std::binary_function
| Defined in header <functional>
|
||
| template< class Arg1, |
(deprecated) | |
binary_function is a base class for creating function objects with two arguments.
binary_function does not define operator(); it is expected that derived classes will define this. binary_function provides only three types - first_argument_type, second_argument_type and result_type - defined by the template parameters.
Some standard library function object adaptors, such as std::not2, require the function objects they adapt to have certain types defined; std::not2 requires the function object being adapted to have two types named first_argument_type and second_argument_type. Deriving function objects that take two arguments from binary_function is an easy way to make them compatible with those adaptors.
binary_function is deprecated in C++11. Its functionality has been made obsolete by std::function.
[edit] Member types
| Type | Definition |
| first_argument_type | Arg1 |
| second_argument_type | Arg2 |
| result_type | Result |
[edit] Example
#include <algorithm> #include <functional> #include <iostream> #include <vector> struct same : std::binary_function<int, int, bool> { bool operator()(int a, int b) const { return a == b; } }; int main() { std::vector<int> v1; std::vector<int> v2; for (int i = 0; i < 10; ++i) v1.push_back(i); for (int i = 0; i < v1.size(); ++i) v2.push_back(10 - i); std::vector<bool> v3(v1.size()); std::transform(v1.begin(), v1.end(), v2.begin(), v3.begin(), std::not2(same())); /* C++11 solution: // Cast to std::function<bool (int, int)> somehow - even with a lambda std::transform(v1.begin(), v1.end(), v2.begin(), v3.begin(), std::not2(std::function<bool (int, int)>( [](int a, int b){ return a == b; } )) ); */ std::cout.setf(std::ios_base::boolalpha); for (int i = 0; i < v1.size(); ++i) std::cout << v1[i] << ' ' << v2[i] << ' ' << v3[i] << '\n'; }
Output:
0 10 true 1 9 true 2 8 true 3 7 true 4 6 true 5 5 false 6 4 true 7 3 true 8 2 true 9 1 true
[edit] See also
| (C++11) |
wraps callable object of any type with specified function call signature (class template) |
| (deprecated) |
creates an adaptor-compatible function object wrapper from a pointer to function (function template) |
| (deprecated) |
adaptor-compatible wrapper for a pointer to binary function (class template) |
| (deprecated) |
adaptor-compatible unary function base class (class template) |
