greater Struct
The latest version of this topic can be found at greater Struct.
A binary predicate that performs the greater-than operation ( operator>) on its arguments.
Syntax
template <class Type = void>
struct greater : public binary_function <Type, Type, bool>
{
bool operator()(
const Type& Left,
const Type& Right) const;
};
// specialized transparent functor for operator>
template <>
struct greater<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 greater-than 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 greater-than 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 binary predicate greater< Type> provides a strict weak ordering of a set of element values of type Type into equivalence classes, if and only if this type satisfies the standard mathematical requirements for being so ordered. The specializations for any pointer type yield a total ordering of elements, in that all elements of distinct values are ordered with respect to each other.
Example
// functional_greater.cpp
// compile with: /EHsc
#include <vector>
#include <algorithm>
#include <functional>
#include <cstdlib>
#include <iostream>
int main( )
{
using namespace std;
vector <int> v1;
vector <int>::iterator Iter1;
int i;
for ( i = 0 ; i < 8 ; i++ )
{
v1.push_back( rand( ) );
}
cout << "Original vector v1 = ( " ;
for ( Iter1 = v1.begin( ) ; Iter1 != v1.end( ) ; Iter1++ )
cout << *Iter1 << " ";
cout << ")" << endl;
// To sort in ascending order,
// use default binary predicate less<int>( )
sort( v1.begin( ), v1.end( ) );
cout << "Sorted vector v1 = ( " ;
for ( Iter1 = v1.begin( ) ; Iter1 != v1.end( ) ; Iter1++ )
cout << *Iter1 << " ";
cout << ")" << endl;
// To sort in descending order,
// specify binary predicate greater<int>( )
sort( v1.begin( ), v1.end( ), greater<int>( ) );
cout << "Resorted vector v1 = ( " ;
for ( Iter1 = v1.begin( ) ; Iter1 != v1.end( ) ; Iter1++ )
cout << *Iter1 << " ";
cout << ")" << endl;
}
Output
Original vector v1 = (41 18467 6334 26500 19169 15724 11478 29358)
Sorted vector v1 = (41 6334 11478 15724 18467 19169 26500 29358)
Resorted vector v1 = (29358 26500 19169 18467 15724 11478 6334 41)
Requirements
Header: <functional>
Namespace: std