Thread: reading from file

Having a problem reading from an input file. Have two sets of data- account numbers and balances. I set them up in parallel arrays but the book im using does not explain anything about reading from a file. Just curious how I could read the arrays from a function.

scanf(), fgets(), fgetc()
http://faq.cprogramming.com/cgi-bin/...&id=1043284392

Something is wrong with my functions but I havent been able to find a good resource to help me out. I am getting errors saying my customer and balance array are unrefereneced. Any help would be appreciated

Code:

 
#include <iostream>
#include <fstream>
#include <iomanip>
#include <cmath>

using namespace std;

void headings(ofstream &outFile);
void readData(ifstream &inFile);
void sort(ifstream &inFile);

int main()
{
	const int size = 50;
	
	//declare variables
	int customer[size];
	double balance[size];
	
	//open files
	ifstream inFile;
	ofstream outFile;
	inFile.open("prog7.txt");
	outFile.open("prog7.out");

	headings(outFile);
	
	// read from file
	double temp = 0;
	readData(inFile);
	while (!inFile.eof())
{
	readData(inFile);
	temp ++;
}
	sort(inFile);
	outFile.close();
	inFile.close();
	return 0;
}
	void headings(ofstream &outFile)
	{
		
		outFile <<setw(10)<< "Customer ID"
				<<setw(10)<< "Balance"
				<<endl;
	}
	void readData(ifstream &inFile)
		{
			double temp = 0;
			inFile >> customer[temp] >> balance[temp];
		}
	void sort(ifstream &inFile)
		{
        	for(int j=1; j< size; j++)
			{
				for(int i=0; i< size-1; i++)
				{
					if(balance[i] > balance[i+1]
					{
						temp=balance[i];
						balance[i]=balance[i+1];
						balance[i+1]=temp;
					}
				}
			}
		}
	void printResults(ofstream &outFile, ifstream &inFile)
		{
			outFile << setprecision(2) << fixed << showpoint;
			outFile <<setw(10)<< customer[size]
					<<setw(10)<< balance[size]
					<<endl << endl;
		}

You need to pass them to the functions. customer is declared in main so only main can see it.
IE:

Code:

void readData(ifstream &inFile, int customer[], double balance[])
{
double temp = 0;
inFile >> customer[temp] >> balance[temp];
}

which then would be called with:

Code:

readData(inFile, customer, balance);

However that function has an error in that temp is a double but you are using it as the index to an array

Hi. I get a bunch of compile-time errors with your code. Be careful:

Code:

    if(balance[i] > balance[i+1]

You haven't closed the parenthesis of the if conditional.
Correct:

Code:

    if(balance[i] > balance[i+1])
    {
        /*...*/
    }

Good Luck,
Steve

ok thanks for the help so far. I cleaned up the code and managed to get no errors after debugging, but still am not getting any output. Not sure how to add reference variables to arrays while in a function. Any help on how to do this or what my problem might be would be greatly appreciated.

Code:

#include <iostream>
#include <fstream>
#include <iomanip>
#include <cmath>
#define size 50

using namespace std;

void headings(ofstream &outFile);
void readData(ifstream &inFile, int customer[], float balance[]);
void sort(ifstream &inFile, float balance[]);
void printResults(ofstream &outFile, ifstream &inFile, int customer[], float balance[]);

int main()
{
	//declare variables
	int customer[size];
	float balance[size];
	
	//open files
	ifstream inFile;
	ofstream outFile;
	inFile.open("prog7.txt");
	outFile.open("prog7.out");

	// funtion to print headings
	headings(outFile);
	
	// read from file
	float temp = 0;
	readData(inFile, customer, balance);
	
	// loop
	while (!inFile.eof())
	{
		readData(inFile, customer, balance);
		temp ++;								
	}
	
	// function to sort in descending order
	sort(inFile, balance);

	// function to print results
	printResults(outFile, inFile, customer,  balance); 


	outFile.close();
	inFile.close();
	return 0;
}
	void headings(ofstream &outFile)
	{
		outFile <<setw(10)<< "Customer ID"
				<<setw(10)<< "Balance"
				<<endl;
	}
	void readData(ifstream &inFile, int customer[], float balance[]) 
		{
			static int i = 0;			  
			static int j = 0;
			inFile >> customer[j] >> balance[i];
		}
	void sort(ifstream &inFile, float balance[])
		{
			float temp = 0;			
        	for(int j=1; j< size; j++)
			{
				for(int i=0; i< size-1; i++)
				{
					if(balance[i] > balance[i+1])
					{
						temp=balance[i];
						balance[i]=balance[i+1];
						balance[i+1]=temp;
					}
				}
			}
		}
	void printResults(ofstream &outFile, ifstream &inFile, int customer[], float balance[])
		{
			outFile << setprecision(2) << fixed << showpoint;
			outFile <<setw(10)<< customer
					<<setw(10)<< balance
					<<endl << endl;
		}