Standard Template Library Programmer's Guide

The Function Object overview, Adaptable Binary Function, binary_function , plus , minus , multiplies , divides , negate

Category: functors

Component type: type

Negate is a function object. Specifically, it is an Adaptable Unary Function. If f is an object of class negate and x is an object of class T , then f(x) returns -x.

Each element in V2 will be the negative (additive inverse) of the corresponding element in V1 .

const int N = 1000;

vector V1(N);

vector V2(N);

iota(V1.begin(), V1.end(), 1);

assert(V2.size() >= V1.size());

transform(V1.begin(), V1.end(), V2.begin(), negate());

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

Adaptable Unary Function, Default Constructible

T must be a numeric type; if x is an object of type T , then -x must be defined and must have a return type that is convertible to T . T must be Assignable.

unary_function

All of negate 's members are defined in the Adaptable Unary Function and Default Constructible requirements. Negate does not introduce any new members.

The Function Object overview, Adaptable Unary Function, unary_function , plus , minus , multiplies , divides , modulus

Category: functors

Component type: type

Equal_to 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 and x and y are objects of class T , then f(x,y) returns true if x == y and false otherwise.

Rearrange a vector such that all of the elements that are equal to zero precede all nonzero elements.

vector V;

…

partition(V.begin(), V.end(), bind2nd(equal_to(), 0));

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

Adaptable Binary Predicate, DefaultConstructible

T is EqualityComparable.

binary_function.

All of equal_to 's members are defined in the Adaptable Binary Predicate and DefaultConstructible requirements. Equal_to does not introduce any new members.

The function object overview, Adaptable Binary Predicate, not_equal_to , greater , less , greater_equal , less_equal

Category: functors

Component type: type

Not_equal_to 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 not_equal_to and x and y are objects of class T , then f(x,y) returns true if x != y and false otherwise.

Finds the first nonzero element in a list.

list L;

…

list::iterator first_nonzero = find_if(L.begin(), L.end(), bind2nd(not_equal_to(), 0));

assert(first_nonzero == L.end() || *first_nonzero != 0);

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

Adaptable Binary Predicate, DefaultConstructible

T is EqualityComparable.

binary_function.

All of not_equal_to 's members are defined in the Adaptable Binary Predicate and DefaultConstructible requirements. Not_equal_to does not introduce any new members.