Insertion sort... Please help!

So for an assignment I'm supposed to have my insertion sort program take numbers from a file (in this case infile.txt) and sort them using insertion sort then output the array.

This is what I currently have:

Code:

---

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


int main()
{
  ifstream fin("infile.txt");
  int a[6], length, number, i;
        for(int j=1;j<length;j++)
        {
        number=a[j];
        i=j-1;
                while(a[i]>number && i>=0)
                {
                        a[i+1]=a[i];
                        i--;
                }
        a[i+1]=number;
        }

  cout << a[i] << "\n";
  return 0;
}

---

When the infile.txt file lists the numbers:
5
6
98
7
5
6
1
8
6
4

However, as an output I am just getting the number 13... Does anyone know why this would be and how I would go about fixing it?
THANK YOU SO MUCH!!!!!!!!!!!

im not good at programming much and im not familiar with file i/o but where are you recording the numbers from the file

you need to fill int a[6], length, number, i, with some values before you can use them. (eg. by taking input from fin)

and im guessing you would get a different number besides 13 everytime, maybe idk or no output

Quote:

---

Originally Posted by cyberfish

you need to fill int a[6], length, number, i, with some values before you can use them. (eg. by taking input from fin)

---

Do you mean like declare length = to a specific number?

i dont know the syntax or anything but get all those numbers from the file stream into int array!

I'll have to google that one :-p

Ok well I dont really get wut u want to do... But if you wanna read in a file and put the values in an array here is a simple way to do it :

Code:

---

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

int main(int argc, char *argv[])
{
        string filename="file";
        int numbers;
        vector <int> array; 
         
          ifstream Read;
          Read.open(filename.c_str());
 
          if(Read.fail())
        {
                      cerr << "Error couldnt open the file" << filename << endl;
                      exit(EXIT_FAILURE);
          }
                 
          while(Read >> numbers)
          {
                      array.push_back(numbers);       
          }
 
          for(int i=0;i<array.size();i++)
          {
                  cout << array[i]<<endl;
          }

              Read.close();
return 0;
}

---

And about sorting em... I dont get what you want to do...

he is trying to sort those numbers in order using "insertion" method,,there are a couple other methods

i remember learning about them back in high school, i dont remember if that was the efficient method but w/e

http://en.wikipedia.org/wiki/Insertion_sort

The first problem is that you're not actually reading anything in from the file.
The second problem is that you're only outputting one number (you need a loop to output them all).

The sorting algorithm itself looks correct, from memory.

Also, if you want to sort 10 numbers, you probably need an array bigger than 6?

--
Mats