Algorithm for binary search in c?

Answer 1

#include<stdio.h>

#include<conio.h>

void main()

{

int a[6],i,data,pos;

clrscr();

printf("enter the element of the array");

for(i=0;i<6;i++)

{

scanf("%d",&a[i]);

}

printf("enter the data for search");

scanf("%d",&data);

for(i=0;i<6;i++)

{

if(a[i]==data)

{

pos=i+1;

break;} }

if(pos==i+1)

printf("position of the element is %d",pos);

else

printf("this is not element in this array ");

getch();

}

( form giriver bisht (future hacker and networking engineer;; if any problem persist u can call me at this no. .. (dehradun 8439881423 )

Answer 2

#include<iostream>

#include<vector>

// returns the index of the given value, or -1 if it does not exist

int bin_search (int val, std::vector<int>& a, int min, int max)

{

// check range for validity

if (max<min)

return -1;

// locate mid-point of sub-array

int mid = min + (max-min) / 2;

// check for equality

if (a[mid] == val)

return mid;

// recurse with appropriate half of sub-array

return val < a[mid] ? bin_search (val, a, min, mid-1) : bin_search (val, a, mid+1, max);

}

// Initiate a binary search. Returns -1 if the value does not exist, otherwise

// returns the index of the given value.

int bin_search(int val, std::vector<int>& a)

{

return bin_search (val, a, 0, a.size()-1);

}

int main()

{

std::vector<int> a = {0, 2, 4, 6, 8, 10, 12, 14, 16, 18};

for (int val=0; val<20; ++val)

{

int i = bin_search (val, a);

if (i==-1)

std::cout << "The value " << val << " does not exist in the array\n";

else

std::cout << "The value " << val << " exists in the array at index " << i << '\n';

}

std::cout << std::endl;

}

Answer 3

1. get the middle element;
2. if the middle element equals to the searched value, the algorithm stops;
3. otherwise, two cases are possible:
   • searched value is less, than the middle element. In this case, go to the step 1 for the part of the array, before middle element.
   • searched value is greater, than the middle element. In this case, go to the step 1 for the part of the array, after middle element.