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generic code for writing structures, help me make it more generic

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  2 months ago

  by anh85

  thai anh

  , Viet Nam

  Joined 6 months ago

  well ive got a program that scans a structure from cin and puts it in a binary file, and can also take it out of the binary file and display it. i like the interface ive made very much, i want to use this code for many many projects without having to change much,
  
  especially for many different types of structures,
  
  so im trying to make it more generic, but i havent a clue how to proceed. my guess is that ill have to use some element of classes.
  
  im not asking u to write my code i just want a hint. anything at all would be greatly appreciated
  
  take a look:
  
  exportimportstructmain.cpp
  #include <iostream>
  #include <fstream>
  #include "exportimportstructdec.h"
  using namespace std;
  
  grades myGradesi,myGradeso,myGradesa;
  
  //declare pointers to structures for file io:
  grades * pMyGradeso=&myGradeso;
  grades * pMyGradesa=&myGradesa;
  grades * pMyGradesi;
  
  int main ()
  {
      int choice;
      char opFile[]="binary.bin";
      char opMessage[]=" please enter 4 grades separated by pressing enter ";
      char menu[]=" do u want to 1, read from the file, or 2, write over the file or 3, append the file or 4, exit the program? ";
      //give the user options:
      do
      {
          cout<<menu;
          cin>>choice;
          //option 1, read from the file:
          if (choice==1)
          {
              readfile(opFile,myGradesi,pMyGradesi);
          }
          //option 2, write over the file:
          if (choice==2)
          {
              wrtfile(opFile,opMessage,myGradeso,pMyGradeso);
          }
          //option 3, append the file:
          if (choice==3)
          {
              appfile(opFile,opMessage,myGradesa,pMyGradesa);
          }
      //option 4, exit:
      }while (choice!=4);
      return 0;
  }
  exportimportstructdef.cpp
  #include <iostream>
  #include <fstream>
  #include "exportimportstructdec.h"
  using namespace std;
  
  extern grades myGradesi, myGradeso, myGradesa;
  extern grades pMyGradeso, *pMyGradesa, *pMyGradesi;
  
  //the purpose of this program is to send structures into a file, and then read them from the same file
  //structure to be written:
  
  
  void readfile(char readFileName[],grades structi,grades * pStructi)
  {
      //check the size of the file and allocate appropriate memory:
      long begin,end;
      ifstream filecheck (readFileName);
      if (filecheck.is_open())
      {
          begin = filecheck.tellg();
          filecheck.seekg (0, ios::end);
          end = filecheck.tellg();
          filecheck.close();
          int fileSize=(end-begin)/(sizeof(structi));
          pStructi= new grades [fileSize];
      }
      else cout << " Unable to open file for size check ";
      //read the file into memory:
      int structArraySize=0;
      ifstream filei;
      filei.open (readFileName, ios::in|ios::binary);
      if (filei.is_open())
      {
          while ((filei.peek()!=EOF))
          {
              filei.read(reinterpret_cast<char>(&pStructi[structArraySize]), sizeof(grades));
              structArraySize++;
          }
          //display memory on screen:
          printmemory(structArraySize,pStructi);
      }
      else cout << " Unable to open file for input ";
  }
  
  
  void wrtfile(char wrtFileName[],char wrtMessage[],grades structo,grades * pStructo)
  {
      ofstream fileo;
      fileo.open (wrtFileName, ios::out|ios::binary);
      cout << wrtMessage;
      scanstruct(pStructo);
      if (fileo.isopen())
      {
          fileo.write (reinterpretcast<char>(pStructo), sizeof(structo));
          fileo.close();
      }
      else cout << " Unable to open file for output ";
  }
  
  void appfile(char appFileName[],char appMessage[],grades structa,grades * pStructa)
  {
      ofstream filea;
      filea.open (appFileName, ios::app|ios::binary);
      cout << appMessage;
      scanstruct(pStructa);
      if (filea.is_open())
      {
          filea.write (reinterpret_cast<char>(pStructa), sizeof(structa));
          filea.close();
      }
      else cout << " Unable to open file for output ";
  }
  
  void scanstruct(grades * pStructscan)
  {
      cin >> (pStructscan).grade1 >> (pStructscan).grade2 >> (pStructscan).grade3 >> (pStructscan).grade4;
  }
  
  void printmemory(int specificStructArraySize,grades * pStructi)
  {
      for(int i=0;i<specificStructArraySize;i++)
      {
          cout<<" grade1 "<< (pStructi[i]).grade1<<" grade2 "<< (pStructi[i]).grade2<<" grade3 "<< (pStructi[i]).grade3<<" grade4 "<< (pStructi[i]).grade4<<" ";
      }
  }
  
  
  exportimportstructdec.h
  #ifndef EXPORTIMPORTSTRUCTDECH
  #define EXPORTIMPORTSTRUCTDECH
  
  struct grades
  {
      int grade1;
      int grade2;
      int grade3;
      int grade4;
  };
  
  
  void printmemory(int ,grades * );
  void scanstruct(grades * );
  void readfile(char [],grades ,grades * );
  void wrtfile(char [],char [],grades ,grades * );
  void appfile(char [],char [],grades ,grades * );
  
  #endif

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• • Reply

  2 months ago

  by anh85

  thai anh

  , Viet Nam

  Joined 6 months ago

  im afraid i dont know what that nonsense   is where all of my tabs are and cant get rid of it
  

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• • Reply

  2 months ago

  by Mohammad Rastkar

  Mohammad Rastkar

  Shiraz, Iran

  Joined 2 years ago

   Hi chopficaro,

  I had a problem like yours, when I pasted some text from MS Word.

  I suggest, just paste your code from VS or a .txt file, or just type that here (first clear all of your post).
  

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