Simple Median hekp

I'm trying to find the median in an array and am stuck at the end of my code, obviously grade[median] isn't showing me the grade in the median location, like i'm trying to do. of course, it gives me an error. So what would be the proper way to make it show me the median location in the array? Also, this will only work correct with an odd number of array elements and I know to find the median in an array of even amount of elements, you take the 2 middle terms then divide by 2. Any help on getting the location for the 2 middle terms and dividing by 2?

ps- I know it needs to be sorted first but that is being taken care of by a different person. My job is to come up with the algorithm for finding the median.

Code:

int grade[25];
int i = 0;
float median;



do
{

cout << "Enter grades, to quit enter 999\n";
cin >> grade[i];
i++;
}
while(grade[i-1] != 999);

i = i-1; 



for (int j=0; j<i; j++)
{
cout << grade[j] << endl;
}

median = (i+1) / 2;

cout << grade[median] << endl;

If the sorted sequence has an odd length, take the middle score as the median (length/2). If the length is even, you have to divide the sequence into two parts of equal length, and take the average of the last score in part A and the first score in part B to get the median.

Originally Posted by whiteflags

If the sorted sequence has an odd length, take the middle score as the median (length/2). If the length is even, you have to divide the sequence into two parts of equal length, and take the average of the last score in part A and the first score in part B to get the median.

Thank you, but do you know how to display the score in the [median] spot of the array?

Originally Posted by nick753

Thank you, but do you know how to display the score in the [median] spot of the array?

Once you have found it, you would display it like how you would display any other score.

You need to improve your keyboard input routines. I’ve tidied it up slightly but if you enter a character then your program will crash.

If you reference your grade array with an index > 24 then it will crash, (0 – 24 allowed).

Don’t forget that with integer types, a value of 11 divided by 2 = 5 and not the expected 5.5.

Good luck.

Code:

int grade[25];
int i = 0;
float median;

int x; ///////////////////////

do
{

cout << "Enter grades, to quit enter 999\n";
/////////////////////////////////////////////////////////////cin >> grade[i];
    cin >> x; /////////
    if (x != 999)     ////////////
    {                 //////////
        grade[i] = x;  ////////////////
        i++;           /////////
    }                 /////////

}
////////////////////////////////////////////////////////////while(grade[i-1] != 999);
while ((i < 25) && (x != 999)); //////////////

////////////////////////////////////////////////////////////i = i-1;


for (int j=0; j<i; j++)
{
cout << grade[j] << endl;
}

///////////////////////////////////////////////////////////////median = (i+1) / 2;

//?????????????????????????????????????????????????????????????//cout << grade[median] << endl;


    // to get the 2 required indexes for an even number sequence
    // i = number of integers input
    // a = i / 2
    // b = a + 1
    // median = ((grade[a - 1] + grade[b - 1}) / 2  // -1 because array starts at 0, not 1
    // substitute a and b into:
    // median = (grade[(i / 2) - 1] + grade[((i / 2) + 1) - 1]) / 2
    // median = (grade[(i / 2) - 1] + grade[i / 2]) / 2;

    if (i % 2 == 0) // even number of integers input
    {

    }
    else // odd
    {

    }


    cout << "\Median = " << median << endl;

What is with all the slash nonsense.

If you want to make improvements we might as well use vectors so that proper indexing is almost no work at all.

EDIT: What I posted before was not helpful. This might be moreso.

Code:

#include <cstdlib>
#include <iostream>
#include <cmath>

using namespace std;

int main(int argc, char *argv[])
{
	int grade[25];
	int i = 0;
	float median;

	do
	{
		cout << "Enter grades, to quit enter 999\n";
		cin >> grade[i];
		i++;
	}
        // What if they enter more than 25 grades to be meanies?
	while(grade[i-1] != 999 && i < 25);

	i = i-1; 

       // Sort at some point. I just entered numbers in numerical order because I am nice.

	for (int j=0; j<i; j++)
	{
		cout << grade[j] << endl;
	}

	if(i % 2 == 1)
	{
		median = grade[ (int)floor(i / 2) ];		
	}
	else
	{
		median = 0.5f * ( grade[ (i-1) / 2 ] + grade[ i / 2 ] );
	}

	// Erg, median is declared as float. Try not to index an array with a float type
	//cout << grade[median] << endl;
	cout << median << endl;
}