Книга: Standard Template Library Programmer
equal_to
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equal_to<T>
Category: functors
Component type: type
Description
Equal_to<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 equal_to<T> and x and y are objects of class T, then f(x,y) returns true if x == y and false otherwise.
Example
Rearrange a vector such that all of the elements that are equal to zero precede all nonzero elements.
vector<int> V;
…
partition(V.begin(), V.end(), bind2nd(equal_to<int>(), 0));
Definition
Defined in the standard header functional, and in the nonstandard backward-compatibility header function.h.
Template parameters
| Parameter | Description |
|---|---|
T |
The type of equal_to's arguments. |
Model of
Adaptable Binary Predicate, DefaultConstructible
Type requirements
T is EqualityComparable.
Public base classes
binary_function<T, T, bool>.
Members
| Member | Where defined | Description |
|---|---|---|
first_argument_type |
Adaptable Binary Predicate | The type of the first argument: T |
second_argument_type |
Adaptable Binary Predicate | The type of the second argument: T |
result_type |
Adaptable Binary Predicate | The type of the result: bool |
equal_to() |
DefaultConstructible | The default constructor. |
bool operator()(const T& x, const T& y) |
Binary Function | Function call operator. The return value is x == y. |
New members
All of equal_to's members are defined in the Adaptable Binary Predicate and DefaultConstructible requirements. Equal_to does not introduce any new members.
See also
The function object overview, Adaptable Binary Predicate, not_equal_to, greater, less, greater_equal, less_equal
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