binary search function in c 2b 2b

1#include <iostream>
2using namespace std;
3
4// This program performs a binary search through an array, must be sorted to work
5int binarySearch(int array[], int size, int value) 
6{   
7    int first = 0,         // First array element       
8    last = size - 1,       // Last array element       
9    middle,                // Mid point of search       
10    position = -1;         // Position of search value   
11    bool found = false;        // Flag   
12    while (!found && first <= last) 
13    {      
14        middle = (first + last) / 2;     // Calculate mid point      
15        if (array[middle] == value)      // If value is found at mid      
16    	{         
17                found = true;         
18                position = middle;      
19        }      
20        else if (array[middle] > value)  // If value is in lower half         
21            last = middle - 1;      
22        else         
23            first = middle + 1;          // If value is in upper half   
24    }   
25    return position;
26}
27int main ()
28{
29    const int size = 5; // size initialization
30    int array[size] = {1, 2, 3, 4, 5}; // declare array of size 10
31    int value; // declare value to be searched for
32    int result; // declare variable that will be returned after binary search
33
34    cout << "What value would you like to search for? "; // prompt user to enter value
35    cin >> value;
36    result = binarySearch(array, size, value);
37
38    if (result == -1) // if value isn't found display this message
39        cout << "Not found\n";
40    else  // If value is found, displays message
41        cout << "Your value is in the array.\n"; 
42  
43    return 0;
44}

1// BY shivam kumar KIIT
2#include<bits/stdc++.h>
3usind namespace std;
4int main()
5{
6	int arr[]={10,2,34,2,5,4,1};
7  	sort(arr,arr+7);//sort array in ascending order before using binary search
8  	binary_search(arr,arr+7,10);//return 1 as element is found
9  	binary_search(arr,arr+7,3);//return 0 as element is not found
10  	return 0;
11}

1#include<iostream> 
2using namespace std; 
3int binarySearch(int arr[], int p, int r, int num) { 
4   if (p <= r) { 
5      int mid = (p + r)/2; 
6      if (arr[mid] == num)   
7         return mid ; 
8      if (arr[mid] > num)  
9         return binarySearch(arr, p, mid-1, num);            
10      if (arr[mid] < num)
11         return binarySearch(arr, mid+1, r, num); 
12   } 
13   return -1; 
14} 
15int main(void) { 
16   int arr[] = {1, 3, 7, 15, 18, 20, 25, 33, 36, 40}; 
17   int n = sizeof(arr)/ sizeof(arr[0]); 
18   int num = 33; 
19   int index = binarySearch (arr, 0, n-1, num); 
20   if(index == -1)
21      cout<< num <<" is not present in the array";
22   else
23      cout<< num <<" is present at index "<< index <<" in the array"; 
24   return 0; 
25}

1#include<iostream>
2using namespace std;
3int binarySearch(int arr[], int p, int r, int num) {
4   if (p <= r) {
5      int mid = (p + r)/2;
6      if (arr[mid] == num)
7      return mid ;
8      if (arr[mid] > num)
9      return binarySearch(arr, p, mid-1, num);
10      if (arr[mid] > num)
11      return binarySearch(arr, mid+1, r, num);
12   }
13   return -1;
14}
15int main(void) {
16   int arr[] = {1, 3, 7, 15, 18, 20, 25, 33, 36, 40};
17   int n = sizeof(arr)/ sizeof(arr[0]);
18   int num = 33;
19   int index = binarySearch (arr, 0, n-1, num);
20   if(index == -1)
21   cout<< num <<" is not present in the array";
22   else
23   cout<< num <<" is present at index "<< index <<" in the array";
24   return 0;
25}

1//requires header <algorithm> for std::binary_search
2#include <algorithm>
3#include <vector>
4
5bool binarySearchVector(const std::vector<int>& vector,
6                       	int target) {
7  //this line does all binary searching
8  return std::binary_search(vector.cbegin(), vector.cend(), target);
9}
10
11#include <iostream>
12
13int main()
14{
15    std::vector<int> haystack {1, 3, 4, 5, 9};
16    std::vector<int> needles {1, 2, 3};
17 
18    for (auto needle : needles) {
19        std::cout << "Searching for " << needle << std::endl;
20        if (binarySearchVector(haystack, needle)) {
21            std::cout << "Found " << needle << std::endl;
22        } else {
23            std::cout << "no dice!" << std::endl;
24        }
25    }
26}

1//By Sudhanshu Sharan
2#include<iostream>
3#include<cmath>
4using namespace std;
5// BCT= o(1)  and  WCT=O(logn)   time taken for unsucessful search is always o(logn)
6
7int BinSearch( int arr[],int key,int len)
8{
9	int h,mid,l;
10	l=0;
11	h=len-1;
12	while(l<=h)
13	{
14		mid=((l+h)/2);
15		if(key==arr[mid])
16			return mid;
17		else if(key<arr[mid])
18			h=mid-1;
19		else
20			l=mid+1;
21	}
22	return -1;
23}
24int main()
25{
26	int key,i,len;
27	int arr[] = {1,2,3,6,9,12,15,34,54};
28	len=sizeof(arr)/sizeof(arr[0]);
29	cout<<"enter the key to be searched";
30	cin>>key;
31	int result= BinSearch(arr,key,len);
32	(result == -1)
33		? cout<<"Element is not present in the array"<<endl
34		: cout<<"Element is present at index : "<<result<<endl;	
35	for(i=0;i<len-1;i++)
36		cout<<arr[i]<<" ";
37    return 0;
38}