How to create a vector of user defined size but with no predefined values? [closed]

Question

In C++ one can create an array of predefined size, such as 20, with int myarray[20]. However, the online documentation on vectors doesn't show an alike way of initialising vectors: Instead, a vector should be initialised with, for example, std::vector<int> myvector (4, 100);. This gives a vector of size 4 with all elements being the value 100.

How can a vector be initialised with only a predefined size and no predefined value, like with arrays?

Answer 1

With the constructor:

// create a vector with 20 integer elements std::vector<int> arr(20);  for(int x = 0; x < 20; ++x)    arr[x] = x;