In this shot, we will learn about vector::front()
function in C++.
The vector::front()
function is available in the <vector>
header file. This function returns a reference to the first element in the vector.
If we call the front()
function on a vector that contains no elements, then we will get a segmentation fault error.
The syntax of the vector::front()
function is given below:
T& front();
The vector::front()
function does not accept any parameters.
It returns a reference of the template-type object that points to the first element of the vector.
Let’s have a look at the code now.
#include <iostream>#include <vector>using namespace std;int main(){vector<int> vec;// cout << " The Frontmost element of an empty vector is: " << vec.front();vec.push_back(3);vec.push_back(4);vec.push_back(5);vec.push_back(6);vec.push_back(2);cout << " The Frontmost element of the vector is: " << vec.front();return 0;}
In line 1, we include the C++ standard header file for input/output stream (iostream
) which is used to read and write from streams.
In line 2, we include the header file for C++ standard vector
, which includes all the functions and operations related to the vector container.
In line 3, we use the standard (std
) namespace that means we use all the things within the std
namespace.
In line 7, we declare the integer type vector container named vec
.
In line 9, we call the front()
function on an empty vector. If you uncomment the line, then you will get a segmentation fault error as there is no element in the vector.
From line 11 to 15, we push back the different elements to the vector container vec
.
In line 17, we print the result of the function front()
, which returns the foremost element of the vector container and in this example, is the front-most element. Hence the output is 3.
So, in this way, we can easily get the first element present in the vector.