Opening/creating a file help

[jDurks619]

One of the things i need to do in my switch statement is open/create a file if it doesn't exist, I have it all coded but I'm just not sure if it does what it is supposed to do.

Also if i have any other minor/major errors in any other cases if you pointed them out if would help a lot, in most of the case functions I've just wrote cout's of what I'm going to do in them but I'm mostly worried about case1 for now, also in case 5 i found some code to do what is needed for that case which is displaying the largest number, but i just have to re-write it for my program.

#include <iostream>
#include <fstream>
#include <string>

using namespace std;	

string case1();
int case2();
int bubbleSort();
int case4();
int case5();
int case6();
void exit();

int main()
{
	char repeatMenu = 0;
	string fileName = "";

	do {

		system("cls");

		cout << "** MENU **" << endl << endl;

		cout << "Current Data File: " << fileName;

		cout << endl << endl;

		int menuChoice;

		cout << "(1) Select / Create data file (.txt file extension will be added automatically)\n";
		cout << "(2) Display all numbers, total and average\n";
		cout << "(3) Display all numbers sorted\n";
		cout << "(4) Search for a number and display how many times it occurs\n";
		cout << "(5) Display the largest number\n";
		cout << "(6) Append a random number(s)\n";
		cout << "(7) Exit the program\n";

		cout << endl;

		cout << "Menu choice: ";
		cin >> menuChoice;

		if (menuChoice < 1 || menuChoice > 7)
		{
			do
			{
				cout << "Menu choice: ";
				cin >> menuChoice;
			} while (menuChoice < 1 || menuChoice > 7);
		}

		cout << endl << endl;

		switch (menuChoice)

		{
		
		case 1:		fileName = case1();
					break;
		case 2:		fileName = case2();
					break;
		case 3:		fileName = bubbleSort();
					break;
		case 4:		fileName = case4();
					break;
		case 5:		fileName = case5();
					break;
		case 6:		fileName = case6();
					break;
		case 7:		exit();
					break;

		}

		cout << endl;
		cout << "Would you like to return to the main menu ? [Y/N]: ";
		cin >> repeatMenu;

	} while (repeatMenu == 'Y' || repeatMenu == 'y');

	("pause");
	return 0;
}

string case1()
{
	string fileName;
	fstream fileName1;

	cout << "Please select the name of the file you would like to open: ";
	cin >> fileName;

	fileName = fileName + ".txt";

	fileName1.open(fileName, ios::in);

	if (fileName1.fail())
	{
		cout << "The file you selected does not exist.\n";
		cout << "Creating file named the filename you selected.\n\n";

		fileName1.open(fileName);
	}

	else
	{
		cout << "The filename you selected exists and is opened.\n";
	}
	return fileName;
}

int case2()
{
	cout << "Display all the numbers, total and average";
	cout << " in the selected filename";
	cout << endl << endl;

	return 0;
}

int bubbleSort()
{
	cout << "Create a bubble sort and display ";
        cout << "all the numbers sorted.\n\n";

	return 0;
}

int case4()
{
	cout << "Sort array and use binary search";

	return 0;
}

int case5()
{
	//int numbers[];
	//int count;
	//int highest;
	//highest = numbers[0];

	//for (count = 1; count < SIZE; count++)
	{
	//	if (numbers[count] > highest)
	//		highest = numbers[count];
	}

	system("pause");
	return 0;
}

int case6()
{
	cout << "Append a random number and open the file using ios::app";
	cout << endl << endl;

	return 0;
}

void exit()
{
	cout << "Bye, have a great day!";
	cout << endl << endl;

	system("pause");

	exit(0);

	return;
}

[JayhawkZombie]

You can use std::ofstream to create the file for you if it doesn't already exist. std::ifstream doesn't create files if they don't exist.

http://www.cplusplus.com/reference/fstream/ofstream/

#include <fstream>
#include <iostream>
#include <string>

int main()
{
	std::string filename = "test.txt";
	std::string extracted = "";
	std::ifstream infile;
	std::ofstream outfile;

	std::cout << "Enter file name: ";
	std::cin >> filename;

	infile.open(filename);

	if (infile.fail())
	{
		std::cerr << "No file found matching name: " << filename << std::endl;
		//Create file
		infile.close();
		outfile.open(filename);
		outfile << "New test file content\n";
		outfile.close();
	}

	infile.open(filename);

	while (infile)
	{
		std::getline(infile, extracted);
		std::cout << extracted << std::endl;
	}
	infile.close();
}

[jDurks619]

When i put that in case 1 and compile the program and call the case1 function by selecting 1 after input a file name it gives me a invalid null pointer error, even if the file name exists and makes me abort.

[JayhawkZombie]

Don't just take my code and smack it in. Use it as an example so that you can do the same for your project. Adapt my code to fit your needs.