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Standard Template Library Programmer's Guide
(document number: 007-3426-004 / published: 1999-05-21) table of contents | additional info | download
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logical_and<T>


Category: functors	Component type: type

Description

Logical_and<T> is a function object; specifically, it is an Adaptable Binary Predicate, which means it is a function object that tests the truth or falsehood of some condition. If f is an object of class logical_and<T> and x and y are objects of class T (where T is convertible to bool) then f(x,y) returns true if and only if both x and y are true. [1]

Example

Finds the first element in a list that lies in the range from 1 to 10.

list<int> L;
...
list<int>::iterator in_range = 
     find_if(L.begin(), L.end(),
             compose2(logical_and<bool>(),
                      bind2nd(greater_equal<int>(), 1),
                      bind2nd(less_equal<int>(), 10)));
assert(in_range == L.end() || (*in_range >= 1 && *in_range <= 10));

Definition

Defined in the standard header functional, and in the nonstandard backward-compatibility header function.h.

Template parameters

Parameter	Description	Default
`T`	The type of `logical_and`'s arguments

Model of

Adaptable Binary Predicate, DefaultConstructible

Type requirements

T must be convertible to bool.

Public base classes

binary_function<T, T, bool>

Members

Member	Where defined	Description
`first_argument_type`	Adaptable Binary Function	The type of the first argument: `T`
`second_argument_type`	Adaptable Binary Function	The type of the second argument: `T`
`result_type`	Adaptable Binary Function	The type of the result: `bool`
`bool operator()(const T& x, const T& y) const`	Binary Function	Function call operator. The return value is `x && y`.
`logical_and()`	Default Constructible	The default constructor.

New members

All of logical_and's members are defined in the Adaptable Binary Function and Default Constructible requirements. Logical_and does not introduce any new members.

Notes

[1] Logical_and and logical_or are not very useful by themselves. They are mainly useful because, when combined with the function object adaptor binary_compose, they perform logical operations on other function objects.