binary seach in decending order

Posted: Sun Nov 09, 2003 2:56 am    Post subject: Descending search
elements   

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I am trying to do this search code in decending order with it not
losing any of the functons. Here's my code. 
[/code] 
#include <iostream> 

using std::cout; 
using std::cin; 
using std::endl; 

#include <iomanip> 

using std::setw; 

// function prototypes 
int binarySearch( const int [], int, int, int, int ); 
void printHeader( int ); 
void printRow( const int [], int, int, int, int ); 

int main() 
{ 
const int arraySize = 15; // size of array a 
int a[ arraySize ]; // create array a 
int key; // value to locate in a 

for ( int i = 0; i < arraySize; i++ ) // create some data 
a[ i ] = 2 * i; 

cout << "Enter a number between 0 and 28: "; 
cin >> key; 

printHeader( arraySize ); 

// search for key in array a 
int result = 
binarySearch( a, key, 0, arraySize - 1, arraySize ); 

// display results 
if ( result != -1 ) 
cout << '\n' << key << " found in array element " 
<< result << endl; 
else 
cout << '\n' << key << " not found" << endl; 

return 0; // indicates successful termination 

} // end main 

// function to perform binary search of an array 
int binarySearch( const int b[], int searchKey, int low, 
int high, int size ) 
{ 
int middle; 

// loop until low subscript is greater than high subscript 
while ( low <= high ) { 

// determine middle element of subarray being searched 
middle = ( low + high ) / 2; 

// display subarray used in this loop iteration 
printRow( b, low, middle, high, size ); 

// if searchKey matches middle element, return middle 
if ( searchKey == b[ middle ] ) // match 
return middle; 

else 

// if searchKey less than middle element, 
// set new high element 
if ( searchKey < b[ middle ] ) 
high = middle - 1; // search low end of array 

// if searchKey greater than middle element, 
// set new low element 
else 
low = middle + 1; // search high end of array 
} 

return -1; // searchKey not found 

} // end function binarySearch 

// print header for output 
void printHeader( int size ) 
{ 
cout << "\nSubscripts:\n"; 

// output column heads 
for ( int j = 0; j < size; j++ ) 
cout << setw( 3 ) << j << ' '; 

cout << '\n'; // start new line of output 

// output line of - characters 
for ( int k = 1; k <= 4 * size; k++ ) 
cout << '-'; 

cout << endl; // start new line of output 

} // end function printHeader 

// print one row of output showing the current 
// part of the array being processed 
void printRow( const int b[], int low, int mid, 
int high, int size ) 
{ 
// loop through entire array 
for ( int m = 0; m < size; m++ ) 

// display spaces if outside current subarray range 
if ( m < low || m > high ) 
cout << " "; 

// display middle element marked with a * 
else 

if ( m == mid ) // mark middle value 
cout << setw( 3 ) << b[ m ] << '*'; 

// display other elements in subarray 
else 
cout << setw( 3 ) << b[ m ] << ' '; 

cout << endl; // start new line of output 

} // end function printRow 
 
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 Posted: Sun Nov 09, 2003 4:16 am    Post subject: Descending search
elements   

--------------------------------------------------------------------------------
 
In almost all cases searches and sorting are done ascending. I have
tried chnaging some things to create different values but I tend to
loose some of the functions.  
 




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