#include<iostream.h>
#include<fstream.h>

// Burton Rosenberg
// September 4, 1997
// MaxInteger.C

// =================================================

/* 
   readFile:
   Input: an array of integers, the size of the array
          and a file name
   Returns: number of integers read into the array,
          or -1 if error
*/

int readFile ( 
   int * destinationArray,
   int arraySize,   
   char * filename )
{
   ifstream inFile ;
   int i ;

   // Read from the file
   inFile.open( filename ) ;
   if ( !inFile ) {
      cout << "Could not open " << filename << endl ;
      return -1 ;
   }
   i = 0 ;
   while ( i<arraySize  // check for array overflow first
           && inFile>>destinationArray[i] ) {
      i++ ;
   }

   inFile.close() ;  
   return i ;
}

// =======================================================

/* findMaxByIndex:
   Input: array of integers, length of array
   Output: index i of maximum integer in the array.
*/

int findMaxByIndex( 
   int * a, 
   int n )
{
   if ( n<1 ) return -1 ;

   // ASSERT: array is not empty.
   
   int biggest = 0 ;
   int top = 1 ;
   // LOOP INVARIANT: for i=0, ..., top-1,
   //   a[biggest] is the max integer.
   while ( top<n ) {
      if ( a[top] > a[biggest] ) { 
         biggest = top ;
      }
      top ++ ;
      // ASSERT: Loop Invariant
   }
   // POSTCONDITION: a[biggest] largest in entire array.

   return biggest ;
}

// ===========================================================

int main(
   int argc, 
   char * argv)
{

   const int ARRAY_SIZE = 1000 ;
   int a[ARRAY_SIZE] ;

   int aSize = readFile(a, ARRAY_SIZE, "myFile.txt") ;
   if ( aSize < 0 ) return 0 ;  

   int maxIntAtIndex = findMaxByIndex( a, aSize ) ;
   cout << "Maximum integer is " 
        << a[maxIntAtIndex] 
        << "." << endl ;

   return 0 ;
  
}