# Searching in STL C++

Searching is defined as finding the element in group of elements arranged in the particular order. Searching in STL is done by inbuilt function binary_search(). ## Syntax of binary_search() :

```binary_search(start_address, end_address, element to be find);
```

This algorithm’s primary principle is to divide an array in half repeatedly (divide and conquer) until either the element is located or all the elements have been used up. It operates by comparing the middle item in the array with our target; if they match, it returns true; if they don’t, the left sub-array is searched. The search is carried out in the appropriate sub-array if the middle term is less than the target element.

Array must be sorted to apply binary search in stl

#### Example of Searching in STL :

Run
```#include<iostream>
#include<bits/stdc++.h>
using namespace std;

int main() {
int arr[] = {2,4,3,43,4,35,67,99,85,34};
int n = sizeof(arr)/sizeof(arr);
int a = 43;
sort(arr, arr+n);
if(binary_search(arr, arr+n, a)){
cout<<"Element " << a<<" is present in the array";
}
else{
}
return 0;
}
```

### Output :

```Element 43 is present in the array
```

In the above program, we take the array and used sort function to sort the elements , by using binary_search we check elements a is present in the array or not.

### Example of Searching in STL:

Run
```#include<iostream>
#include<bits/stdc++.h>
using namespace std;

int main() {
int arr[] = {2,4,3,43,4,35,67,99,85,34};
int n = sizeof(arr)/sizeof(arr);
int a = 100;
sort(arr, arr+n);
if(binary_search(arr, arr+n, a)){
cout<<"Element " << a<<" is present in the array";
}
else{
}
return 0;
}
```

### Output :

```Element 100 is not found in the array
```

In the above program, we take the array and used sort function to sort the elements , by using binary_search we check elements a is present in the array or not.

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