GeezerVison

The World Wide Web, restored to 800 pixels of glory.

GeezerVison is showing cplusplus.com — std::binary_function

Reference

C library:
- <cassert> (assert.h)
- <cctype> (ctype.h)
- <cerrno> (errno.h)
- C++11
  <cfenv> (fenv.h)
- <cfloat> (float.h)
- C++11
  <cinttypes> (inttypes.h)
- <ciso646> (iso646.h)
- <climits> (limits.h)
- <clocale> (locale.h)
- <cmath> (math.h)
- <csetjmp> (setjmp.h)
- <csignal> (signal.h)
- <cstdarg> (stdarg.h)
- C++11
  <cstdbool> (stdbool.h)
- <cstddef> (stddef.h)
- C++11
  <cstdint> (stdint.h)
- <cstdio> (stdio.h)
- <cstdlib> (stdlib.h)
- <cstring> (string.h)
- C++11
  <ctgmath> (tgmath.h)
- <ctime> (time.h)
- C++11
  <cuchar> (uchar.h)
- <cwchar> (wchar.h)
- <cwctype> (wctype.h)
Containers:
- C++11
  <array>
- <deque>
- C++11
  <forward_list>
- <list>
- <map>
- <queue>
- <set>
- <stack>
- C++11
  <unordered_map>
- C++11
  <unordered_set>
- <vector>
Input/Output:
- <fstream>
- <iomanip>
- <ios>
- <iosfwd>
- <iostream>
- <istream>
- <ostream>
- <sstream>
- <streambuf>
Multi-threading:
- C++11
  <atomic>
- C++11
  <condition_variable>
- C++11
  <future>
- C++11
  <mutex>
- C++11
  <thread>
Other:
- <algorithm>
- <bitset>
- C++11
  <chrono>
- C++11
  <codecvt>
- <complex>
- <exception>
- <functional>
- C++11
  <initializer_list>
- <iterator>
- <limits>
- <locale>
- <memory>
- <new>
- <numeric>
- C++11
  <random>
- C++11
  <ratio>
- C++11
  <regex>
- <stdexcept>
- <string>
- C++11
  <system_error>
- C++11
  <tuple>
- C++11
  <type_traits>
- C++11
  <typeindex>
- <typeinfo>
- <utility>
- <valarray>

<functional>

functions
- C++11
  bind
- C++11
  cref
- C++11
  mem_fn
- not1
- not2
- C++11
  ref
wrapper classes
- binary_negate
- C++11
  function
- C++11
  reference_wrapper
- unary_negate
operator classes
- C++11
  bit_and
- C++11
  bit_or
- C++11
  bit_xor
- divides
- equal_to
- greater
- greater_equal
- less
- less_equal
- logical_and
- logical_not
- logical_or
- minus
- modulus
- multiplies
- negate
- not_equal_to
- plus
other classes
- C++11
  bad_function_call
- C++11
  hash
- C++11
  is_bind_expression
- C++11
  is_placeholder
namespaces
- C++11
  placeholders
deprecated

Reference
<functional>
binary_function

class template

std::binary_function

template <class Arg1, class Arg2, class Result> struct binary_function;

template <class Arg1, class Arg2, class Result> struct binary_function; // deprecated

Binary function object base class

Note: This class has been deprecated in C++11.

This is a base class for standard binary function objects.

Generically, function objects are instances of a class with member function operator() defined. This member function allows the object to be used with the same syntax as a regular function call, and therefore its type can be used as template parameter when a generic function type is expected.

In the case of binary function objects, this operator() member function takes two parameters.

binary_function is just a base class, from which specific binary function objects are derived. It has no operator() member defined (which derived classes are expected to define) - it simply has three public data members that are typedefs of the template parameters. It is defined as:

template <class Arg1, class Arg2, class Result>
  struct binary_function {
    typedef Arg1 first_argument_type;
    typedef Arg2 second_argument_type;
    typedef Result result_type;
  };

Members

member type	definition	notes
`first_argument_type`	The first template parameter (`Arg1`)	Type of the first argument in member `operator()`
`second_argument_type`	The second template parameter (`Arg2`)	Type of the second argument in member `operator()`
`return_type`	The third template parameter (`Result`)	Type returned by member `operator()`

Example

// binary_function example
#include <iostream>     // std::cout, std::cin
#include <functional>   // std::binary_function

struct Compare : public std::binary_function<int,int,bool> {
  bool operator() (int a, int b) {return (a==b);}
};

int main () {
  Compare Compare_object;
  Compare::first_argument_type input1;
  Compare::second_argument_type input2;
  Compare::result_type result;

  std::cout << "Please enter first number: ";
  std::cin >> input1;
  std::cout << "Please enter second number: ";
  std::cin >> input2;

  result = Compare_object (input1,input2);

  std::cout << "Numbers " << input1 << " and " << input2;
  if (result)
	  std::cout << " are equal.\n";
  else
	  std::cout << " are not equal.\n";

  return 0;
}

Possible output:


Please enter first number: 2
Please enter second number: 33
Numbers 2 and 33 are not equal.

functions

wrapper classes

operator classes

other classes

namespaces

deprecated

std::binary_function

Members

Example

See also