> 
> **Possible Duplicate:**  
> 
> [How to find an item in a std::vector?](https://stackoverflow.com/questions/571394/how-to-find-an-item-in-a-stdvector) 
> 
> 
> 

Given these two classes:

```
class Book
{
private:

  string title;
  int category;

public:

  Book(const string& , int num);
}

Book(const string& name, int num)
  :title(name), category(num)
{ }

class Reader
{
private:

string reader_name;
vector <Book> bookLists;

public:

void add(const Book &ref);
};

void add(const Book& ref)
{
    // My problem is here.
}

```

I want to search inside the vector of Book. If the Book is in the vector of Book, it does nothing. If the Book is not in the vector of Book `bookLists.push_back(ref);`