binary_function Structure Sample
Illustrates how to use the binary_function structure in the Standard Template Library (STL) in Visual C++.
template<class _A1, class _A2, class _R>
struct binary_function
{
typedef _A1 first_argument_type;
typedef _A2 second_argument_type;
typedef _R result_type;
};
Remarks
Observação
The class/parameter names in the prototype do not match the version in the header file. Some have been modified to improve readability.
The binary_function<A,B,C> class is used as a base class to allow the user to easily define binary operator functions that take data types A and B as arguments and return data type C objects.
Example
// binfunc.cpp
// compile with: /EHsc
//
// Structure used: binary_function<A,B,C> - base
// class used to create operator
// functions taking data types A
// and B and returning data type C.
#include <functional>
#include <iostream>
using namespace std ;
class binary_test : public binary_function<binary_test &,int,float>
{
public:
float value;
binary_test(){value=10.0;}
binary_test(float x){value=x;}
result_type operator<<(second_argument_type arg2);
};
binary_test::result_type
binary_test::operator<<(binary_test::second_argument_type arg2)
{
value = (float)(((int)value) << arg2);
cout << "New value after shift is " << value << endl;
return value;
}
int main(void)
{
binary_test item;
cout << "Begin" << endl;
item = item << 2;
}
Output
Begin
New value after shift is 40
Requirements
Header: < functional >