Standard Template Library Programmer's Guide

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

Category: functors

Component type: type

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

Find the first nonnegative element in a list.

list L;

…

list::iterator first_nonnegative = find_if(L.begin(), L.end(), bind2nd(greater_equal(), 0));

assert(first_nonnegative == L.end() || *first_nonnegative >= 0);

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

Adaptable Binary Predicate, DefaultConstructible

T is LessThan Comparable.

binary_function.

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

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

Category: functors

Component type: type

Logical_and 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 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]

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

list L;

…

list::iterator in_range = find_if(L.begin(), L.end(), compose2(logical_and(), bind2nd(greater_equal(), 1), bind2nd(less_equal(), 10)));

assert(in_range == L.end() || (*in_range >= 1 && *in_range <= 10));

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

Adaptable Binary Predicate, DefaultConstructible

T must be convertible to bool .

binary_function

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.

[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.

The function object overview, logical_or , logical_not .

Category: functors

Component type: type

Logical_or 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 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 either x or y is true . [1]

Finds the first instance of either ' ' or '\n' in a string.

char str[MAXLEN];

…

const char* wptr = find_if(str, str + MAXLEN, compose2(logical_or(), bind2nd(equal_to(), ' '), bind2nd(equal_to(), '\n')));

assert(wptr == str + MAXLEN || *wptr == ' ' || *wptr == '\n');

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

Adaptable Binary Predicate, DefaultConstructible

T must be convertible to bool .