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c++vectorpush-back

Push_back function for Class defined vector

I have a vector that takes in class values of a class called Bug which stores a mass and number of legs for each instance. I'm having trouble using the push_back function, and suspect it's just a syntax issue, but can't figure out exactly what I'm doing wrong. I am trying to add 3 more values into the end of the vector. Here is my partial code:

std::vector<Bug> bugs(5); //vector definition
bugs.push_back(3);
Solution

  • if you are trying to add 3 default constructed Bugs, you will need to call push_back 3 times: 

    struct Bug{};  
std::vector<Bug> bugs(5); //vector instantiation 
bugs.push_back(Bug{});
bugs.push_back(Bug{});
bugs.push_back(Bug{});

    You can also use emplace_back(). It expects constructor arguments.
    In this case, no arguments: 

    struct Bug{};  
std::vector<Bug> bugs(5);
bugs.emplace_back();
bugs.emplace_back();
bugs.emplace_back();

    Apart from using a loop, you can add N new elements using resize: 

    bugs.resize(bugs.size()+n);