Vector series--c++11 to vector member functions (Cbegin (), Cend (), Crbegin (), Crend (), Emplace (), data () in combat C + +

The emplace_back mentioned above is the added content of c++11.

So this blog is to list the c++11 to the vector container expansion.

Std::vector::cbegin and Std::vector::cend
These two methods are corresponding to Std::vector::begin and Std::vector::end, from the literal can be seen, more than a ' C ', as the name implies is the meaning of const.
So:
Std::vector::cbegin: Returns a const_iterator pointing to the first element in the container.
Std::vector::cend: Returns a const_iterator pointing to the past-the-end element in the container.

#include <iostream>#include <vector>intMain () {STD:: vector<int>Myvector = {Ten, -, -, +, -};STD::cout<<"Myvector contains:"; for(Autoit = Myvector.cbegin (); It! = Myvector.cend (); ++it)STD::cout<<"'<< *it;STD::cout<<' \ n ';return 0;} Output:myvector contains:Ten  -  -  +  -

Std::vector::crbegin and Std::vector::crend
These two methods do not explain, compared to the above is more than a ' r ', reverse abbreviation, reverse iterator, the code is omitted.

Std::vector::emplace
Emplace_back has been discussed before, in fact, there is a method called Emplace.
What I want to say is that emplace to Emplace_back is like the insert to push_back.
Reading the English description is intuitive:

Emplace:construct and insert Element
Emplace_back:construct and insert element at the end

How to use:

#include <iostream>#include <vector>intMain () {STD:: vector<int>Myvector = {Ten, -, -};Autoit = Myvector.emplace (Myvector.begin () +1, -); Myvector.emplace (IT, $); Myvector.emplace (Myvector.end (), -);STD::cout<<"Myvector contains:"; for(Auto& X:myvector)STD::cout<<"'<< x;STD::cout<<' \ n ';return 0;} Output:myvector contains:Ten  $  -  -  -  -

std::vector::d ata
Returns a direct pointer to the memory array used internally by the vector to store its owned elements.

#include <iostream>#include <vector>intMain () {STD:: vector<int>Myvector (5);int* p = myvector.data (); *p =Ten;  ++p; *p = -; p[2] = -;STD::cout<<"Myvector contains:"; for(unsignedI=0; I<myvector.size (); ++i)STD::cout<<"'<< Myvector[i];STD::cout<<' \ n ';return 0;} Output:myvector contains:Ten  - 0  - 0

Std::vector::shrink_to_fit
Requests the container to reduce their capacity to fit their size.
is to reduce space

#include <iostream>#include <vector>intMain () {STD:: vector<int>Myvector ( -);STD::cout<<"1. Capacity of Myvector: "<< myvector.capacity () <<' \ n ';STD::cout<<"1. Size of Myvector: "<< myvector.size () <<' \ n '; Myvector.resize (Ten);STD::cout<<"2. Capacity of Myvector: "<< myvector.capacity () <<' \ n ';STD::cout<<"2. Size of Myvector: "<< myvector.size () <<' \ n '; Myvector.shrink_to_fit ();STD::cout<<"3. Capacity of Myvector: "<< myvector.capacity () <<' \ n ';STD::cout<<"3. Size of Myvector: "<< myvector.size () <<' \ n ';return 0;}//Output1.Capacity of Myvector: -1.Size of Myvector: -2.Capacity of Myvector: -2.Size of Myvector:Ten3.Capacity of Myvector:Ten3.Size of Myvector:Ten

At this point, it is to understand the difference between size and capacity, will be more understanding of the difference between resize and reserve!

Vector series--c++11 to vector member functions (Cbegin (), Cend (), Crbegin (), Crend (), Emplace (), data () in combat C + +