This C++ program searches the entered number in the list of numbers using **binary search algorithm** and returns the location of the input number if it is found in the list.

## Example: Binary Search Program in C++

**Binary search algorithm** searches the **target value** within a **sorted array**.

- To perform a
**binary search**array must be sorted, it should either be in ascending or descending order. **Step 1:**First**divide**the list of elements in half.**Step 2:**In the second step we compare the target value with the middle element of the array. If it**matches the middle**element then search ends here and**doesn’t proceed further**.**Step 3:**Else if the element less than the middle element then we begin the search in lower half of the array.**Step 4:**Else if the element is greater than the middle element then we begin the search in greater half of the array.**Step 5:**We will repeat the steps 3 ,4 and 5 until our target element is found.

#include <iostream> using namespace std; int binarySearch(int[], int, int, int); int main() { int num[10] = {10, 22, 37, 55, 92, 118}; int search_num, loc=-1; cout<<"Enter the number that you want to search: "; cin>>search_num; loc = binarySearch(num, 0, 6, search_num); if(loc != -1) { cout<<search_num<<" found in the array at the location: "<<loc; } else { cout<<"Element not found"; } return 0; } int binarySearch(int a[], int first, int last, int search_num) { int middle; if(last >= first) { middle = (first + last)/2; //Checking if the element is present at middle loc if(a[middle] == search_num) { return middle+1; } //Checking if the search element is present in greater half else if(a[middle] < search_num) { return binarySearch(a,middle+1,last,search_num); } //Checking if the search element is present in lower half else { return binarySearch(a,first,middle-1,search_num); } } return -1; }

**Output:**

Enter the number that you want to search: 55 55 found in the array at the location: 4

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