binary search program in c code example

Example 1: binary search program c++

#include <iostream>
using namespace std;

// This program performs a binary search through an array, must be sorted to work
int binarySearch(int array[], int size, int value) 
{   
    int first = 0,         // First array element       
    last = size - 1,       // Last array element       
    middle,                // Mid point of search       
    position = -1;         // Position of search value   
    bool found = false;        // Flag   
    while (!found && first <= last) 
    {      
        middle = (first + last) / 2;     // Calculate mid point      
        if (array[middle] == value)      // If value is found at mid      
    	{         
                found = true;         
                position = middle;      
        }      
        else if (array[middle] > value)  // If value is in lower half         
            last = middle - 1;      
        else         
            first = middle + 1;          // If value is in upper half   
    }   
    return position;
}
int main ()
{
    const int size = 5; // size initialization
    int array[size] = {1, 2, 3, 4, 5}; // declare array of size 10
    int value; // declare value to be searched for
    int result; // declare variable that will be returned after binary search

    cout << "What value would you like to search for? "; // prompt user to enter value
    cin >> value;
    result = binarySearch(array, size, value);

    if (result == -1) // if value isn't found display this message
        cout << "Not found\n";
    else  // If value is found, displays message
        cout << "Your value is in the array.\n"; 
  
    return 0;
}

Example 2: binary search in c++

#include<iostream> 
using namespace std; 
int binarySearch(int arr[], int p, int r, int num) { 
   if (p <= r) { 
      int mid = (p + r)/2; 
      if (arr[mid] == num)   
         return mid ; 
      if (arr[mid] > num)  
         return binarySearch(arr, p, mid-1, num);            
      if (arr[mid] < num)
         return binarySearch(arr, mid+1, r, num); 
   } 
   return -1; 
} 
int main(void) { 
   int arr[] = {1, 3, 7, 15, 18, 20, 25, 33, 36, 40}; 
   int n = sizeof(arr)/ sizeof(arr[0]); 
   int num = 33; 
   int index = binarySearch (arr, 0, n-1, num); 
   if(index == -1)
      cout<< num <<" is not present in the array";
   else
      cout<< num <<" is present at index "<< index <<" in the array"; 
   return 0; 
}

Example 3: binary search in c

//C Implementation
#include<stdio.h>
int BinarySearch(int arr[], int search, int mid, int len){
    if(mid == -1 || mid == len+1){
        printf("\nSearched Element doesn't exist.");
        return 1;
    }
    else if (search > arr[mid]){
        mid++;
        BinarySearch(arr,search,mid,len);
        return 0;
    }
    else if (search < arr[mid]){
        mid--;
        BinarySearch(arr,search,mid,len);
        return 0;
    }
    else if(search == arr[mid]) {
        printf("\n Searched Element found at Location %d.",mid);
        return 1;
    } 
}
void main(){
    int arr[] = {1,2,3,4,5,6,7,8,9};
    int len = sizeof(arr) / sizeof(int);
    int mid = (int) (len / 2) + 1;
    printf("\n Please Enter Number You Want to Search \n >  ");
    int search;
    scanf("%d",&search);
    int Result = BinarySearch(arr,search,mid,len);
}