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

c++, vector

Solution

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;

Problem

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?

Original source

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