ifstream help

Hey guys,

I'm trying to learn c++, but i think i may need a little help at this point.
I want to read some data from a file "test.dat", but for some reason it won't work.
I don't see where i mess up, maybe you can help me.

thanks

Code:

#include <iostream>
#include <fstream>

using namespace std;

int main() {

// Open the file 
 ifstream infile("test.dat", ios::in | ios::nocreate);

// Check
 if (!infile.good()) {
  cout << "Error" << endl << endl;
  system("PAUSE");
  exit(1);
 }

 double value, type1, type2, type3, type4, type5;

// Read the data
   infile >> value >> type1 >> type2 >> type3 >> type4 >> type5;
   while (value!=-1) {
    infile >> value >> type1 >> type2 >> type3 >> type4 >> type5;
    cout << value << "\t" << type1 << "\t" << type2 << "\t" 
         << type3 << "\t" << type4 << "\t" << type5 << endl;
   }

 system("PAUSE");
 return(0);
}

Mmkay, "won't work" doesn't tell us anything.

What's the actual problem? infile.good() returns false? You don't get the data in the right order?

Try to be a little more specific as to what you expect the program to do and what it is actually doing instead.

And lastly, welcome to cboard.

I'm sorry, forgot a bit i see

The first problem is the bit

Code:

ifstream infile("test.dat", ios::in | ios::nocreate);

It won't compile until i delete the "ios::nocreate" part. It says:
'nocreate' is not a member of 'std::ios'
When i delete this part, it will compile without complaining.

The main problem is indeed that infile.good() returns false and thus displays the error message

I'm using Bloodshed Dev-c++ 4.9.9.2

I do not believe ios::nocreate is standard, so you should probably leave it out.

As far as it failing, are you sure that test.dat is located in the working directory of your program? By default that will be the same folder as your program (ie. the exe file).

http://www.devx.com/tips/Tip/14544

Yes, test.dat is located in the same directory as my *.cpp file and thus the executable.

Did i forget any headers or something?

Does something like this behave as expected?

Code:

#include <iostream>
#include <fstream>
#include <cstdlib>
#include <cstdio>

using namespace std;

int main()
{
   static const char filename[] = "test.dat";

   // Open the file 
   ifstream infile(filename);

   // Check
   if ( !infile.good() )
   {
      perror(filename);
      system("PAUSE");
      exit(EXIT_FAILURE);
   }

   double value, type1, type2, type3, type4, type5;

   // Read the data
   while ( (infile >> value >> type1 >> type2 >> type3 >> type4 >> type5) &&
           value!=-1 )
   {
      cout << value << "\t" << type1 << "\t" << type2 << "\t" 
           << type3 << "\t" << type4 << "\t" << type5 << endl;
   }

   system("PAUSE");
   return 0;
}

Originally Posted by JustMe

Yes, test.dat is located in the same directory as my *.cpp file and thus the executable.

Did i forget any headers or something?

Nope. Your headers are fine I believe.

Code:

system("dir");

Try adding that just for now in your program, and see if test.dat is located in the output.

Hey guys,

Thanks for the help, the last post gave me the problem.
I'm also running a fresh windows install and windows hides the file extensions by default.

I thought i wrote a file "test.dat" in notepad, but actually wrote a file "test.dat.txt"

thanks again for helping out