returning dynamic array from function

[bushnellweb]

The output for newInfo[0] is blank. it should be the record number

string *changeData(string arr[][4],int records)
{
	string newInfo[5];
	stringstream ss;
	ss << recordSelected;
	newInfo[0] = ss.str();
	
	cin.ignore(1);
	cout << "New ID: ";
	getline(cin,newInfo[1]);
	cout << "New DESC: ";
	getline(cin,newInfo[2]);
	cout << "New COST: ";
	getline(cin,newInfo[3]);
	cout << "New SUPPLY: ";
	getline(cin,newInfo[4]);

	string *arr2 = newInfo;

	system("pause");

	return(arr2);
}

int main()
{
    int c = countRecords(fileName,false);//  c=2
    string (*p)[4] = new string[c][4];

     string newInfo[5] = {*changeData(p,c)};

cout << newInfo[0] << endl; // [B]Output is blank[/B]
}

[newb16]

Returning a pointer to a local variable (in this case, string) is not good - it may be overwritten in any time after return.

[johny10151981]

Try debugging your software with the associate debugger.

By the way what is this line?
ss << recordSelected;

what is var type of recordSelected. I dont know how

ss << recordSelected;. If recordSelected is any kind of number(int, long) type variable and ss is string then check whether this line work at all..

[weaknessforcats]

Why not use a vector instead of all this array stuff? All the vector is is an array that has the control code already written and debugged so you don't have to do it over and over and over for your own arrays.

[bushnellweb]

hmm I never learned vectors..I guess I will have to look into it

[weaknessforcats]

If you can use an array, you can use a vector. vector is required to be implemented as an array.

vector<int> arr;              //create rthe array
arr.push_back(2);          //add 2 to the end of the array
cout << arr[0];              //display the 2.

It's not too hard.

[bushnellweb]

@weaknessforcat s - thanks man that really helps, wasn't too hard to figure out mutli-dim vectors.

[bushnellweb]

another problem

I switched my app to vectors and got this error already. any ideas?

error: debug assertion failed! expression: vector subscript out of range

#include <iostream>
#include <string>
#include <fstream>
#include <new>
#include <iomanip>
#include <sstream>
#include <vector>

using namespace std;


/*
	function: countRecords
	params: string fileName, bool outputTF
	purpose: counts records from passed file name and outputs data if bool is true
*/
int countRecords(string fileName, bool outputTF)
{
	ifstream inFile;
	int recordCount = 0;

	inFile.open(fileName.c_str(),ios::in);
	if(inFile.is_open())
	{
		//priming read
		inFile.ignore(1000,'\n');
		recordCount = 1;

		//loop
		while(!inFile.eof())
		{
			inFile.ignore(1000,'\n');
			recordCount++;
		}

		if(outputTF == true)
		{
			cout << "recordCount= " << recordCount << endl;
		}
		
	}else{ cout << "File would not open!" << endl; }
	inFile.close();

	return recordCount;
}

// ***************** MAIN PROCEDURE ***********************
int main()
{
	const int fields = 4; //creates constant int of 4 fields (number of fields doesn't usually change)
	const char fieldDel = '_'; //creates constant char for field delimeter
	string fileName = "data1.dat"; //define fileName
	int c = countRecords(fileName,false); //define number of records in data1.dat

	vector <vector<string>> vec1; //create 2 dimensional vector

	ifstream inFile; //define ifstream as inFile - lets data from data1.dat into the app
	inFile.open("data1.dat",ios::in); //opens inFile for reading
	if(inFile.is_open()) //only do actions to inFile if file actually opens
	{
		while(!inFile.eof()) //only do actions while inFile is not at EOF
		{
			vector <string> rowVec; //creates temporary vector for adding to main vector
			for(int i=0; i<c; i++) //loops through records
			{
				for(int t=0; t<fields; t++) //loops through # of fields
				{
					if(t == fields-1) //if t is equal to fields-1 then read until '\n' instead of field delimeter
					{
						getline(inFile,rowVec[t],'\n');
						vec1.push_back(rowVec); //pushes rowVec into multi-dim vector
					}else{
						getline(inFile,rowVec[t],fieldDel);
					} //end if(t == fields-1)
				}// end field loop
			} //end record loop
		} //end while(!inFile.eof())
	} //end if(inFile.is_open())

	





return 0; //return 0
}

[Banfa]

Yes at some point while running your code you tried to access an index in the vector that was beyond its size.

Your best option is to running it in a debugger, the assurtion should cause the debugger to halt when the error happens and you will be able to see what has happened by examining the call stack.

[bushnellweb]

whats a good debugger?

[bushnellweb]

oh you know what I think its because I am doing

getline(inFile, rowVec[t],'\n');

and rowVec[t] hasn't been defined yet. I need to push_back the data. not getline

[Banfa]

Indeed one of the basic rules of programming that.

If the data in an object is worth examining then its worth populating.