Can find_if be used to find a key in std::map/std::unordered_map?

This is a simple program consisting of adding an element into the std::unordered_map. But before it’s added, first check if the key already exists, if it does then don’t add it.

My problem is that since find_if requires only one parameter to be passed in the lambda function, I’m having trouble implementing this since an element on the std::unordered_map is a pair of two types. I wonder if it’s even possible to use find_if and if not what’s the best way to accomplish this?

#include <iostream>
#include <unordered_map>

std::unordered_map <std::string_view, int> myDictionary{};

void addEmployee(std::string_view newName, int newTime)
{
    // first check if they name already exists, if it does then do nothing and return
    auto it{std::find_if(myDictionary.begin(), myDictionary.end(),
                         [&newName]( ??? )
    {
        return newName == myDictionary.first;
    })};

    if (it != myDictionary.end() )
    {
        std::cout << "Name already exists! Wasn't added.\n";
        return;
    }

    // add employee into the map
    myDictionary.insert(std::pair<std::string_view,int> (newName, newTime) );

}

void printDict( std::unordered_map<std::string_view, int>& myDict)
{
    for (auto const& a: myDict)
        std::cout << a.first << " " << a.second << "\n";
}
int main()
{

    addEmployee("Daniel", 14);
    addEmployee("Marco", 433);
    addEmployee("Daniel", 500);     //Should not add it, since key already exists
    addEmployee("Alan", 125);

    printDict(myDictionary);

    return 0;
}

My research so far, and opens questions that I’m still trying to figure out:

• Since std::unordered_map only add uniques keys, it will not add it anyways if I directly insert it, so no need for a check before it (?)
• Going through the documentation for std::unordered_map, I only found find as member function, not find_if, so I’m assuming this is why it cannot be used. If not, then is find the best way to implement this program or using some other alternative like [] work better. (?)

Thanks a lot

>Solution :

Since the name is the key in your unordered_map, you can simply use the unordered_map::find method to check whether it exists:

void addEmployee(std::string_view newName, int newTime)
{
    // first check if they name already exists, if it does then do nothing and return
    auto it = myDictionary.find(newName);
    if (it != myDictionary.end())
    {
        std::cout << "Name already exists! Wasn't added.\n";
        return;
    }
    // add employee into the map
    myDictionary.insert(std::pair<std::string_view, int>(newName, newTime));
}

Live demo