There are numerous algorithms that allow you to manipulate the information stored in an array.  Consider this function which allows you to determine the maximum value in an array of integers (could be easily adapted to find minimum value):

//Function to find highest (maximum) value in array
int maximumValue(apvector<int> &array)
{
     int length = array.length( );  // establish size of array
     int max = array[0];       // start with max = first element

     for(int i = 1; i<length; i++)
     {
          if(array[i] > max)
                max = array[i];
     }
     return max;                // return highest value in array
}