CODEWITHSUNDEEP
c++vector
Eben Kadile
Eben Kadile

Reputation: 779

How can you get the size of vector as an int?

I'm used to languages where .Length or whatever it may be returns an int but I'm taking a C++ class so I gotta know how to do this. I asked my professor to explain but she didn't want to because the rest of the class is learning about arrays.

First of all, I don't think I fully understand what it is that .size returns. How do I cast whatever .size is to an int? If it's not efficient to do this, how do I loop over the elements of a vector?

Upvotes: 1

Views: 2052

Answers (2)

Raindrop7
Raindrop7

Reputation: 3911

Class std::vector has a member function size() which returns the number of elements pushed in. So use it to get the size as an integer value:

std::vector<int> vecInt;
vecInt.push_back(1);
vecInt.push_back(2);
vecInt.push_back(3);
vecInt.push_back(4);
vecInt.push_back(5);

std::cout << vecInt.size(); // 5

Upvotes: 0

Fran&#231;ois Andrieux
Fran&#231;ois Andrieux

Reputation: 29013

std::vector::size is a member function. You have to call it and it returns the size of the vector. You want to use .size() not .size. Using .size refers to the function (for example if you want to take it's address) where as .size() calls the function.

There are several ways of looping over a vector. The most generic method is the range-based for loop. It works with all standard containers, any user-defined container that provides a proper begin and end method, as well as arrays. For example :

for(const auto & element: my_vect) {
    proc(element);
}

Will call the function proc with every element in the vector my_vect.

Upvotes: 3

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