Binary Search in C++ Standard Template Library (STL)

// CPP program to implement 
// Binary Search in 
// Standard Template Library (STL) 
#include <algorithm> 
#include <iostream> 

using namespace std; 

void show(int a[], int arraysize) 
{ 
	for (int i = 0; i < arraysize; ++i) 
		cout << a[i] << " "; 
} 

int main() 
{ 
	int a[] = { 1, 5, 8, 9, 6, 7, 3, 4, 2, 0 }; 
	int asize = sizeof(a) / sizeof(a[0]); 
	cout << "\n The array is : "; 
	show(a, asize); 

	cout << "\n\nLet's say we want to search for 2 in the array"; 
	cout << "\n So, we first sort the array"; 
	sort(a, a + asize); 
	cout << "\n\n The array after sorting is : "; 
	show(a, asize); 
	cout << "\n\nNow, we do the binary search"; 
	if (binary_search(a, a + 10, 2)) 
		cout << "\nElement found in the array"; 
	else
		cout << "\nElement not found in the array"; 

	cout << "\n\nNow, say we want to search for 10"; 
	if (binary_search(a, a + 10, 10)) 
		cout << "\nElement found in the array"; 
	else
		cout << "\nElement not found in the array"; 

	return 0; 
} 




The output of the above program is :


The array is : 1 5 8 9 0 6 7 3 4 2 0

Let's say we want to search for 2 in the array
 So, we first sort the array

The array after sorting is : 0 1 2 3 4 5 6 7 8 9

Now, we do the binary search
Element found in the array

Now, say we want to search for 10
Element not found in the array