C++ lexicographical_compare 有什么用？

Question

我想使用 c++ 算法库中的函数 lexicographical_compare。

但就using语句而言，我不知道该写什么。例如

using std::lexicographical_compare ??

我以后该如何解决这个问题？

谢谢

Answer 1

就这样

 using std::lexicographical_compare;

然后(从 SGI STL Doc 复制)

int main()
{
  int A1[] = {3, 1, 4, 1, 5, 9, 3};
  int A2[] = {3, 1, 4, 2, 8, 5, 7};
  int A3[] = {1, 2, 3, 4};
  int A4[] = {1, 2, 3, 4, 5};

  const int N1 = sizeof(A1) / sizeof(int);
  const int N2 = sizeof(A2) / sizeof(int);
  const int N3 = sizeof(A3) / sizeof(int);
  const int N4 = sizeof(A4) / sizeof(int);

  bool C12 = lexicographical_compare(A1, A1 + N1, A2, A2 + N2);
  bool C34 = lexicographical_compare(A3, A3 + N3, A4, A4 + N4);

  cout << "A1[] < A2[]: " << (C12 ? "true" : "false") << endl;
  cout << "A3[] < A4[]: " << (C34 ? "true" : "false") << endl;
}

或者

// no using statement

int main()
{
   //... same as above
   bool C12 = std::lexicographical_compare(A1, A1 + N1, A2, A2 + N2);
   bool C34 = std::lexicographical_compare(A3, A3 + N3, A4, A4 + N4);
   //... same as above
}

要了解 future 的自己，请从头到尾阅读一本 C++ 书籍(例如 Stroustrup 的“The C++ Programming Language”)。