#include <stdio.h>
typedef int ElementType;
#define NotFound (-1)
/* START: fig2_9.txt */
int
BinarySearch( const ElementType A[ ], ElementType X, int N )
{
int Low, Mid, High;
/* 1*/ Low = 0; High = N - 1;
/* 2*/ while( Low <= High )
{
/* 3*/ Mid = ( Low + High ) / 2;
/* 4*/ if( A[ Mid ] < X )
/* 5*/ Low = Mid + 1;
else
/* 6*/ if( A[ Mid ] > X )
/* 7*/ High = Mid - 1;
else
/* 8*/ return Mid; /* Found */
}
/* 9*/ return NotFound; /* NotFound is defined as -1 */
}
/* END */
main( )
{
static int A[ ] = { 1, 3, 5, 7, 9, 13, 15 };
const int SizeofA = sizeof( A ) / sizeof( A[ 0 ] );
int i;
for( i = 0; i < 20; i++ )
printf( "BinarySearch of %d returns %d\n",
i, BinarySearch( A, i, SizeofA ) );
return 0;
}
