Standard Template Library Programmer's Guide

[2] This restriction is the only reason for priority_queue to exist at all. If iteration through elements is important, you can either use a vector that is maintained in sorted order, or a set , or a vector that is maintained as a heap using make_heap , push_heap , and pop_heap . Priority_queue is, in fact, implemented as a random access container that is maintained as a heap. The only reason to use the container adaptor priority_queue , instead of performing the heap operations manually, is to make it clear that you are never performing any operations that might violate the heap invariant.

[3] One might wonder why pop() returns void , instead of value_type . That is, why must one use top() and pop() to examine and remove the element at the top of the priority_queue , instead of combining the two in a single member function? In fact, there is a good reason for this design. If pop() returned the top element, it would have to return by value rather than by reference: return by reference would create a dangling pointer. Return by value, however, is inefficient: it involves at least one redundant copy constructor call. Since it is impossible for pop() to return a value in such a way as to be both efficient and correct, it is more sensible for it to return no value at all and to require clients to use top() to inspect the value at the top of the priority_queue .

stack , queue , set , make_heap , push_heap , pop_heap , is_heap , sort , is_sorted, Container, Sorted Associative Container, Sequence

Category: containers

Component type: type

Bitset is very similar to vector (also known as bit_vector): it contains a collection of bits, and provides constant-time access to each bit. There are two main differences between bitset and vector . First, the size of a bitset cannot be changed: bitset 's template parameter N , which specifies the number of bits in the bitset, must be an integer constant. Second, bitset is not a Sequence; in fact, it is not an STL Container at all. It does not have iterators, for example, or begin() and end() member functions. Instead, bitset 's interface resembles that of unsigned integers. It defines bitwise arithmetic operators such as &= , |= , and ^= .

In general, bit 0 is the least significant bit and bit N-1 is the most significant bit.

int main() {

const bitset<12> mask(2730ul);

cout << "mask = " << mask << endl;

bitset<12> x;

cout << "Enter a 12-bit bitset in binary: " << flush;

if (cin >> x) {

cout << "x = " << x << endl;

cout << "As ulong: " << x.to_ulong() << endl;

cout << "And with mask: " << (x & mask) << endl;

cout << "Or with mask: " << (x | mask) << endl;

}

}

Defined in the standard header bitset.

Assignable, Default Constructible, Equality Comparable

N is a constant integer expression of a type convertible to size_t , and N is a positive number.

None.

These members are not defined in the Assignable, Default Constructible, or Equality Comparable requirements, but are specific to bitset .