C++ Program to Implement LexicoGraphical_Compare in STL

The C++ function std::algorithm::lexicographical_compare() tests whether one range is lexicographically less than another or not. A lexicographical comparison is the kind of comparison generally used to sort words alphabetically in dictionaries.

Declaration

template <class InputIterator1, class InputIterator2>

bool lexicographical_compare(InputIterator1 first1, InputIterator1 last1, InputIterator2 first2, InputIterator2 last2);

Algorithm

Begin
   result = lexicographical_compare(v1.begin(), v1.end(), v2.begin(), v2.end())
   if (result == true)
      Print v1 is less than v2
   result = lexicographical_compare(v1.begin(), v1.end(), v2.begin(), v2.end())
   if (result == false)
      Print v1 is not less than v2
End

Example

 Live Demo

#include <iostream>
#include <vector>
#include <algorithm>
#include <string>
using namespace std;
int main(void) {
   //initialization of v1 and v2
   vector<string> v1 = {"One", "Two", "Three"};
   vector<string> v2 = {"one", "two", "three"};
   bool result;
   result = lexicographical_compare(v1.begin(), v1.end(), v2.begin(), v2.end());
   if (result == true)
      cout << "v1 is less than v2." << endl;
      v1[0] = "two";
      result = lexicographical_compare(v1.begin(), v1.end(), v2.begin(), v2.end());
   if (result == false)
      cout << "v1 is not less than v2." << endl;
   return 0;
}

Output

v1 is less than v2.
v1 is not less than v2.