|
|
|
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Old binders and adaptors | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|
|
Defined in header <functional> | ||
template< class Arg1, | (deprecated in C++11) (removed in C++17) | |
std::binary_function
is a base class for creating function objects with two arguments.
std::binary_function
does not defineoperator(); it is expected that derived classes will define this.std::binary_function
provides only three types -first_argument_type
,second_argument_type
andresult_type
- defined by the template parameters.
Some standard library function object adaptors, such asstd::not2, require the function objects they adapt to have certain types defined;std::not2 requires the function object being adapted to have two types namedfirst_argument_type
andsecond_argument_type
. Deriving function objects that take two arguments fromstd::binary_function
is an easy way to make them compatible with those adaptors.
std::binary_function
is deprecated in C++11 and removed in C++17.
Type | Definition |
first_argument_type | Arg1 |
second_argument_type | Arg2 |
result_type | Result |
#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<char> v1{'A','B','C','D','E'};std::vector<char> v2{'E','D','C','B','A'};std::vector<bool> v3(v1.size()); std::transform(v1.begin(), v1.end(), v2.begin(), v3.begin(),std::not2(same())); std::cout<<std::boolalpha;for(std::size_t i=0; i< v1.size();++i)std::cout<< v1[i]<<" != "<< v2[i]<<" : "<< v3[i]<<'\n';}
Output:
A != E : trueB != D : trueC != C : falseD != B : trueE != A : true
(C++11) | copyable wrapper of any copy constructible callable object (class template)[edit] |
(C++23) | move-only wrapper of any callable object that supports qualifiers in a given call signature (class template)[edit] |
(deprecated in C++11)(removed in C++17) | creates an adaptor-compatible function object wrapper from a pointer to function (function template)[edit] |
(deprecated in C++11)(removed in C++17) | adaptor-compatible wrapper for a pointer to binary function (class template)[edit] |
(deprecated in C++11)(removed in C++17) | adaptor-compatible unary function base class (class template)[edit] |