#include <iostream>
#include <iomanip>
#include <vector>
#include <fstream>
using namespace std;

struct datastring
{
  int studentNum;
  string studentName;
  double OB; //outstanding balance
};

int main()
{
  int size = 2;
  vector<datastring> myVec(2);
  ifstream FI;

  FI.open("students.dat");
  if (FI.fail())
  {
  cerr<<"File failed to open, create it."<<endl;
     abort();
  }

  FI >> myVec.studentNum;
  while(!FI.eof())
  {
     cin.ignore();
     cin.getline(FI, myVec.studentName);
     FI >> myVec.OB;
     if (myVec.size() >= size)
     {
        myVec.resize(2*size);
     }
     FI >> myVec.studentNum;
  }

  cout<<"Works"<<endl;
  FI.close();
  return 0;
}

 

The main focus is when I'm trying to read in information from a file into a vector, and it just can't seem to work with my struct. The task is to learn dynamic allocation, and that's why there's a resize function. The rest is cake once I get this resolved.

 

Any help is appreciated.

http://www.cplusplus.com/reference/stl/vector/

 

You don't resize vectors as that is handled automatically by the container.

You add objects to vectors using push_back or push_front usually. Theres also methods for inserting.

myVec.push_back(datastring);

 

You should also consider reading up on the other types of containers since they all have advantages and disadvantages.

http://www.cplusplus.com/reference/stl/

http://pastebin.com/uUsEAEPH

 

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

using namespace std;

struct studentData
{
int ID;
string firstName;
string lastName;
double outstandingBalance;
};

int main()
{
vector<studentData> vecStudentData;
ifstream fileInput;

fileInput.open("students.dat", ifstream::in);
if(fileInput.fail())
{
	cout << "File failed to open" << endl;
	return 1;
}

studentData temp;
while(fileInput.good())
{
	fileInput >> temp.ID
			  >> temp.firstName
			  >> temp.lastName
			  >> temp.outstandingBalance;

	vecStudentData.push_back(temp);
}

fileInput.close();

for(unsigned int i = 0; i < vecStudentData.size(); i++)
{
	cout << i << " " << vecStudentData[i].ID
			  << " " << vecStudentData[i].firstName
			  << " " << vecStudentData[i].lastName
			  << " " << vecStudentData[i].outstandingBalance << endl;
}
}

 

This assumes a .dat layout with each var seperated by whitespace.

eg/

ID FIRSTNAME LASTNAME OB ID FIRSTNAME LASTNAME OB...

ID FIRSTNAME LASTNAME OB
ID FIRSTNAME LASTNAME OB
...

ID
FIRSTNAME
LASTNAME
OB
...

 

I hate files :(