public member function
<vector>
iterator begin();
const_iterator begin() const;
iterator begin() noexcept;
const_iterator begin() const noexcept;
Return iterator to beginning
Returns an iterator pointing to the first element in the vector.
Notice that, unlike member vector::front, which returns a reference to the first element, this function returns a random access iterator pointing to it.
If the container is empty, the returned iterator value shall not be dereferenced.
Return Value
An iterator to the beginning of the sequence container.
If the vector object is const-qualified, the function returns a const_iterator. Otherwise, it returns an iterator.
Member types iterator and const_iterator are random access iterator types (pointing to an element and to a const element, respectively).
Example
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
|
// vector::begin/end
#include <iostream>
#include <vector>
int main ()
{
std::vector<int> myvector;
for (int i=1; i<=5; i++) myvector.push_back(i);
std::cout << "myvector contains:";
for (std::vector<int>::iterator it = myvector.begin() ; it != myvector.end(); ++it)
std::cout << ' ' << *it;
std::cout << '\n';
return 0;
}
| |
Output:
myvector contains: 1 2 3 4 5
|
Iterator validity
No changes.
Data races
The container is accessed (neither the const nor the non-const versions modify the container).
No contained elements are accessed by the call, but the iterator returned can be used to access or modify elements. Concurrently accessing or modifying different elements is safe.
Exception safety
No-throw guarantee: this member function never throws exceptions.
The copy construction or assignment of the returned iterator is also guaranteed to never throw.
See also
- vector::front
- Access first element (public member function
)
- vector::end
- Return iterator to end (public member function
)
- vector::rbegin
- Return reverse iterator to reverse beginning (public member function
)
- vector::rend
- Return reverse iterator to reverse end (public member function
)