Program 11

BINARY SEARCH

Write a C++ program to accept a single dimensional array and search for an element by Binary search.

#include<iostream.h>

#include<conio.h>

int bsearch(int[],int,int);

void main()

{

  clrscr();

  int a[50],item,n,index;

  cout<<"Enter array size ";

  cin>>n;

  cout<<"\nEnter array elements :";

  for(int i=0;i<n;i++)

          cin>>a[i];

  cout<<"\nEnter an element to be searched for";

  cin>>item;

  index = bsearch(a,n,item);

  if(index==-1)

cout<<"Given element not found";

 else

cout<<"\nElement found at index :"<<index<< ", position  :"<<index+1<<endl;

  getch();

 }

int bsearch(int a[],int size, int item)

{

          for(int i=0;i<size;i++)

{

int beg,last,mid;

beg=0,last=size-1;

while(beg<=last)

{

mid=(beg+last)/2;

if(item==a[mid])

return mid;

else if(item<a[mid])

beg=mid+1;

else

last=mid-1;

}

return i;

}

return -1;

}