STL入门学习中碰到的一些函数

2020.02.10

• fill

  #include<algorithm>
  vector<int> v{ 1, 2, 3, 3 };
  fill(v.begin(), v.end(), 4);//正向迭代器
  cout << v.size() << endl;
  for (auto x : v)    cout << x << " ";
  

• fill_n

  #include<algorithm>
  vector<int> v{ 1, 2, 3, 3 };
      fill_n(v.begin(), 2, 999);//正向迭代器， 修改个数， 修改值
      cout << v.size() << endl;
      for (auto x : v)    cout << x << " ";
  

• inserter

  #include<iterator>
  vector<int> v{ 1, 2, 3, 3 };
  fill_n(v.begin(), 2, 999);//覆盖 999 999 3 3
  fill_n(inserter(v, v.begin()), 2, 999);//插入 999 999 999 999 3 3
  cout << v.size() << endl;
  for (auto x : v)    cout << x << " ";
  

• set_union

  #include<iterator>
  #define ALL(x) x.begin(), x.end()
  #define INS(x) inserter(x, x.begin())
  set_union(ALL(x1), ALL(x2), INS(x));//集合的并集运算
  set_intersection(ALL(x1), ALL(x2), INS(x));//集合的交集运算
  

• assert

  #include<cassert>
  assert(表达式)//表达式为真时无变化，为假时强行终止程序并给错误提示