C++ vector向量类模板的使用及解析

#include<iostream>
#include<vector>
#include<stdarg.h>
using namespace std;
using std::cout;
using std::endl;
using std::vector;
int mai(int argc, char* argv[])
{
  vector<int>v1, v2;
  v1.reserve(10);
  v2.reserve(10);
  v1 = vector<int>(8, 7);
  int array[8] = { 1,1,54,24,131,42,42,1331 };
  v2 = vector<int>(array, array + 8);
  cout << "v1容量" << v1.capacity() << endl;
  cout << "v2容量" << v2.capacity() << endl;
  for (decltype(v2.size())i = 0; i < v1.size(); i++) {
    cout << " " << v1[i];
  }
  cout << endl;
  cout << "v2容量" << v2.capacity() << endl;
  cout << "v2当前各项" << endl;
  for (vector<int>::size_type i = 0; i < v1.size(); i++) {
    cout << " " << v2[i] << endl;
  }
  cout << endl;
  v1.resize(0);
  cout << "v1的容量通过resize函数变成0" << endl;
  if (!v1.empty())
    cout << "v1容量" << v1.capacity() << endl;
  else
    cout << "v1是空的" << endl;
  cout << "将v1容量扩展为8" << endl;
  v1.resize(8);
  cout << "v1当前各项" << endl;
  for (decltype(v1.size())i = 0; i < v1.size(); i++)
  {
    cout << "" << v1[i] << endl;
  }
  cout << endl;
  v1.swap(v2);
  cout << "v1与v2交换了" << endl;
  cout << "v1当前各项" << endl;
  cout << "v1容量" << v1.capacity() << endl;
  for (decltype(v1.size())i = 0; i < v1.size(); i++) {
    cout << " " << v1[i] << endl;
  }
  cout << endl;
  v1.push_back(3);
  cout << "v1从后边加入了元素3" << endl;
  cout << "v1容量" << v1.capacity() << endl;
  for (decltype(v1.size())i = 0; i < v1.size(); i++)
  {
    cout << " " << v1[i] << endl;
  }
  cout << endl;
  v1.erase(v1.end() - 2);
  cout << "删除了倒数第二个元素" << endl;
  cout << "v1容量" << v1.capacity() << endl;
  cout << "v1当前各项" << endl;
  for (vector<int>::size_type i = 0; i < v1.size(); i++) {
    cout << " " << v1[i] << endl;
  }
  cout << endl;
  v1.pop_back();
  cout << "v1通过栈操作放走了最后的元素" << endl;
  cout << "v1当前各项" << endl;
  cout << "v1容量" << v1.capacity() << endl;
  for (vector<int>::size_type i = 0; i < v1.size(); i++) {
    cout << " " << v1[i] << endl;
  }
  cout << endl;
  return 0;
}