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vector :: cbegin() and vector :: cend() in C++ STL

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Vectors are known as dynamic arrays which can change its size automatically when an element is inserted or deleted. This storage is maintained by container.

vector::cbegin()

The function returns an iterator which is used to iterate container.

  • The iterator points to the beginning of the vector.
  • Iterator cannot modify the contents of the vector.

Syntax:

vectorname.cbegin()

Parameters: There is no parameter Return value: Constant random access iterator points to the beginning of the vector. Exception: No exception

Time Complexity – constant O(1)

Below program(s) illustrate the working of the function 

CPP




// CPP program to illustrate
// use of cbegin()
#include <iostream>
#include <string>
#include <vector>
 
using namespace std;
 
int main()
{
    vector<string> vec;
 
    // 5 string are inserted
    vec.push_back("first");
    vec.push_back("second");
    vec.push_back("third");
    vec.push_back("fourth");
    vec.push_back("fifth");
 
    // displaying the contents
    cout << "Contents of the vector:" << endl;
    for (auto itr = vec.cbegin();
         itr != vec.end();
         ++itr)
        cout << *itr << endl;
 
    return 0;
}


Output:

Contents of the vector:
first
second
third
fourth
fifth
vector::cend()

The function returns an iterator which is used to iterate container.

  • The iterator points to past-the-end element of the vector.
  • Iterator cannot modify the contents of the vector.

Syntax:

vectorname.cend()

Parameters: There is no parameter Return value: Constant random access iterator points to past-the-end element of the vector. Exception: No exception

Time Complexity – constant O(1)

Below program(s) illustrate the working of the function 

CPP




// CPP programto illustrate
// functioning of cend()
#include <iostream>
#include <string>
#include <vector>
 
using namespace std;
 
int main()
{
    vector<string> vec;
 
    // 5 string are inserted
    vec.push_back("first");
    vec.push_back("second");
    vec.push_back("third");
    vec.push_back("fourth");
    vec.push_back("fifth");
 
    // displaying the contents
    cout << "Contents of the vector:" << endl;
    for (auto itr = vec.cend() - 1;
         itr >= vec.begin();
         --itr)
        cout << *itr << endl;
 
    return 0;
}


Output:

Contents of the vector:
fifth
fourth
third
second
first


Last Updated : 09 Jun, 2022
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