c++ find element in vector

#include <algorithm>
#include <vector>

if ( std::find(vec.begin(), vec.end(), item) != vec.end() )
   do_this();
else
   do_that();

	std::vector<int>::iterator it; 
 
    it = std::find (vec.begin(), vec.end(), ser); 
    if (it != vec.end()) 
    { 
        std::cout << "Element " << ser <<" found at position : " ; 
        std::cout << it - vec.begin() << " (counting from zero) \n" ; 
    } 
    else
        std::cout << "Element not found.\n\n";          

auto it = find(vec.begin(),vec,end(), item)!
if(it != vec.end()){
 	 int index = it - vec.begin();
}

// CPP program to illustrate  
// std::find 
// CPP program to illustrate  
// std::find 
#include<bits/stdc++.h> 
  
int main () 
{ 
    std::vector<int> vec { 10, 20, 30, 40 }; 
      
    // Iterator used to store the position  
    // of searched element 
    std::vector<int>::iterator it; 
      
    // Print Original Vector 
    std::cout << "Original vector :"; 
    for (int i=0; i<vec.size(); i++) 
        std::cout << " " << vec[i]; 
          
    std::cout << "\n"; 
      
    // Element to be searched 
    int ser = 30; 
      
    // std::find function call 
    it = std::find (vec.begin(), vec.end(), ser); 
    if (it != vec.end()) 
    { 
        std::cout << "Element " << ser <<" found at position : " ; 
        std::cout << it - vec.begin() << " (counting from zero) \n" ; 
    } 
    else
        std::cout << "Element not found.\n\n"; 
          
    return 0; 
}