std::lexicographical_compare

fault (1)	template <class InputIterator1, class InputIterator2> bool lexicographical_compare (InputIterator1 first1, InputIterator1 last1, InputIterator2 first2, InputIterator2 last2);
custom (2)	template <class InputIterator1, class InputIterator2, class Compare> bool lexicographical_compare (InputIterator1 first1, InputIterator1 last1, InputIterator2 first2, InputIterator2 last2, Compare comp);

默认比较函数，使用ASCII 进行比较，例如本例中'A'为65， 'a'为97，因此'a'>'A'。

 

自定义的比较函数mycomp中，将所有的字符转换成为小写，所以第一个未匹配的字符是第三个的'p'和'a'。

 

// lexicographical_compare example
#include <iostream>     // std::cout, std::boolalpha
#include <algorithm>    // std::lexicographical_compare
#include <cctype>       // std::tolower

// a case-insensitive comparison function:
bool mycomp (char c1, char c2)
{ return std::tolower(c1)<std::tolower(c2); }

int main () {
  char foo[]="Apple";
  char bar[]="apartment";

  std::cout << std::boolalpha;

  std::cout << "Comparing foo and bar lexicographically (foo<bar):\n";

  std::cout << "Using default comparison (operator<): ";
  std::cout << std::lexicographical_compare(foo,foo+5,bar,bar+9);
  std::cout << '\n';

  std::cout << "Using mycomp as comparison object: ";
  std::cout << std::lexicographical_compare(foo,foo+5,bar,bar+9,mycomp);
  std::cout << '\n';

  return 0;
}