What approach would you use for storing large amounts of data when its initial size is unknown?

To store large amounts of data with initially unknown size in C/C++, dynamic memory allocation and data structures that can expand as needed are usually used.

Main approaches:

• Use dynamic arrays with reallocation (for example, using realloc in C or std::vector in C++), which increase in size when the current capacity is reached.
• For very large data — use file storage or databases to avoid keeping everything in RAM.

Example with std::vector in C++:

#include <vector>

std::vector<int> data;

// Add elements as they come
for (int i = 0; i < n; ++i) {
    int value;
    std::cin >> value;
    data.push_back(value);
}

std::vector automatically manages memory and expands when necessary.