less

Library:  General utilities

Does not inherit

• Local Index
• Summary
• Synopsis
• Description
• Interface
• See Also
• Standards Conformance

A binary function object that returns true if its first argument is less than its second

#include <functional>

namespace std {
  template <class T>
  struct less;
}

less is a binary function object. Its operator() returns true if x is less than y. You can pass a less object to any algorithm that requires a binary function. For example, the sort() algorithm can accept a binary function as an alternate comparison object to sort a sequence. less would be used in that algorithm in the following manner:

vector<int> vec1;
.
.
sort(vec1.begin(), vec1.end(), less<int>());

After this call to sort(), vec1 is sorted in ascending order.

namespace std {

  template <class T>
  struct less : binary_function<T, T, bool> {
    bool operator() (const T&, const T&) const;
  };
}

binary_function, Function Objects

ISO/IEC 14882:1998 -- International Standard for Information Systems -- Programming Language C++, Section 20.3.3