Is there a convenient way to initialize std::pair<string, int>::second to 0?-CodePudding

    vector<pair<const string, int>> v{ {"XXX", 0}, {"YYY", 0}, {"ZZZ", 0} };
    for (size_t i = 0; i < v.size(); i  )
    {
        cout << v[i].second << endl;
    }

Do I have to explicitly assign 0 for every element? Is there a convenient way to do this?

PS: To replace 0 with {} won't help.

CodePudding user response：

Not too much good way, I give this solution,

    auto my_make_pair = [](string&& s)->pair<const string, unsigned> {
        return { s,0 };
    };
    vector<pair<const string, int>> v{ my_make_pair("XXX"), my_make_pair("YYY"), my_make_pair("ZZZ") };
    for (size_t i = 0; i < v.size(); i  )
    {
        cout << v[i].second << endl;
    }

CodePudding user response：

When you want elements in a vector to be initialized with default values, just declare your vector using a constructor with one parameter which is the size of your vector:

#include <iostream>
#include <vector>

using namespace std;

int main()
{
    constexpr uint8_t number_of_pairs{3}; // desired size
    vector<pair<const string, int>> v(number_of_pairs);
    for (size_t i = 0; i < v.size(); i  )
    {
        cout << v[i].second << endl;
    }

    return 0;
}