class template
<functional>
std::multiplies
template <class T> struct multiplies;
Multiplication function object class
Binary function object class whose call returns the result of multiplying its two arguments (as returned by operator *).
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 function call.
It is defined with the same behavior as:
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template <class T> struct multiplies : binary_function <T,T,T> {
T operator() (const T& x, const T& y) const {return x*y;}
};
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template <class T> struct multiplies {
T operator() (const T& x, const T& y) const {return x*y;}
typedef T first_argument_type;
typedef T second_argument_type;
typedef T result_type;
};
Objects of this class can be used on standard algorithms such as transform or accumulate .
Template parameters
- T
- Type of the arguments and return type of the functional call.
The type shall support the operation (operator*).
Member types
| member type | definition | notes |
|---|
| first_argument_type | T | Type of the first argument in member operator() |
| second_argument_type | T | Type of the second argument in member operator() |
| result_type | T | Type returned by member operator() |
Member functions
- T operator() (const T& x, const T& y)
- Member function returning the multiplication of its two arguments (
x*y).
Example
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// factorials (multiplies example)
#include <iostream> // std::cout
#include <functional> // std::multiplies
#include <numeric> // std::partial_sum
int main () {
int numbers[9];
int factorials[9];
for (int i=0;i<9;i++) numbers[i]=i+1;
std::partial_sum (numbers, numbers+9, factorials, std::multiplies<int>());
for (int i=0; i<9; i++)
std::cout << numbers[i] << "! is " << factorials[i] << '\n';
return 0;
}
Output:
1! is 1
2! is 2
3! is 6
4! is 24
5! is 120
6! is 720
7! is 5040
8! is 40320
9! is 362880
See also
- plus
- Addition function object class (class template)
- minus
- Subtraction function object class (class template)
- divides
- Division function object class (class template)
- modulus
- Modulus function object class (class template)
- negate
- Negative function object class (class template)
- equal_to
- Function object class for equality comparison (class template)