STL vector基本用法示例

最新推荐文章于 2021-07-06 15:37:56 发布

原创最新推荐文章于 2021-07-06 15:37:56 发布 · 247 阅读

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本文深入探讨了C++标准库中的向量容器使用方法，包括容量、元素操作等核心功能，并通过具体示例展示了向量的各种操作及其效果。

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/// Compile script: 
/// $ g++ -std=c++11 test_vector.cc

#include <vector>
#include <iostream>
#include <string>
using std::vector;
using std::cout;
using std::endl;
using std::string;

template <typename Container>
void print_container(Container c);

int main()
{
  vector<int> v1;
  cout << "v1 capacity: " << v1.capacity() << endl;
  cout << "v1 size: " << v1.size() << endl;
  v1.assign(7, 10);
  cout << "v1 capacity: " << v1.capacity() << endl;
  cout << "v1 size: " << v1.size() << endl;
  print_container<vector<int>>(v1);

  vector<int> v2(v1);
  if (!v2.empty())
    print_container<vector<int>>(v2);

  v1.clear();
  cout << "v1 capacity: " << v1.capacity() << endl;
  cout << "v1 size: " << v1.size() << endl;

  vector<int> v3(7, 10);  // seven 10's
  vector<int> v4(7);  // seven 0's
  cout << "v4 capacity: " << v4.capacity() << endl;
  cout << "v4 size: " << v4.size() << endl;

  vector<int> v5(v4.begin(), v4.end());
  print_container<vector<int>>(v5);

  v5.assign(v3.begin(), v3.end());
  print_container<vector<int>>(v5);  

//  cout << v5.at(7) << endl;  // throw exception
  cout << v5.at(6) << endl;

  cout << v5.back() << endl;

  vector<int>::iterator it = v1.begin();
  cout << *it << endl;

  cout << "v5 before erasing begin: ";
  print_container<vector<int>>(v5);
  vector<int>::iterator bit = v5.begin();
  v5.erase(bit);
  cout << "v5 after erasing begin: ";
  print_container<vector<int>>(v5);

  cout << "v5 capacity: " << v5.capacity() << ", v5 size: " << v5.size() << " before erasing all" << endl;
  v5.erase(v5.begin(), v5.end());
  cout << "v5 capacity: " << v5.capacity() << ", v5 size: " << v5.size() << " after erasing all" << endl;

  vector<int> v6(5, 1);
  vector<int> v7(3, 7);
  v6.insert(v6.begin(), 100);
  cout << "v6 insert at begin: ";
  print_container<vector<int>>(v6);

  v6.insert(v6.begin(), 4, 200);
  cout << "v6 insert 4 items at begin: ";
  print_container<vector<int>>(v6);

  v6.insert(v6.end(), v7.begin(), v7.end());
  cout << "v6 insert v7 at the end: ";
  print_container<vector<int>>(v6);

  cout << "max size of vector<int>: " << v7.max_size() << endl;
  vector<string> vstr;
  cout << "max size of vector<string>: " << vstr.max_size() << endl;

  vector<int> v8(4,5);
  vector<int> v9(5,3);
  v8.swap(v9);
  print_container<vector<int>>(v8);
  print_container<vector<int>>(v9);

  return 0;
}

template <typename Container>
void print_container(Container c)
{
  for (typename Container::iterator it = c.begin();
       it != c.end(); ++it)
  {
    cout << *it << " ";
  }
  cout << endl;
}