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  4. structure to file [REMAIN UNSOLVED] [CLOSED]

structure to file [REMAIN UNSOLVED] [CLOSED]

Scheduled Pinned Locked Moved C / C++ / MFC
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  • G goldenrose9

    DavidCrow wrote:

    You probably meant to use _tcscpy() here instead.

    This works like a charm

    _tcscpy(st.detail.Name,TEXT("Williams"));
    _tcscpy(st.detail.Address,TEXT("B-33 Lane 5"));

    But another problem arises cannot set values in long and DWORD variables

    struct Detail{
    wchar_t Name[25];
    long Age;
    wchar_t Address[100];
    };

    struct Student{
    Detail detail;
    DWORD code;
    };

    Student st;
    st.code = 1;

    but st.code stores a default value of -16843010 and same problem with long data type st.Details.Age = 25 stores 65278, instead of 25. :confused: :wtf: MODIFIED: _tcscpy_s() now works. i was making a small mistake. Now it works..

    _tcscpy_s(st.detail.Name,_tcslen(st.detail.Name),TEXT("WILLIAMS"));

    Some Day I Will Prove MySelf :: GOLD

    modified on Wednesday, February 16, 2011 10:43 PM

    D Offline
    D Offline
    David Crow
    wrote on last edited by
    #9

    goldenrose9 wrote:

    why error is occurring in _tcscpy_s()

    Hard to say since you did not indicate what the error was.

    "One man's wage rise is another man's price increase." - Harold Wilson

    "Fireproof doesn't mean the fire will never come. It means when the fire comes that you will be able to withstand it." - Michael Simmons

    "Man who follows car will be exhausted." - Confucius

    1 Reply Last reply
    0
    • G goldenrose9

      DavidCrow wrote:

      You probably meant to use _tcscpy() here instead.

      This works like a charm

      _tcscpy(st.detail.Name,TEXT("Williams"));
      _tcscpy(st.detail.Address,TEXT("B-33 Lane 5"));

      But another problem arises cannot set values in long and DWORD variables

      struct Detail{
      wchar_t Name[25];
      long Age;
      wchar_t Address[100];
      };

      struct Student{
      Detail detail;
      DWORD code;
      };

      Student st;
      st.code = 1;

      but st.code stores a default value of -16843010 and same problem with long data type st.Details.Age = 25 stores 65278, instead of 25. :confused: :wtf: MODIFIED: _tcscpy_s() now works. i was making a small mistake. Now it works..

      _tcscpy_s(st.detail.Name,_tcslen(st.detail.Name),TEXT("WILLIAMS"));

      Some Day I Will Prove MySelf :: GOLD

      modified on Wednesday, February 16, 2011 10:43 PM

      S Offline
      S Offline
      ShilpiP
      wrote on last edited by
      #10

      Try ZeroMemory

      Student st,read;
      ZeroMemory(&st,sizeof(st));

      I believe in LOVE AT FIRST SIGHT... Bcoz I have loved my Mother... even since I opened my eyes...(ICAN)

      N 1 Reply Last reply
      0
      • G goldenrose9

        #include <windows.h>
        #include <conio.h>
        #include <iostream>

        using namespace std;

        struct Detail{
        wchar_t Name[25];
        long Age;
        wchar_t Address[100];
        };

        struct Student{
        Detail detail;
        DWORD code;
        };

        int main()
        {

        DWORD BytesWritten=0, BytesRead=0;
Student st,read;

st.code =1;
st.detail.Name = TEXT("Williams");
st.detail.Age = 25;
st.detail.Address = TEXT("B-33 Lane 5");


HANDLE hFile = CreateFile(TEXT("C:\\\\demo.txt"),GENERIC\_READ | GENERIC\_WRITE,0,0,OPEN\_ALWAYS,FILE\_ATTRIBUTE\_NORMAL,0);
if (hFile != INVALID\_HANDLE\_VALUE)
{
	WriteFile(hFile,&st,sizeof(Student),&BytesWritten,0);
	ReadFile(hFile,&read,sizeof(Student),&BytesRead,0);
	CloseHandle(hFile);

	cout<<read.code<<endl;
	cout<<read.detail.Name; 
}
else
{
	cout<<"Error! Cannot Open File";
	exit(1);
}
\_getche();
return (0);

        }

        when executing this code following error occurs.

        Error 1 error C2440: '=' : cannot convert from 'const wchar_t [9]' to 'wchar_t [25]'
        Error 2 error C2440: '=' : cannot convert from 'const wchar_t [12]' to 'wchar_t [100]'

        Some Day I Will Prove MySelf :: GOLD

        L Offline
        L Offline
        Lost User
        wrote on last edited by
        #11

        st.detail.Name = TEXT("Williams");

        You cannot copy characters in this way, you must use one of the copy methods.

        I must get a clever new signature for 2011.

        1 Reply Last reply
        0
        • S ShilpiP

          Try ZeroMemory

          Student st,read;
          ZeroMemory(&st,sizeof(st));

          I believe in LOVE AT FIRST SIGHT... Bcoz I have loved my Mother... even since I opened my eyes...(ICAN)

          N Offline
          N Offline
          Niklas L
          wrote on last edited by
          #12

          To OP: This is only meaningful if you don't intend to initialize every member separately.

          home

          1 Reply Last reply
          0
          • G goldenrose9

            DavidCrow wrote:

            You probably meant to use _tcscpy() here instead.

            This works like a charm

            _tcscpy(st.detail.Name,TEXT("Williams"));
            _tcscpy(st.detail.Address,TEXT("B-33 Lane 5"));

            But another problem arises cannot set values in long and DWORD variables

            struct Detail{
            wchar_t Name[25];
            long Age;
            wchar_t Address[100];
            };

            struct Student{
            Detail detail;
            DWORD code;
            };

            Student st;
            st.code = 1;

            but st.code stores a default value of -16843010 and same problem with long data type st.Details.Age = 25 stores 65278, instead of 25. :confused: :wtf: MODIFIED: _tcscpy_s() now works. i was making a small mistake. Now it works..

            _tcscpy_s(st.detail.Name,_tcslen(st.detail.Name),TEXT("WILLIAMS"));

            Some Day I Will Prove MySelf :: GOLD

            modified on Wednesday, February 16, 2011 10:43 PM

            D Offline
            D Offline
            David Crow
            wrote on last edited by
            #13

            goldenrose9 wrote:

            i was making a small mistake.

            And you still are. _tcslen() does not tell you the size/capacity of Name, but rather how many characters it is currently holding.

            "One man's wage rise is another man's price increase." - Harold Wilson

            "Fireproof doesn't mean the fire will never come. It means when the fire comes that you will be able to withstand it." - Michael Simmons

            "Man who follows car will be exhausted." - Confucius

            G 1 Reply Last reply
            0
            • D David Crow

              goldenrose9 wrote:

              i was making a small mistake.

              And you still are. _tcslen() does not tell you the size/capacity of Name, but rather how many characters it is currently holding.

              "One man's wage rise is another man's price increase." - Harold Wilson

              "Fireproof doesn't mean the fire will never come. It means when the fire comes that you will be able to withstand it." - Michael Simmons

              "Man who follows car will be exhausted." - Confucius

              G Offline
              G Offline
              goldenrose9
              wrote on last edited by
              #14

              yes you are right. but when i use

              _tcscpy_s(st.detail.Name,sizeof(st.detail.Name),TEXT("WILLIAMS"));

              stack around st get corrupted. moreover when i initialize st with

              st.code =1;
              st.detail.Age = 25;

              then the value is changed to

              st.code = 4278124286
              st.detail.Age = -16843010

              i had intialized the st as given

              st.code =1;
              st.detail.Age = 25;
              _tcscpy_s(st.detail.Name,sizeof(st.detail.Name),TEXT("WILLIAMS"));
              _tcscpy_s(st.detail.Address,sizeof(st.detail.Address),TEXT("BB-33 LANE 5"));

              Some Day I Will Prove MySelf :: GOLD

              D 1 Reply Last reply
              0
              • G goldenrose9

                yes you are right. but when i use

                _tcscpy_s(st.detail.Name,sizeof(st.detail.Name),TEXT("WILLIAMS"));

                stack around st get corrupted. moreover when i initialize st with

                st.code =1;
                st.detail.Age = 25;

                then the value is changed to

                st.code = 4278124286
                st.detail.Age = -16843010

                i had intialized the st as given

                st.code =1;
                st.detail.Age = 25;
                _tcscpy_s(st.detail.Name,sizeof(st.detail.Name),TEXT("WILLIAMS"));
                _tcscpy_s(st.detail.Address,sizeof(st.detail.Address),TEXT("BB-33 LANE 5"));

                Some Day I Will Prove MySelf :: GOLD

                D Offline
                D Offline
                David Crow
                wrote on last edited by
                #15

                Have you considered:

                st.code = 1;
                st.st.Age = 25;
                _tcscpy_s(st.st.Name, sizeof(st.st.Name), TEXT("WILLIAMS"));
                _tcscpy_s(st.st.Address, sizeof(st.st.Address), TEXT("BB-33 LANE 5"));

                For clarities sake, you might consider renaming the st member of Student.

                "One man's wage rise is another man's price increase." - Harold Wilson

                "Fireproof doesn't mean the fire will never come. It means when the fire comes that you will be able to withstand it." - Michael Simmons

                "Man who follows car will be exhausted." - Confucius

                G 1 Reply Last reply
                0
                • D David Crow

                  Have you considered:

                  st.code = 1;
                  st.st.Age = 25;
                  _tcscpy_s(st.st.Name, sizeof(st.st.Name), TEXT("WILLIAMS"));
                  _tcscpy_s(st.st.Address, sizeof(st.st.Address), TEXT("BB-33 LANE 5"));

                  For clarities sake, you might consider renaming the st member of Student.

                  "One man's wage rise is another man's price increase." - Harold Wilson

                  "Fireproof doesn't mean the fire will never come. It means when the fire comes that you will be able to withstand it." - Michael Simmons

                  "Man who follows car will be exhausted." - Confucius

                  G Offline
                  G Offline
                  goldenrose9
                  wrote on last edited by
                  #16

                  whenever st.code and st.st.Age is initialized with any value the result is,

                  st.code = 4278124286
                  st.detail.Age = -16843010

                  Some Day I Will Prove MySelf :: GOLD

                  D 1 Reply Last reply
                  0
                  • G goldenrose9

                    whenever st.code and st.st.Age is initialized with any value the result is,

                    st.code = 4278124286
                    st.detail.Age = -16843010

                    Some Day I Will Prove MySelf :: GOLD

                    D Offline
                    D Offline
                    David Crow
                    wrote on last edited by
                    #17

                    You need to look more closely at the code snippet I provided. You should not be assigning or referencing st.Detail. In your Student structure, Detail is a type of structure, not an instance of one.

                    "One man's wage rise is another man's price increase." - Harold Wilson

                    "Fireproof doesn't mean the fire will never come. It means when the fire comes that you will be able to withstand it." - Michael Simmons

                    "Man who follows car will be exhausted." - Confucius

                    G 1 Reply Last reply
                    0
                    • D David Crow

                      You need to look more closely at the code snippet I provided. You should not be assigning or referencing st.Detail. In your Student structure, Detail is a type of structure, not an instance of one.

                      "One man's wage rise is another man's price increase." - Harold Wilson

                      "Fireproof doesn't mean the fire will never come. It means when the fire comes that you will be able to withstand it." - Michael Simmons

                      "Man who follows car will be exhausted." - Confucius

                      G Offline
                      G Offline
                      goldenrose9
                      wrote on last edited by
                      #18

                      please give a small example. :confused:

                      Some Day I Will Prove MySelf :: GOLD

                      D 1 Reply Last reply
                      0
                      • G goldenrose9

                        please give a small example. :confused:

                        Some Day I Will Prove MySelf :: GOLD

                        D Offline
                        D Offline
                        David Crow
                        wrote on last edited by
                        #19

                        See here.

                        "One man's wage rise is another man's price increase." - Harold Wilson

                        "Fireproof doesn't mean the fire will never come. It means when the fire comes that you will be able to withstand it." - Michael Simmons

                        "Man who follows car will be exhausted." - Confucius

                        G 1 Reply Last reply
                        0
                        • D David Crow

                          See here.

                          "One man's wage rise is another man's price increase." - Harold Wilson

                          "Fireproof doesn't mean the fire will never come. It means when the fire comes that you will be able to withstand it." - Michael Simmons

                          "Man who follows car will be exhausted." - Confucius

                          G Offline
                          G Offline
                          goldenrose9
                          wrote on last edited by
                          #20

                          on using

                          st.code = 1;
                          st.st.Age = 25;
                          _tcscpy_s(st.st.Name, sizeof(st.st.Name), TEXT("WILLIAMS"));
                          _tcscpy_s(st.st.Address, sizeof(st.st.Address), TEXT("BB-33 LANE 5"));

                          following error occurs.

                          Error 1 error C2039: 'st' : is not a member of 'Student'
                          Error 2 error C2228: left of '.Age' must have class/struct/union

                          Some Day I Will Prove MySelf :: GOLD

                          D 1 Reply Last reply
                          0
                          • G goldenrose9

                            on using

                            st.code = 1;
                            st.st.Age = 25;
                            _tcscpy_s(st.st.Name, sizeof(st.st.Name), TEXT("WILLIAMS"));
                            _tcscpy_s(st.st.Address, sizeof(st.st.Address), TEXT("BB-33 LANE 5"));

                            following error occurs.

                            Error 1 error C2039: 'st' : is not a member of 'Student'
                            Error 2 error C2228: left of '.Age' must have class/struct/union

                            Some Day I Will Prove MySelf :: GOLD

                            D Offline
                            D Offline
                            David Crow
                            wrote on last edited by
                            #21

                            I just compiled your code with my changes. It compiled and ran fine.

                            "One man's wage rise is another man's price increase." - Harold Wilson

                            "Fireproof doesn't mean the fire will never come. It means when the fire comes that you will be able to withstand it." - Michael Simmons

                            "Man who follows car will be exhausted." - Confucius

                            G 1 Reply Last reply
                            0
                            • D David Crow

                              I just compiled your code with my changes. It compiled and ran fine.

                              "One man's wage rise is another man's price increase." - Harold Wilson

                              "Fireproof doesn't mean the fire will never come. It means when the fire comes that you will be able to withstand it." - Michael Simmons

                              "Man who follows car will be exhausted." - Confucius

                              G Offline
                              G Offline
                              goldenrose9
                              wrote on last edited by
                              #22

                              please give a sample so that i can understand my mistake.

                              Some Day I Will Prove MySelf :: GOLD

                              1 Reply Last reply
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