c++,vector,std , Add same value multiple times to std::vector (repeat)


Add same value multiple times to std::vector (repeat)

Question:

Tag: c++,vector,std

I want to add a value multiple times to an std::vector. E.g. add the interger value 1 five times to the vector:

std::vector<int> vec;
vec.add(1, 5);

vec should be of the form {1,1,1,1,1} afterwards. Is there a clean c++ way to do so?


Answer:

It really depends what you want to do.

Make a vector of length 5, filled with ones:

std::vector<int> vec(5, 1);

Grow a vector by 5 and fill it with ones:

std::vector<int> vec;
// ...
vec.insert(vec.end(), 5, 1);

Or resize it (if you know the initial size):

std::vector<int> vec(0);
vec.resize(5, 1);

You can also fill with elements using one of the many versions of fill, for example:

fill_n(back_inserter(vec), 5, 1);

and so on.... Read the library documentation, some of these return useful information, too.


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