Summary of the usage of vector in c++

1. Usage of begin() and end() functions, front() and back()

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• begin function

Function prototype:
iterator begin();
const_iterator begin();
Function:
Returns an iterator of the start element in the current vector container.

• end function

Function prototype:
iterator end();
const_iterator end();
Function:
Returns an iterator of the last element in the current vector container.

• front function

Function prototype:
reference front();
const_reference front();
Function:
Returns the reference of the starting element in the current vector container.

• back function

Function prototype:
reference back();
const_reference back();
Function:
Returns the reference to the last element in the current vector container.

2. Usage of begin() and end() functions, front() and back()

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(1) Header file #include.

(2) Create a vector object, vector vec;

(3) Insert numbers at the tail: vec.push_back(a);
delete numbers at the tail: vec.pop_back(b);

(4) Use subscripts to access elements,

cout<<vec[0]<<endl;
//记住下标是从0开始的。

(5) Access elements using iterators

vector<int>::iterator it;
    for(it=vec.begin();it!=vec.end();it++)
     cout<<*it<<endl;

(6) Insert elements: vec.insert(vec.begin()+i,a); insert a before the i+1th element;

(7) Delete element: vec.erase(vec.begin()+2); delete the third element

vec.erase(vec.begin()+i,vec.end()+j); delete interval [i,j-1]; interval starts from 0

(8) Vector size: vec.size();

(9) Clear: vec.clear();

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Reference document: That year Cong Cong's blog