lexicographical_compare(3C++) - lexicographical_compare(3C++)
Standard C++ Library Copyright 1998, Rogue Wave Software, Inc.
NAMElexicographical_compare
- Compares two ranges lexicographically.
SYNOPSIS
#include <algorithm>
template <class InputIterator1, class InputIterator2>
bool
lexicographical_compare(InputIterator1 first,
InputIterator2 last1,
InputIterator2 first2,
InputIterator last2);
template <class InputIterator1, class InputIterator2,
class Compare>
bool
lexicographical_compare(InputIterator1 first,
InputIterator2 last1,
InputIterator2 first2,
InputIterator last2, Compare comp);
DESCRIPTION
The lexicographical_compare functions compare each element in the range
[first1, last1) to the corresponding element in the range [first2,
last2) using iterators i and j.
The first version of the algorithm uses operator< as the default com‐
parison operator. It immediately returns true if it encounters any pair
in which *i is less than *j, and immediately returns false if *j is
less than *i. If the algorithm reaches the end of the first sequence
before reaching the end of the second sequence, it also returns true.
The second version of the function takes an argument comp that defines
a comparison function that is used in place of the default operator<.
The lexicographical_compare functions can be used with all the
datatypes included in the standard library.
COMPLEXITYlexicographical_compare performs at most min((last1 - first1), (last2
- first2)) applications of the comparison function.
EXAMPLE
//
// lex_comp.cpp
//
#include <algorithm>
#include <vector>
#include <functional>
#include <iostream>
using namespace std;
int main(void)
{
int d1[5] = {1,3,5,32,64};
int d2[5] = {1,3,2,43,56};
// set up vector
vector<int> v1(d1,d1 + 5), v2(d2,d2 + 5);
// Is v1 less than v2 (I think not)
bool b1 = lexicographical_compare(v1.begin(),
v1.end(), v2.begin(), v2.end());
// Is v2 less than v1 (yup, sure is)
bool b2 = lexicographical_compare(v2.begin(),
v2.end(), v1.begin(), v1.end(), less<int>());
cout << (b1 ? "TRUE" : "FALSE") << " "
<< (b2 ? "TRUE" : "FALSE") << endl;
return 0;
}
Program OutputFALSE TRUEWARNINGS
If your compiler does not support default template parameters, then you
always need to supply the Allocator template argument. For instance,
you have to write:
vector<int, allocator<int> >
instead of:
vector<int>
If your compiler does not support namespaces, then you do not need the
using declaration for std.
Rogue Wave Software 02 Apr 1998 lexicographical_compare(3C++)