erase |
C++ Library |
iterator erase(iterator it)
Removes from the vector container, the element positioned at it.
iterator erase(iterator first, iterator last)
Removes from the vector container, the elements in the range [first, last).
Both of the above return an iterator that designates the first element remaining beyond any elements removed, or end() if no such element exists.
The member function invalidates all the iterators and references to the vector container. The number of calls to the destructor (of the erased type T) is the same as the number of elements erased, but the number of calls to the assignment operator of T is equal to the minimum of the number of elements before the erased elements and the number of elements after the erased elements.
#include <vector>
#include <iostream>
int main()
{
//default constructor
std::vector<int> c1 ;
//create vector with 10 copies of 4
std::vector<int> c2(10, 4) ;
//copy constructor
std::vector<int> c3(c2) ;
int ai[] = {0, 1, 2, 3, 4, 5} ;
int i ;
//range copy constructor
std::vector<int> c4(ai, ai+5) ;
std::vector<int> c5 ;
//push_back
for(i = 0; i < 5; i++)
c5.push_back(ai[i]) ;
//get_allocator
std::vector<int>::allocator_type a1 = c4.get_allocator() ;
//begin, end
std::cout << "c4 (using begin, end) = " ;
std::vector<int>::iterator Iter ;
for(Iter = c4.begin(); Iter != c4.end(); Iter++)
std::cout << *Iter << ", " ;
std::cout << std::endl ;
//rbegin, rend
std::cout << "c4 (using rbegin, rend) = " ;
std::vector<int>::reverse_iterator RevIter ;
for(RevIter = c4.rbegin(); RevIter != c4.rend(); RevIter++)
std::cout << *RevIter << ", " ;
std::cout << std::endl ;
//assign
c2.assign(ai, ai+4) ;
c1.assign(10, 4) ;
//at
std::cout << "third element in c1 = " << c1.at(3) << std::endl ;
//operator[]
std::cout << "c4[3] = " << c4[3] << std::endl ;
//back
std::cout << "last element in c2 = " << c2.back() << std::endl ;
//front
std::cout << "first element in c2 = " << c2.front() << std::endl ;
//size
std::cout << "number of elements in c2 = " << c2.size() << std::endl ;
//max_size
std::cout << "max number of elements c2 can hold using current allocator = "
<< c2.max_size() << std::endl ;
//erase
c3.erase(c3.begin(), c3.begin() + 4) ;
//clear
c2.clear() ;
//empty
if (c2.empty() == true)
std::cout << "c2 is now empty" << std::endl ;
//resize
c2.resize(10, 30) ;
std::cout << "number of elements in c2 = " << c2.size() << std::endl ;
std::cout << "last element in c2 = " << c2.back() << std::endl ;
std::cout << "first element in c2 = " << c2.front() << std::endl ;
//reserve, capacity
c2.reserve(70) ;
std::cout << "current capacity of c2 = "
<< c2.capacity() << std::endl ;
//pop_back
c2.pop_back() ;
std::cout << "last element in c2 = " << c2.back() << std::endl ;
//swap
c3.swap(c2) ;
std::cout << "number of elements in c3 = " << c3.size() << std::endl ;
std::cout << "last element in c3 = " << c3.back() << std::endl ;
std::cout << "first element in c3 = " << c3.front() << std::endl ;
//insert
c1.insert(c1.begin(), 20) ;
c1.insert(c1.begin()+1, 4, 10) ;
c1.insert(c1.begin()+2, c5.begin(), c5.end()) ;
std::cout << "c1 = " ;
for(Iter = c1.begin(); Iter != c1.end(); Iter++)
std::cout << *Iter << ", " ;
std::cout << std::endl ;
return 0 ;
}
c4 (using begin, end) = 0, 1, 2, 3, 4, c4 (using rbegin, rend) = 4, 3, 2, 1, 0, third element in c1 = 4 c4[3] = 3 last element in c2 = 3 first element in c2 = 0 number of elements in c2 = 4 max number of elements c2 can hold using current allocator = 1073741823 c2 is now empty number of elements in c2 = 10 last element in c2 = 30 first element in c2 = 30 current capacity of c2 = 70 last element in c2 = 30 number of elements in c3 = 9 last element in c3 = 30 first element in c3 = 30 c1 = 20, 10, 0, 1, 2, 3, 4, 10, 10, 10, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,