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  4. problem with fwrite

problem with fwrite

Scheduled Pinned Locked Moved C / C++ / MFC
helpdebugging
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  • C Cadimi

    I wrote a short code to write the status of my program to a file, but when debug in that code, I realize that fwrite function still increase its file pointer but when I read that file by fread function, I can't read that value. This is my code: // TODO: Add your control notification handler code here //write config file FILE *fout = fopen( "config.pcm", "wb" ); if ( fout ) { //write the time of power function fwrite( &m_uTime, sizeof( int ), 1, fout ); unsigned long temp; //write tasks //number of day task temp = m_alltasks.size(); fwrite( &temp, sizeof( long ), 1, fout ); for ( int i = 0; i < m_alltasks.size(); i++ ) { //date fwrite( &m_alltasks[i].date, sizeof( MYDATE ), 1, fout ); //number of notes in that day temp = m_alltasks[i].tasks.size(); fwrite( &temp, sizeof( long ), 1, fout ); //notes for ( int j = 0; j < m_alltasks[i].tasks.size(); j++ ) { fwrite( &m_alltasks[i].tasks[j], sizeof( TASK ), 1, fout ); } } //how many hotkeys have been defined temp = m_hkArr.size(); fwrite( &temp, sizeof( long ), 1, fout ); //write the list of hotkeys for ( int i = 0; i < temp; i++ ) fwrite( &m_hkArr[i], sizeof( HOTKEY ), 1, fout ); fclose( fout ); } else { MessageBox( _T( "Can't write config file" ), _T( "Warning" ) ); OnCancel(); } //unregister hotkeys for ( int i = 0; i < m_hkArr.size(); i++ ) { UnregisterHotKey( m_hWnd, m_hkArr[i].id ); GlobalDeleteAtom( m_hkArr[i].id ); } OnCancel(); They all work except for the code I bolded ( file pointer still increase, but the file is not change )... Help me plz >.<...

    CPalliniC Offline
    CPalliniC Offline
    CPallini
    wrote on last edited by
    #2

    How did you check the file was not actually written? How did you define m_hkArr? How was HOTKEY defined? :)

    If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler. -- Alfonso the Wise, 13th Century King of Castile.
    This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong. -- Iain Clarke

    In testa che avete, signor di Ceprano?

    C 1 Reply Last reply
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    • CPalliniC CPallini

      How did you check the file was not actually written? How did you define m_hkArr? How was HOTKEY defined? :)

      If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler. -- Alfonso the Wise, 13th Century King of Castile.
      This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong. -- Iain Clarke

      C Offline
      C Offline
      Cadimi
      wrote on last edited by
      #3

      I do it on Visual Studio 2005 SP1. I added config.pcm into my solution. After I had run my program, if config.pcm changed the content, then Visual Studio would ask you to update the content of that file. When I debug, I see the file pointer increase, but after I closed fout, VS didn't ask me to update the content -> the content hadn't been modified. m_hkArr is vector m_hkArr. The structure of struct HOTKEY: struct HOTKEY { BOOL isCtrl; UINT c; TCHAR szPath[256]; int id; //id of this hot key }; This struct is self-identified Hotkey :D. I just check for Ctrl or Alt is press with the key. id is the ID of the hotkey, return value of GlobalAddAtom. The code I have posted just a bit of my code

      CPalliniC 1 Reply Last reply
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      • C Cadimi

        I do it on Visual Studio 2005 SP1. I added config.pcm into my solution. After I had run my program, if config.pcm changed the content, then Visual Studio would ask you to update the content of that file. When I debug, I see the file pointer increase, but after I closed fout, VS didn't ask me to update the content -> the content hadn't been modified. m_hkArr is vector m_hkArr. The structure of struct HOTKEY: struct HOTKEY { BOOL isCtrl; UINT c; TCHAR szPath[256]; int id; //id of this hot key }; This struct is self-identified Hotkey :D. I just check for Ctrl or Alt is press with the key. id is the ID of the hotkey, return value of GlobalAddAtom. The code I have posted just a bit of my code

        CPalliniC Offline
        CPalliniC Offline
        CPallini
        wrote on last edited by
        #4

        Are you sure you're writing to the same file that is open by Visual Studio?

        If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler. -- Alfonso the Wise, 13th Century King of Castile.
        This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong. -- Iain Clarke

        In testa che avete, signor di Ceprano?

        C 1 Reply Last reply
        0
        • CPalliniC CPallini

          Are you sure you're writing to the same file that is open by Visual Studio?

          If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler. -- Alfonso the Wise, 13th Century King of Castile.
          This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong. -- Iain Clarke

          C Offline
          C Offline
          Cadimi
          wrote on last edited by
          #5

          yes, When I change the config of my program, so, it have to write in the config.pcm. All the configurations of my program are written on config.pcm except for the hotkeys ( the bolded code )

          CPalliniC 1 Reply Last reply
          0
          • C Cadimi

            yes, When I change the config of my program, so, it have to write in the config.pcm. All the configurations of my program are written on config.pcm except for the hotkeys ( the bolded code )

            CPalliniC Offline
            CPalliniC Offline
            CPallini
            wrote on last edited by
            #6

            How can you see the file pointer advancing? How many HOTKEY items did you successfully write (i.e. Did you check temp value? Did you check fwrite return value?)? :)

            If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler. -- Alfonso the Wise, 13th Century King of Castile.
            This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong. -- Iain Clarke

            In testa che avete, signor di Ceprano?

            C 1 Reply Last reply
            0
            • CPalliniC CPallini

              How can you see the file pointer advancing? How many HOTKEY items did you successfully write (i.e. Did you check temp value? Did you check fwrite return value?)? :)

              If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler. -- Alfonso the Wise, 13th Century King of Castile.
              This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong. -- Iain Clarke

              C Offline
              C Offline
              Cadimi
              wrote on last edited by
              #7

              when debuging, just watch for the file pointer, so, I can see fout increase the value, I write 1 or 2 HOTKEY to try, but the content no change. When I read the file, the value is 0 >.<

              CPalliniC 1 Reply Last reply
              0
              • C Cadimi

                when debuging, just watch for the file pointer, so, I can see fout increase the value, I write 1 or 2 HOTKEY to try, but the content no change. When I read the file, the value is 0 >.<

                CPalliniC Offline
                CPalliniC Offline
                CPallini
                wrote on last edited by
                #8

                Cadimi wrote:

                I write 1 or 2 HOTKEY to try

                But then do you close the file?

                If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler. -- Alfonso the Wise, 13th Century King of Castile.
                This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong. -- Iain Clarke

                In testa che avete, signor di Ceprano?

                C 1 Reply Last reply
                0
                • CPalliniC CPallini

                  Cadimi wrote:

                  I write 1 or 2 HOTKEY to try

                  But then do you close the file?

                  If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler. -- Alfonso the Wise, 13th Century King of Castile.
                  This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong. -- Iain Clarke

                  C Offline
                  C Offline
                  Cadimi
                  wrote on last edited by
                  #9

                  as you can see in the code, I closed it, and before closed it, I fflush( fout ) carefully :D

                  CPalliniC 1 Reply Last reply
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                  • C Cadimi

                    as you can see in the code, I closed it, and before closed it, I fflush( fout ) carefully :D

                    CPalliniC Offline
                    CPalliniC Offline
                    CPallini
                    wrote on last edited by
                    #10

                    Yes, I saw the code, anyway I was referring to you debugging actions (i.e. I didn't know if you stopped the program after few write operations). The reason behind my questions is I cannot believe fwrite silently failing, it never happened to me. Can't you isolate the failing piece of the writing routine and run it in a simpler context (for instance another, adhoc, project)?

                    If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler. -- Alfonso the Wise, 13th Century King of Castile.
                    This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong. -- Iain Clarke

                    In testa che avete, signor di Ceprano?

                    C 1 Reply Last reply
                    0
                    • CPalliniC CPallini

                      Yes, I saw the code, anyway I was referring to you debugging actions (i.e. I didn't know if you stopped the program after few write operations). The reason behind my questions is I cannot believe fwrite silently failing, it never happened to me. Can't you isolate the failing piece of the writing routine and run it in a simpler context (for instance another, adhoc, project)?

                      If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler. -- Alfonso the Wise, 13th Century King of Castile.
                      This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong. -- Iain Clarke

                      C Offline
                      C Offline
                      Cadimi
                      wrote on last edited by
                      #11

                      thanks for your help, that's the worse thing I've ever met >.<

                      1 Reply Last reply
                      0
                      • C Cadimi

                        I wrote a short code to write the status of my program to a file, but when debug in that code, I realize that fwrite function still increase its file pointer but when I read that file by fread function, I can't read that value. This is my code: // TODO: Add your control notification handler code here //write config file FILE *fout = fopen( "config.pcm", "wb" ); if ( fout ) { //write the time of power function fwrite( &m_uTime, sizeof( int ), 1, fout ); unsigned long temp; //write tasks //number of day task temp = m_alltasks.size(); fwrite( &temp, sizeof( long ), 1, fout ); for ( int i = 0; i < m_alltasks.size(); i++ ) { //date fwrite( &m_alltasks[i].date, sizeof( MYDATE ), 1, fout ); //number of notes in that day temp = m_alltasks[i].tasks.size(); fwrite( &temp, sizeof( long ), 1, fout ); //notes for ( int j = 0; j < m_alltasks[i].tasks.size(); j++ ) { fwrite( &m_alltasks[i].tasks[j], sizeof( TASK ), 1, fout ); } } //how many hotkeys have been defined temp = m_hkArr.size(); fwrite( &temp, sizeof( long ), 1, fout ); //write the list of hotkeys for ( int i = 0; i < temp; i++ ) fwrite( &m_hkArr[i], sizeof( HOTKEY ), 1, fout ); fclose( fout ); } else { MessageBox( _T( "Can't write config file" ), _T( "Warning" ) ); OnCancel(); } //unregister hotkeys for ( int i = 0; i < m_hkArr.size(); i++ ) { UnregisterHotKey( m_hWnd, m_hkArr[i].id ); GlobalDeleteAtom( m_hkArr[i].id ); } OnCancel(); They all work except for the code I bolded ( file pointer still increase, but the file is not change )... Help me plz >.<...

                        D Offline
                        D Offline
                        David Crow
                        wrote on last edited by
                        #12

                        Cadimi wrote:

                        FILE *fout = fopen( "config.pcm", "wb" );

                        Are you using a relative path? What is the value of temp?

                        "Love people and use things, not love things and use people." - Unknown

                        "To have a respect for ourselves guides our morals; to have deference for others governs our manners." - Laurence Sterne

                        C 1 Reply Last reply
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                        • D David Crow

                          Cadimi wrote:

                          FILE *fout = fopen( "config.pcm", "wb" );

                          Are you using a relative path? What is the value of temp?

                          "Love people and use things, not love things and use people." - Unknown

                          "To have a respect for ourselves guides our morals; to have deference for others governs our manners." - Laurence Sterne

                          C Offline
                          C Offline
                          Cadimi
                          wrote on last edited by
                          #13

                          temp is the number of hotkeys, its value is the size of the vector contain my HOTKEY struct

                          D 1 Reply Last reply
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                          • C Cadimi

                            temp is the number of hotkeys, its value is the size of the vector contain my HOTKEY struct

                            D Offline
                            D Offline
                            David Crow
                            wrote on last edited by
                            #14

                            Cadimi wrote:

                            temp is the number of hotkeys, its value is the size of the vector contain my HOTKEY struct

                            I know what it represents. I asked what its value was (at the time of writing to the file).

                            "Love people and use things, not love things and use people." - Unknown

                            "To have a respect for ourselves guides our morals; to have deference for others governs our manners." - Laurence Sterne

                            C 1 Reply Last reply
                            0
                            • D David Crow

                              Cadimi wrote:

                              temp is the number of hotkeys, its value is the size of the vector contain my HOTKEY struct

                              I know what it represents. I asked what its value was (at the time of writing to the file).

                              "Love people and use things, not love things and use people." - Unknown

                              "To have a respect for ourselves guides our morals; to have deference for others governs our manners." - Laurence Sterne

                              C Offline
                              C Offline
                              Cadimi
                              wrote on last edited by
                              #15

                              I tried a simple example, its value at that time is 1

                              D 1 Reply Last reply
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                              • C Cadimi

                                I tried a simple example, its value at that time is 1

                                D Offline
                                D Offline
                                David Crow
                                wrote on last edited by
                                #16

                                Ok, what do the two subsequent calls to fwrite() return?

                                "Love people and use things, not love things and use people." - Unknown

                                "To have a respect for ourselves guides our morals; to have deference for others governs our manners." - Laurence Sterne

                                C 1 Reply Last reply
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                                • D David Crow

                                  Ok, what do the two subsequent calls to fwrite() return?

                                  "Love people and use things, not love things and use people." - Unknown

                                  "To have a respect for ourselves guides our morals; to have deference for others governs our manners." - Laurence Sterne

                                  C Offline
                                  C Offline
                                  Cadimi
                                  wrote on last edited by
                                  #17

                                  I just watch the file pointer, it increase the value equal to the size I've requested to write on file

                                  D 1 Reply Last reply
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                                  • C Cadimi

                                    I just watch the file pointer, it increase the value equal to the size I've requested to write on file

                                    D Offline
                                    D Offline
                                    David Crow
                                    wrote on last edited by
                                    #18

                                    But what do the two subsequent calls to fwrite() return?

                                    "Love people and use things, not love things and use people." - Unknown

                                    "To have a respect for ourselves guides our morals; to have deference for others governs our manners." - Laurence Sterne

                                    C 1 Reply Last reply
                                    0
                                    • D David Crow

                                      But what do the two subsequent calls to fwrite() return?

                                      "Love people and use things, not love things and use people." - Unknown

                                      "To have a respect for ourselves guides our morals; to have deference for others governs our manners." - Laurence Sterne

                                      C Offline
                                      C Offline
                                      Cadimi
                                      wrote on last edited by
                                      #19

                                      I've found my problem :D... It happened when I ust CFileDialog in another code, select a path, then the default directory change too => write file at another place => can't read. Thanks for your help

                                      D 1 Reply Last reply
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                                      • C Cadimi

                                        I've found my problem :D... It happened when I ust CFileDialog in another code, select a path, then the default directory change too => write file at another place => can't read. Thanks for your help

                                        D Offline
                                        D Offline
                                        David Crow
                                        wrote on last edited by
                                        #20

                                        Cadimi wrote:

                                        ...can't read.

                                        Which is why I was asking if fopen() was failing.

                                        "Love people and use things, not love things and use people." - Unknown

                                        "To have a respect for ourselves guides our morals; to have deference for others governs our manners." - Laurence Sterne

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