How to expand array c++ (add element)?

Question

C++ / C#

In the loop, I get up to 10k values ​​that need to be quickly written to the array, while I don’t know exactly how many there will be, but there should not be empty values. If I define an array with length 1 , then how to expand (complement) it?

Answer 1

Use std::vector. It expands automatically and is fast at the same time.

Answer 2

In the case when you need to expand the array, you can, for example, use the realloc() function.
It will be like this:
Instead of int, you put the data type you are working with. plus_one_element will allocate plus one memory location for the number at each step of the for loop. Then in arr[plus_one_element - 1] you write down the desired value. We do minus one, since the array is initialized from scratch. Read about dynamic arrays and realloc.

for (int plus_one_element = 1; plus_one_element < 10001; plus_one_element++) 
     arr = (int*)realloc(arr, plus_one_element*sizeof(int))
     std::cin << arr[plus_one_element - 1];