modulus Struct

Article
08/03/2021

A predefined function object that performs the modulus division operation (operator%) on its arguments.

Syntax

template <class Type = void>
struct modulus : public binary_function <Type, Type, Type>
{
    Type operator()(const Type& Left, const Type& Right) const;
};

// specialized transparent functor for operator%
template <>
struct modulus<void>
{
  template <class T, class U>
  auto operator()(T&& Left, U&& Right) const
    -> decltype(std::forward<T>(Left) % std::forward<U>(Right));
};

Parameters

Type, T, U
Any type that supports an operator% that takes operands of the specified or inferred types.

Left
The left operand of the modulus operation. The unspecialized template takes an lvalue reference argument of type Type. The specialized template does perfect forwarding of lvalue and rvalue reference arguments of inferred type T.

Right
The right operand of the modulus operation. The unspecialized template takes an lvalue reference argument of type Type. The specialized template does perfect forwarding of lvalue and rvalue reference arguments of inferred type U.

Return Value

The result of Left % Right. The specialized template does perfect forwarding of the result, which has the type that's returned by operator%.

Remarks

The modulus functor is restricted to integral types for the basic data types, or to user-defined types that implement operator%.

Example

// functional_modulus.cpp
// compile with: /EHsc
#include <vector>
#include <functional>
#include <algorithm>
#include <iostream>

using namespace std;

int main( )
{
   vector <int> v1, v2, v3 ( 6 );
   vector <int>::iterator Iter1, Iter2, Iter3;

   int i;
   for ( i = 1 ; i <= 6 ; i++ )
   {
      v1.push_back( 5 * i );
   }

   int j;
   for ( j = 1 ; j <= 6 ; j++ )
   {
      v2.push_back( 3 * j );
   }

   cout << "The vector v1 = ( " ;
   for ( Iter1 = v1.begin( ) ; Iter1 != v1.end( ) ; Iter1++ )
      cout << *Iter1 << " ";
   cout << ")" << endl;

   cout << "The vector v2 = ( " ;
   for ( Iter2 = v2.begin( ) ; Iter2 != v2.end( ) ; Iter2++ )
      cout << *Iter2 << " ";
   cout << ")" << endl;

   // Finding the element-wise remainders of the elements of v1 & v2
   transform (v1.begin( ),  v1.end( ), v2.begin( ), v3.begin ( ),
      modulus<int>() );

   cout << "The element-wise remainders of the modular division\n are: ( " ;
   for ( Iter3 = v3.begin( ) ; Iter3 != v3.end( ) ; Iter3++ )
      cout << *Iter3 << " ";
   cout << ")" << endl;
}

The vector v1 = ( 5 10 15 20 25 30 )
The vector v2 = ( 3 6 9 12 15 18 )
The element-wise remainders of the modular division
are: ( 2 4 6 8 10 12 )

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