C++

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2d array: File I/O

sudhirs18 (7)
Hi,

The program below takes input from user the marks of 10 students in 6 subjects
and gives output as:

Maths Phy Chem Bio C.Sc Eng Tot Stud_Avg
studentname1    10   20   30  40   50  60  210   35
studentname2    20   30   40  50   60  70  270   45
   --
   --
studentname10   30   40   50  60   70  80  330   55


Issue faced:
the program executes and outputs the above in the output window. It,however, does not write to and read from a file in the same manner...just displays the 6 subject names on the file:-)

i've tried file i/o using object sfil of classes ofstream & ifstream. Is this correct? Could any of the experts have a look at the program & give a solution....would be of much help.

Also, apologize for the lengthy program as i'm new to c++.

thank you for your patience,
Sudhir


//compiler used turbo c++

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#include<iostream.h>
#include<fstream.h>
#include<conio.h>
class StudList
      {
         char stud_name[10][20],ans;
         char subject[6][20];
         int stud_marks[10][6],sum[10],i,j,num,sub;
         float studavg[10],subavg[6];
         public:
         void getinp()
            {
               for(ans='y',i=0;i<10&&ans=='y';i++)
	     {
	       cout<<"Enter student name"<<i+1<<endl;
	       cin>>stud_name[i];
	       cout<<"More ? (y/n)"<<endl;
	       cin>>ans;
	      }
	    for(ans='y',j=0;j<6&&ans=='y';j++)
	      {
	       cout<<"Enter subject"<<j+1<<endl;
	       cin>>subject[j];
	       cout<<"More ? (y/n)"<<endl;
	       cin>>ans;
	      }
	   num=i;
	   sub=j;
            }
           void acceptmarks()
             {
                for(i=0;i<num;i++)
	     {
	      for(j=0;j<sub;j++)
	            {
		stud_marks[i][j]=0;
		cout<<"Enter marks for "<<stud_name[i]<<" in "<<subject[j<<endl;
		cin>>stud_marks[i][j];
	            }
	     }
              }
            void calc_totmarks()
              {
	   for(i=0;i<num;i++)
	        {
	           sum[i]=0;
	           for(j=0;j<sub;j++)
		 {
		  studavg[i]=0;
		  sum[i]+=stud_marks[i][j];
		  studavg[i]+=(float)sum[i]/sub;
		 }
	         }
               }
             int disp_records()
                {
	   cout<<"       Maths Phy Chem Bio C.Sc Eng Total Stud_Avg"<<endl;
	   for(i=0;i<num;i++)
	       {
	         cout<<stud_name[i]<<" ";
	         for(j=0;j<sub;j++)
	              {
		if((stud_name[i]==stud_name[j])||(i!=j))
		cout<<stud_marks[i][j]<<"   ";
	              }
	          cout<<sum[i]<<"  ";
	          cout<<studavg[i]<<endl;
	        }
	   return 0;
	}
  };
int main()
  {
   ofstream sfil("prog97.txt");
   clrscr();
   StudList obj;
   obj.getinp();
   obj.acceptmarks();
   obj.calc_totmarks();
   sfil<<"Student Database:"<<endl;
   sfil<<"-------------------------\n"<<endl;
   sfil<<"       Maths Phy Chem Bio C.Sc Eng Total Stud_Avg"<<endl;
   sfil<<obj.disp_records();
   sfil.close();
   cout<<"Do you want to view the contents of the file(y/n)?"<<endl;
   char choice;
   if(choice=='Y'||choice=='y')
     {
       ifstream sfil("prog97.txt");
       ifstream in("prog97.txt");
       char str1[21],str2[31];
       char stdnm1[21],stdnm2[21],stdnm3[21],stdnm4[21],stdnm5[21],stdnm6[21];
       char stdnm7[21],stdnm8[21],stdnm9[21],stdnm10[21];
       char sub1[11],sub2[11],sub3[11],sub4[11],sub5[11],sub6[11];
       char tot[11],avg[11];
       int mrks1,mrks2,mrks3,mrks4,mrks5,mrks6,mrks7,mrks8,mrks9,mrks10;
       int mrks11,mrks12,mrks13,mrks14,mrks15,mrks16,mrks17,mrks18,mrks19,
           mrks20;
       int mrks21,mrks22,mrks23,mrks24,mrks25,mrks26,mrks27,mrks28,mrks29,
           mrks30;
       int mrks31,mrks32,mrks33,mrks34,mrks35,mrks36,mrks37,mrks38,mrks39,
           mrks40;
       int mrks41,mrks42,mrks43,mrks44,mrks45,mrks46,mrks47,mrks48,mrks49,
           mrks50;
       int mrks51,mrks52,mrks53,mrks54,mrks55,mrks56,mrks57,mrks58,mrks59,
           mrks60;
       int tot1,tot2,tot3,tot4,tot5,tot6,tot7,tot8,tot9,tot10;
       float avg1,avg2,avg3,avg4,avg5,avg6,avg7,avg8,avg9,avg10;
       in.get(str1,21);
       in.get(str2,31);
       in.get(sub1,11);
       in.get(sub2,11);
       in.get(sub3,11);
       in.get(sub4,11);
       in.get(sub5,11);
       in.get(sub6,11);
       in.get(tot,11);
       in.get(avg,11);
       in.get(stdnm1,21);
       sfil>>mrks1;
       sfil>>mrks2;
       sfil>>mrks3;
       sfil>>mrks4;
       sfil>>mrks5;
       sfil>>mrks6;
       sfil>>tot1;
       sfil>>avg1;
       in.get(stdnm2,21);
       sfil>>mrks7;
       sfil>>mrks8;
       sfil>>mrks9;
       sfil>>mrks10;
       sfil>>mrks11;
       sfil>>mrks12;
       sfil>>tot2;
       sfil>>avg2;
       in.get(stdnm3,21);
       sfil>>mrks13;
       sfil>>mrks14;
       sfil>>mrks15;
       sfil>>mrks16;
       sfil>>mrks17;
       sfil>>mrks18;
       sfil>>tot3;
       sfil>>avg3;
       in.get(stdnm4,21);
       sfil>>mrks19;
       sfil>>mrks20;
       sfil>>mrks21;
       sfil>>mrks22;
       sfil>>mrks23;
       sfil>>mrks24;
       sfil>>tot4;
       sfil>>avg4;
       in.get(stdnm5,21);
       sfil>>mrks25;
       sfil>>mrks26;
       sfil>>mrks27;
       sfil>>mrks28;
       sfil>>mrks29;
       sfil>>mrks30;
       sfil>>tot5;
       sfil>>avg5;
       in.get(stdnm6,21);
       sfil>>mrks31;
       sfil>>mrks32;
       sfil>>mrks33;
       sfil>>mrks34;
       sfil>>mrks35;
       sfil>>mrks36;
       sfil>>tot6;
       sfil>>avg6;
       in.get(stdnm7,21);
       sfil>>mrks37;
       sfil>>mrks38;
       sfil>>mrks39;
       sfil>>mrks40;
       sfil>>mrks41;
       sfil>>mrks42;
       sfil>>tot7;
       sfil>>avg7;
       in.get(stdnm8,21);
       sfil>>mrks43;
       sfil>>mrks44;
       sfil>>mrks45;
       sfil>>mrks46;
       sfil>>mrks47;
       sfil>>mrks48;
       sfil>>tot8;
       sfil>>avg8;
       in.get(stdnm9,21);
       sfil>>mrks49;
       sfil>>mrks50;
       sfil>>mrks51;
       sfil>>mrks52;
       sfil>>mrks53;
       sfil>>mrks54;
       sfil>>tot9;
       sfil>>avg9;
       in.get(stdnm10,21);
       sfil>>mrks55;
       sfil>>mrks56;
       sfil>>mrks57;
       sfil>>mrks58;
       sfil>>mrks59;
       sfil>>mrks60;
       sfil>>tot10;
       sfil>>avg10;
     }
   getch();
return 0;
}
Last edited on
kbw (9488)
Can't you find a way to put all those marks in an array or something? With so many variable lying around, how can you be sure you've not made a mistake?

Are you familiar with struct? If you are, you should consider using an array of structs of stuff withing the class.

In your code:
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	char choice;
	if(choice=='Y'||choice=='y')

choice is used before it's assigned a value.

EDIT: Can you use the code format tags for your code.
Last edited on
sudhirs18 (7)
once again, apologies for the cluttered and lengthy code (i've already mentioned my newbie status).....in the meanwhile will try arrays and revert.

As regards the variable "choice", should the code be modified to

Original:
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cout<<"Do you want to view the contents of the file(y/n)?"<<endl;
   char choice;
   if(choice=='Y'||choice=='y')



Modified:
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   char choice;
   cout<<"Do you want to view the contents of the file(y/n)?"<<endl;
   cin>>choice;
   if(choice=='Y'||choice=='y')


to take appropriate user input? If yes, it does not change the output on the file [still only the 6 subject names displayed without the student names, marks etc...]
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