Useful Functions
C++ offers several tools to make the iteration process simpler yet safer.
The global functions std::begin, std::end, std::prev, std::next, std::distance and std::advance make your handling of the iterators a lot easier. Only the function std::prev requires a bidirectional iterator. All functions need the header <iterator>. The table gives you an overview:
| Global function | Description |
|---|---|
std::begin(cont) |
Returns a begin iterator to the container cont. |
std::end(cont) |
Returns an end iterator to the container cont. |
std::rbegin(cont) |
Returns a reverse begin iterator to the container cont. |
std::rend(cont) |
Returns a reverse end iterator to the container cont. |
std::cbegin(cont) |
Returns a constant begin iterator to the container cont. |
std::cend(cont) |
Returns a constant end iterator to the container cont. |
std::crbegin(cont) |
Returns a reverse constant begin iterator to the container cont. |
std::crend(cont) |
Returns a reverse constant end iterator to the container cont. |
std::prev(it) |
Returns an iterator, which points to a position before it |
std::next(it) |
Returns an iterator, which points to a position after it. |
std::distance(fir, sec) |
Returns the number of elements between fir and sec. |
std::advance(it, n) |
Puts the iterator it n positions further. |
Useful functions for iterators
Now, the application of the useful functions.