GIF filter if the current file is a JPG. If so, I could show my own CFileDialog after setting the corresponding OPENFILENAME members.

BOOL CBmpToXyzDoc::DoSave(LPCTSTR lpszPathName, BOOL bReplace)
    CFileDialog fd(false);

        fd.m_ofn.lpstrFilter="JPG Files(*.jpg)\0*.jpg\0\0";
        fd.m_ofn.lpstrTitle ="Save as JPG";
        fd.m_ofn.lpstrFilter="GIF Files(*.gif)\0*.gif\0\0";
        fd.m_ofn.lpstrTitle ="Save as GIF";


    return TRUE;    

Tech notes

The CDocument::DoSave implementation is very interesting. If lpszPathName is NULL, it calls CWinApp::DoPromptFileName :-

if (!AfxGetApp()->DoPromptFileName(newName,
    return FALSE;

CWinApp::DoPromptFileName itself calls


BOOL CWinApp::DoPromptFileName(CString& fileName, 
                               UINT nIDSTitle, 
                               DWORD lFlags,
                               BOOL bOpenFileDialog, 
                               CDocTemplate* pTemplate)
    ASSERT(m_pDocManager != NULL);
    return m_pDocManager->DoPromptFileName(fileName, 
        nIDSTitle, lFlags,  bOpenFileDialog, pTemplate);

CDocManager::DoPromptFileName simply uses CFileDialog to prompt for a filename.

BOOL CDocManager::DoPromptFileName(CString& fileName, 
                                   UINT nIDSTitle, 
                                   DWORD lFlags, 
                                   BOOL bOpenFileDialog, 
                                   CDocTemplate* pTemplate)
    CFileDialog dlgFile(bOpenFileDialog, NULL, NULL, 

    CString title;

    dlgFile.m_ofn.Flags |= lFlags;


    INT_PTR nResult = dlgFile.DoModal();


Of course it does a lot of stuff in addition to just showing the file dialog. For example it will append a *.* filter to your File dialogs, which is why in addition to your document filter, you'll also see a *.* filter in the file type drop-down combo-box. Knowing how the flow proceeds is handy in the sense that if you want to customize it without hooking the window, you might simply override CWinApp::DoPromptFileName and call your own CFileDialog there (remember that this will affect both Open and Save dialogs).


This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)


About the Author

Nish Nishant
United States United States
Nish Nishant is a Principal Software Architect based out of Columbus, Ohio. He has over 17 years of software industry experience in various roles including Lead Software Architect, Principal Software Engineer, and Product Manager. Nish was a Microsoft Visual C++ MVP between 2002 and 2015.

Nish is an industry acknowledged expert in the Microsoft technology stack. He authored C++/CLI in Action for Manning Publications in 2005, and had previously co-authored Extending MFC Applications with the .NET Framework for Addison Wesley in 2003. In addition, he has over 140 published technology articles on and another 250+ blog articles on his WordPress blog. Nish is vastly experienced in team management, mentoring teams, and directing all stages of software development.

Contact Nish : If you are interested in hiring Nish as a consultant, you can reach him via his google email id voidnish.

Company Website :

Comments and Discussions

GeneralUseful! Thanks! Pin
wutuma5-Dec-12 22:01
Memberwutuma5-Dec-12 22:01 
GeneralMy vote of 5 Pin
Nithin Sundar15-Feb-11 17:59
MemberNithin Sundar15-Feb-11 17:59 
GeneralNot Virtual Pin
mvinca14-Jan-05 5:56
Membermvinca14-Jan-05 5:56 
GeneralRe: Not Virtual Pin
boz11-Feb-05 1:04
Memberboz11-Feb-05 1:04 
GeneralSave As with Encoding option Pin
Anonymous20-May-04 6:26
MemberAnonymous20-May-04 6:26 
Generalproblem in saveas Pin
Member 202398-May-03 0:01
MemberMember 202398-May-03 0:01 
Generalproblem in saveas Pin
Member 202398-May-03 0:01
MemberMember 202398-May-03 0:01 
GeneralNice article Pin
Kannan Kalyanaraman20-Sep-02 5:21
MemberKannan Kalyanaraman20-Sep-02 5:21 
GeneralRe: Nice article Pin
Nish Nishant20-Sep-02 14:25
sitebuilderNish Nishant20-Sep-02 14:25 
GeneralRe: Nice article Pin
Rosenkilde6-May-03 4:54
MemberRosenkilde6-May-03 4:54 
GeneralPretty Good Pin
Tom Welch19-Sep-02 10:10
MemberTom Welch19-Sep-02 10:10 
GeneralRe: Pretty Good Pin
Nish Nishant19-Sep-02 13:41
sitebuilderNish Nishant19-Sep-02 13:41 
GeneralHmm... Pin
Shog919-Sep-02 6:22
sitebuilderShog919-Sep-02 6:22 
GeneralRe: Hmm... Pin
Nish Nishant19-Sep-02 13:43
sitebuilderNish Nishant19-Sep-02 13:43 
GeneralRe: Hmm... Pin
Shog919-Sep-02 13:44
sitebuilderShog919-Sep-02 13:44 
GeneralA tiny little problem Pin
Yawar Maajed19-Sep-02 5:45
MemberYawar Maajed19-Sep-02 5:45 
GeneralRe: A tiny little problem Pin
Yawar Maajed19-Sep-02 5:50
MemberYawar Maajed19-Sep-02 5:50 
GeneralRe: A tiny little problem Pin
Nish Nishant19-Sep-02 13:56
sitebuilderNish Nishant19-Sep-02 13:56 
GeneralRe: A tiny little problem Pin
Nish Nishant19-Sep-02 14:00
sitebuilderNish Nishant19-Sep-02 14:00 
GeneralRe: A tiny little problem Pin
Yawar Maajed19-Sep-02 15:30
MemberYawar Maajed19-Sep-02 15:30 
GeneralRe: A tiny little problem Pin
Nish Nishant19-Sep-02 15:55
sitebuilderNish Nishant19-Sep-02 15:55 
GeneralInteresting... Pin
Roger Allen19-Sep-02 0:10
MemberRoger Allen19-Sep-02 0:10 
GeneralRe: Interesting... Pin
Nish Nishant19-Sep-02 0:12
sitebuilderNish Nishant19-Sep-02 0:12 
GeneralRe: Interesting... Pin
Joao Vaz19-Sep-02 0:27
MemberJoao Vaz19-Sep-02 0:27 
GeneralRe: Interesting... Pin
Nish Nishant19-Sep-02 0:40
sitebuilderNish Nishant19-Sep-02 0:40 

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