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Category: functors | | Component type: type |
Description
Select2nd
is a functors that takes a single argument, a pair
[1], and returns the pair's second element.
Example
Print all of a Map
's values.
int main()
{
Map<int, double> M;
M[1] = 0.3;
M[47] = 0.8;
M[33] = 0.1;
transform(M.begin(), M.end(), ostream_iterator<double>(cout, " "),
select2nd<Map<int, double>::value_type>());
}
Definition
Defined in the standard header functional, and in the nonstandard backward-compatibility header function.h. This function object is an SGI extension; it is not part of the C++ standard.
Template parameters
Parameter | Description | Default |
Pair | The function object's argument type. | |
Model of
AdaptableUnaryFunction
Type requirements
There exist some types U
and V
such that Pair
provides the same interface as a pair<U,V>
. [1]
Public base classes
unary_function<Pair, Pair::second_type>
Members
New members
All of select2nd
's members are defined in the AdaptableUnaryFunction requirements. Select2nd
does not introduce any new members.
Notes
[1] Pair
is not actually required to be a pair<U,V>
, but merely to support the same interface as pair
. In almost all cases the template parameter will be a pair
, but it is occasionally useful for it to be something else. One example is a struct
that has the members first
, second
, and third
.
See also
identity
, select1st
, project1st
, project2nd