You really need to be consistent with indenting and spacing. Also, as a newcomer to the language, it's a good idea to put bracket around *every* condition. Here is a cleaned-up version of the code with comments on the remaining problems:
Code:
#include <iostream>
using namespace std;
int main()
{
double
n,
count=0,
sum=0,
min=0, // No, set high.
max=100; // No, set low.
for (;;)
{
if (cin.eof())
{
break;
}
while (cin >> n)
{
if (n < min)
{
min = n;
}
/*
This is wrong - doesn't depend on previous comparison.
*/
else if (n > max)
{
max = n;
}
if (n < 0 || n > 100)
{
cout << "out of range; ignored." << endl;
}
else
{
++count;
sum += n;
/*
This is wrong - calculation needed outside of loop.
Also, 'range' is undeclared.
*/
range = max-min;
}
}
}
/*
Note: cast is unnecessary.
*/
cout << "The average is " << float (sum)/count << endl;
cout << "The range is " << range << endl;
}