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Last element of vector in C++ (Accessing and updating)
In this article, we will be discussing the ways of accessing and updating the last element of a vector in C++.
What is a vector template?
Vectors are sequence containers whose size is changed dynamically. A container is an object that holds data of the same type. Sequence containers store elements strictly in a linear sequence.
Vector container stores the elements in contiguous memory locations and enables direct access to any element using a subscript operator []. Unlike arrays, the vector’s size is dynamic. The storage of the vector is handled automatically.
Definition of vector
Template <class T, class Alloc = allocator<T>> class vector;
Parameters of vector
The function accepts the following parameter(s) −
T − This is the type of element contained.
Alloc − This is the type of allocator object.
How can we access the last element of vector?
To access the last element of the vector we can use two methods:
Example
using back() function
#include <bits/stdc++.h>
using namespace std;
int main(){
vector<int> vec = {11, 22, 33, 44, 55};
cout<<"Elements in the vector before updating: ";
for(auto i = vec.begin(); i!= vec.end(); ++i){
cout << *i << " ";
}
// call back() for fetching last element
cout<<"\nLast element in vector is: "<<vec.back();
vec.back() = 66;
cout<<"\nElements in the vector before updating: ";
for(auto i = vec.begin(); i!= vec.end(); ++i){
cout << *i << " ";
}
return 0;
}Output
If we run the above code it will generate the following output −
Elements in the vector before updating: 11 22 33 44 55 Last element in vector is: 55 Elements in the vector before updating: 11 22 33 44 66
Example
using size() function
#include <bits/stdc++.h>
using namespace std;
int main(){
vector<int> vec = {11, 22, 33, 44, 55};
cout<<"Elements in the vector before updating: ";
for(auto i = vec.begin(); i!= vec.end(); ++i){
cout << *i << " ";
}
// call size() for fetching last element
int last = vec.size();
cout<<"\nLast element in vector is: "<<vec[last-1];
vec[last-1] = 66;
cout<<"\nElements in the vector before updating: ";
for(auto i = vec.begin(); i!= vec.end(); ++i){
cout << *i <<" ";
}
return 0;
}Output
If we run the above code it will generate the following output −
Elements in the vector before updating: 11 22 33 44 55 Last element in vector is: 55 Elements in the vector before updating: 11 22 33 44 66
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