Can problems occur when inserting a hundred elements…

Yes, problems can arise:

Reallocation: When adding elements with push_back, it may exhaust the current allocated memory. In this case, std::vector (the most common container using push_back) is forced to allocate a new, larger block of memory, copy all existing elements there, and free the old block. This can be inefficient in terms of time, especially if reallocations happen frequently.
Invalidation of iterators and references: After reallocation, all iterators, references, and pointers to vector elements obtained before become invalid because the elements have moved to a new memory area. Accessing them through invalid pointers will lead to undefined behavior.
Exceptions: Reallocation may throw a std::bad_alloc exception if it fails to allocate enough memory.
Unpredictable execution time: Due to potential reallocations, the time to insert a single element with push_back can vary: from O(1) (amortized) to O(n) (worst case, during reallocation, where n is the current size of the vector). This can be problematic in real-time systems.

To mitigate these problems, you can use:

reserve(): Pre-allocate memory for a certain number of elements to avoid reallocations when adding the first N elements.

#include <vector>

int main() {
    std::vector<int> my_vector;
    my_vector.reserve(100); // Allocate memory for 100 elements
    for (int i = 0; i < 100; ++i) {
        my_vector.push_back(i); // Insertion without reallocation in this loop
    }
    return 0;
}

emplace_back(): In C++11 and later, prefer emplace_back for types that require expensive copying/moving, as it constructs the object in-place in the vector's memory.

#include <vector>
#include <string>

int main() {
    std::vector<std::string> my_vector;
    my_vector.reserve(100);
    for (int i = 0; i < 100; ++i) {
        my_vector.emplace_back("element" + std::to_string(i)); // Directly constructing the string
    }
    return 0;
}

Can problems occur when inserting a hundred elements using the push_back method?