delete content form a file

bru · 04-28-2004, 08:37 PM

I figured it out but thanks for trying to help!!!

I am creating a "Database" using an array to store the information, and have created most of the menu options, except search & delete!!! And I can not seam to figure it out.

Code:

#include <iostream>
#include <cstring>
#include <fstream>

using namespace std;

struct Score //notice its not plural

{                   // making record fields

    char student[50];
    char studentscore[50];
    int how_many;

};

//does this work???
void add_Score(int&, Score []); 
void list_Score(int, Score[]); 

int main()

{
    int num_students;

    Score Scores[50];//notices its plural
    char choice; // switch satement for asking questions
    fstream scoresdb; // data file

   scoresdb.open("scoresdb.dat");

   if (!scoresdb)

   {

	   cout << "Cannot open input file.\n";
	   return 1;

   }

    scoresdb >> num_students;   //reading the file

    for(int i=0; i < num_students; i++)

    {

	    scoresdb.getline(Scores[i].student, 50);
	    scoresdb.getline(Scores[i].studentscore, 50); 
            scoresdb >> Scores[i].student;
            scoresdb >> Scores[i].studentscore;
            scoresdb >> Scores[i].how_many;
    }

    do
    {
	cout << "What is your choice?" << endl;
	cin >> choice;
	choice = toupper(choice);

	switch (choice) 				      	

	  {                                                       

/*add*/		case 'A':  add_Score(num_students, Scores);

			cout << "\nnum_students in main after Add: "; //not sure if needed
			cout << num_students << endl;                 //not sure if needed
			break;

/*list*/	case 'L':  list_Score(num_students, Scores);
			break;

/*delete*/	case 'D': index = 0; //Is it 'index' or what? is this even right?
			while (index < lenght && item != data[index])
				Score++;

			if (index < length)
			{
				data[index] = data [lenghth-1];
				lenght--;
			}
			break;

/*search*/	case 'S': 

	     case 'Q':
                      break;

	     default:   cout << "Error in choice.  Please try again."  << endl;
      }

   }while (choice != 'Q');

   dbfile.close();

   return 0;

} // end of main function

Thanks in advance for the help

ssba · 04-30-2004, 07:41 AM

I do not know C file handling, so forgive me if I make a mistake.. but I see quite a few in your 'Delete' block I think you should take a look at:

Code:

while (index < lenght && item != data[index])
	Score++;

You misspelt 'length' here. I'm assuming thats what you want? I don't see any place where you have defined 'length' anyways. On another note: This looks like an infinite loop to me. 'index' is never modified.

Code:

if (index < length)
	{

Once again, I don't think 'length' has been defined yet.

Code:

data[index] = data [lenghth-1];

Yet another misspelling of 'length'.

Code:

lenght--;

And another.

I don't know if the above is all 100% correct, but I do believe that your misspellings of 'length' are some of your problem. =P