DaniWeb Forum Index > Software Development > C++

C++ RSS

Basic File I/O problem

Please support our C++ advertiser: Intel Parallel Studio Home

•

Join Date: Feb 2004

Posts: 1

Reputation: Jeannie is an unknown quantity at this point

Solved Threads: 0

Jeannie

Offline

Newbie Poster

Basic File I/O problem

Feb 16th, 2004

I'm pretty new at C++ and I have a problem with a program that opens a file with a list of numbers and finds the median. My problem is, no matter what numbers are in the file, it always says the median is 1. I've been able to tell it what position the median is in, but I can't get it to return the number that's in that position. How can I get it to reopen the file, find the median number, and spit it back to me?

Attached is what I've done so far.
Here is what the data file is uses looks like:
file2.dat
1
2
3
4
5
6
7
8

I know the simplicity of it is laughable, but bear with me. I'm a newbie.

Attached Files

median2.cpp (840 Bytes, 21 views)

•

Join Date: Feb 2003

Posts: 129

Reputation: Bob is an unknown quantity at this point

Solved Threads: 1

Bob

Offline

Team Member

Re: Basic File I/O problem

Feb 18th, 2004

Hi, don't worry, it's not laughable, we've all been equally as stumped with problems equally as simple once upon a time.

Having calculated which position the median is at, you then reopen the file, read in the first value from the file, and output this as the median. The first value in the file is 1, so the program always outputs this as the median, even though it's not the value in the median position.

You need to read in values until you've reached the one at the median position, rather than just reading in the first value.

Hope that helps.

•

Join Date: Jun 2005

Posts: 1

Reputation: Big_D is an unknown quantity at this point

Solved Threads: 0

Big_D

Offline

Newbie Poster

Re: Basic File I/O problem

Jun 19th, 2005

how do u save an array into a file?

•

Join Date: May 2005

Posts: 232

Reputation: Dogtree is an unknown quantity at this point

Solved Threads: 3

Dogtree

Offline

Posting Whiz in Training

Re: Basic File I/O problem

Jun 19th, 2005

Dude, this thread is well over a year old. Next time, if you have a new question, start a new thread.

To save an array to file, just open the file, then loop over the array and write each element in turn:

 Help with Code Tags 
 C++ Syntax (Toggle Plain Text) 
#include <fstream>
 
int main()
{
  std::ofstream out("somefile");
  int array[] = {0,1,2,3,4,5,6,7,8,9};
 
  if (out.is_open()) {
    for (int i = 0; i < 10; i++)
      out << array[i];
  }
}
#include <fstream>

int main()
{
  std::ofstream out("somefile");
  int array[] = {0,1,2,3,4,5,6,7,8,9};

  if (out.is_open()) {
    for (int i = 0; i < 10; i++)
      out << array[i];
  }
}