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