My file is not being created

[seungyeon]

Write your question here.


how do I create a file?!

  #include <iostream>
#include <fstream>
#include <ctime> // Needed for the true randomization
#include <cstdlib> 

using namespace std;

struct data
{
	int ID; //000-1000
	char gender; //m for male f for female
	int credits; //0-124
};

char randChar();

int main()
{
	fstream records("findme.txt");
	records.open("findme.txt");

	if (!records.is_open())
	   {
	   cout << "File did not open!" << endl << endl;
	   }
	
	srand(time(NULL));
	
	int R;
	data cred;
	
	cout << "Enter the number of records (20-60): ";
	cin >> R;
	if (R < 20 || R > 60)
	{
		cout << "A number between 20 through 60: ";
		cin >> R;
	}
	
	records << "Number of records: " << R << endl << endl;
	
	
	for (int ix = 0; ix < R; ix++)
	{
		cred.credits = rand()%125;
		cout << endl;
		cred.ID = rand()%1001;
		cout << endl;
		//cred.gender = randChar();
		//cout << endl;
		
		records << "ID: " << cred.ID << " Gender: " << cred.gender << " Credits: " << randChar() << endl;
	}
	
	records.close();

	int credarr[100];
	records.open("findme.txt");
	int u;
	double avg=0,avgstorage;
	
	for(int jx = 0; jx < R;jx++)
	{
		avg += cred.credits;
	}
	avgstorage = avg / R;
	
	records.close();
	cout << "The file data.bin processed " << R << " records and the average number of credits is " << avgstorage << "." << endl; 

return 0;	
}

char randChar()
{
   if ( rand() % 2 )   return 'M';
   else                return 'F';
}

[AbstractionAnon]

how do I create a file?!

What problem are you having?

Line 20: This line is unnecessary. The file is implicitly opened because a filename was specified on line 19.

Line 24: If the file failed to open, you display a message, but then continue as if nothing was wrong. Not a good idea. You should call exit() or return 1.

Line 34: An if statement will only detect a single mistake. What if the user enters an invalid R multiple times? You won't detect it. This should be a while statement.

Line 52: You're writing cred.gender, but cred.gender was never initialized.

Line 52: You're writing randChar() for the number of credits.

Line 64: You are repeatedly adding the contents of cred.credits. credit was a temporary variable used in line 45-52. At this point it contains only the data for the last entry made.

[seungyeon]

updated

#include <iostream>
#include <fstream>
#include <ctime> // Needed for the true randomization
#include <cstdlib> 

using namespace std;

struct data
{
	int ID; //000-1000
	char gender; //m for male f for female
	int credits; //0-124
};

char randChar();

int main()
{
	srand(time(NULL));
	
	int R;
	data cred;
	
	ofstream records("Data.bin", ios::binary);
	records.write((char*) &cred, sizeof(data));

	if (!records.is_open())
	   {
	   cout << "File did not open!" << endl << endl;
	   }

	//records.open("data.bin");
	
	cout << "Enter the number of records (20-60): ";
	cin >> R;
	if (R < 20 || R > 60)
	{
		cout << "A number between 20 through 60: ";
		cin >> R;
	}
	
	records << "Number of records: " << R << endl << endl;
	
	
	for (int ix = 0; ix < R; ix++)
	{
		cred.credits = rand()%125;
		cout << endl;
		cred.ID = rand()%1001;
		cout << endl;
		//cred.gender = randChar();
		//cout << endl;
		
		records << "ID: " << cred.ID << " Gender: " << cred.gender << " Credits: " << randChar() << endl;
	}
	
	records.close();

	int credarr[100];
	records.open("Data.bin");
	int u;
	double avg=0,avgstorage;
	
	for(int jx = 0; jx < R;jx++)
	{
		avg += cred.credits;
	}
	avgstorage = avg / R;
	
	records.close();
	cout << "The file data.bin processed " << R << " records and the average number of credits is " << avgstorage << "." << endl; 

return 0;	
}

char randChar()
{
   if ( rand() % 2 )   return 'M';
   else                return 'F';
}

[AbstractionAnon]

Line 22: cred is uninitialized.

Line 25: You're writing an uninitialized data structure.

Line 60: records was declared as an ofstream. You're going to be opening the file for output.

All my previous comments still apply.