C++ Standard Library Functions

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C++ Standard Library Functions

Many C++ standard library functions operate on sequences denoted by iterators or pointers. Iterators are a family of types that include pointers. They are classified by the operators they support.

input: ++p, p++, p=q, p==q, p!=q, *p (read-only)
output: p=q, p==q, p!=q, *p++ = x (alternating write/increment)
forward: input and output and p->m, *p (multiple read-write)
bidirectional: forward and --p, p--, implemented by list, map, multimap, set, multiset.
random: bidirectional and p<q, p>q, p<=q, p>=q, p+i, i+p, p-i, p-q, p, implemented by arrays (as pointers), string, vector, deque.
Some algorithms require certain iterator types, but will accept more powerful types. For example, copy(b, e, d) require b and e to be at least input iterators and d to be at least an output iterator. But it will accept forward, bidirectional, or random iterators because these all support input and output operations. sort() requires random iterators and will accept no other type.

The notation [b,e) denotes the sequence of e-b objects from b[0] to e[-1], i.e. b points to the beginning of the sequence and e points one past the end. For most containers, v, the sequence is [v.begin(), v.end()). For an array of n elements, the sequence is [a, a+n).