reading data from files, file name as input

Question

Hey, I am writing a program which reads data from different files, which are given as input strings, and stores them into a vector of vectors. The problem I am not able to debug the loop which reads different files. I have closed the ifstream object, cleared the string using empty function... but still it just terminates when i give second file name as input.

I am copying the code for your perusal. It is a function called by another another function. Transposectr transposes a matrix.

code:

vector<vector<float> > store1,store2;
ifstream bb;

string my_string;

float carrier;
vector<float> buffer;

cout<<"enter the file name"<<endl;
getline(cin,my_string);

while (my_string!="end")

{

bb.open(my_string.c_str());
while (!bb.eof())
{
 bb >> carrier;

 if (bb.peek() == '\n' || bb.eof() )
 {
  buffer.push_back(carrier);
  store1.push_back(buffer);
  buffer.clear();
 }

 else
 {
  buffer.push_back(carrier);
 }


}

bb.close();
buffer.clear();
transposectr1(store1);
storex.push_back(store1[1]);
storey.push_back(store1[0]);
store1.clear();
my_string.empty();
cout<<"done reading the file"<<endl;
cout<<"enter the file name"<<endl;
getline(cin,my_string);

}

Answer 1

I'm really not clear what you are trying to do. But I have one golden ruile when it comes to using istreams:

Never use the eof() function!

It almost certainly does not do what you think it does. Instead you should test if a read operation succeeded.

int x;

while( in >> x ) {
   // I read something successfully
}

You might also want to avoid peek() too. Try re-writing your code with this advice in mind.

Answer 2

Add

bb.clear();

after the bb.close() you may get the right thing. bb.close() doesn't reset the cursor I think.

Answer 3

Neil Butterworth is right

Never use the eof() function!

This link explains why.