Demonstrating the STL vector capacity and reserve functions : vector capacity « vector

Demonstrating the STL vector capacity and reserve functions : vector capacity « vector « C++ Tutorial

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C++ Tutorial » vector » vector capacity

16.7.5.Demonstrating the STL vector capacity and reserve functions

#include <iostream>

#include <cassert>

#include <vector>

using namespace std;



int main()

{

  int N = 10000; // size of vectors



  vector<int> vector1, vector2;



  for (int k = 0; k != N; ++k) {

    vector<int>::size_type cap = vector1.capacity();

    vector1.push_back(k);

    if (vector1.capacity() != cap)

      cout << "k: " << k << ", new capacity: " << vector1.capacity() << endl;

  }



  vector2.reserve(N);

  for (int k = 0; k != N; ++k) {

    vector<int>::size_type cap = vector2.capacity();

    vector2.push_back(k);

    if (vector2.capacity() != cap)

      cout << "k: " << k << ", new capacity: " << vector2.capacity() << "\n";

  }



  return 0;

}

k: 0, new capacity: 1
k: 1, new capacity: 2
k: 2, new capacity: 4
k: 4, new capacity: 8
k: 8, new capacity: 16
k: 16, new capacity: 32
k: 32, new capacity: 64
k: 64, new capacity: 128
k: 128, new capacity: 256
k: 256, new capacity: 512
k: 512, new capacity: 1024
k: 1024, new capacity: 2048
k: 2048, new capacity: 4096
k: 4096, new capacity: 8192
k: 8192, new capacity: 16384

16.7.vector capacity
	16.7.1.	make a big vector and then deallocate all its memory
	16.7.2.	make a big vector and then minimize its memory
	16.7.3.	make the vector as large as possible without reallocating
	16.7.4.	Demonstrating the STL vector capacity
	16.7.5.	Demonstrating the STL vector capacity and reserve functions

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