Binary search of an array


Levels of difficulty: / perform operation:


Program

#include <stdio.h>
#define SIZE 15

int binarySearch( const int b[], int searchKey, int low, int high );

int main() {
   int a[ SIZE ];
   int i;
   int key = 10;
   int result = -1;

   for ( i = 0; i < SIZE; i++ ) {
      a[ i ] = 2 * i;
   }

   result = binarySearch( a, key, 0, SIZE - 1 );

   if ( result != -1 ) {
      printf( "\n%d found in array element %d\n", key, result );
   } else {
      printf( "\n%d not found\n", key );
   }

   return 0;

}

int binarySearch( const int b[], int searchKey, int low, int high )
{
   int middle;

   while ( low <= high ) {
      middle = ( low + high ) / 2;

      if ( searchKey == b[ middle ] ) {
         return middle;
      } else if ( searchKey < b[ middle ] ) {
         high = middle - 1;
      } else {
         low = middle + 1;
      }
   }
   return -1;

}


Result

10 found in array element 5





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