A vector may allocate more memory than it currently needs.
#include <iostream> #include <vector> using namespace std; int main() { vector<char> vectorObject(10); cout << "Initial size: " << vectorObject.size() << endl; cout << "Initial capacity: " << vectorObject.capacity(); cout << "\n\n"; vectorObject.push_back('X'); cout << "Size after push_back: " << vectorObject.size() << endl; cout << "New capacity: " << vectorObject.capacity(); cout << "\n\n"; vectorObject.resize(100); cout << "Size after resize: " << vectorObject.size() << endl; cout << "Capacity after resize: " << vectorObject.capacity(); cout << "\n\n"; vectorObject.push_back('Y'); cout << "Size after push_back: " << vectorObject.size() << endl; cout << "New capacity: " << vectorObject.capacity(); cout << "\n\n"; return 0; }