Related Tags

c++
communitycreator

# What is the vector.front() function in C++?

Harsh Jain

Ace your System Design Interview and take your career to the next level. Learn to handle the design of applications like Netflix, Quora, Facebook, Uber, and many more in a 45-min interview. Learn the RESHADED framework for architecting web-scale applications by determining requirements, constraints, and assumptions before diving into a step-by-step design process.

In this shot, we will learn about vector::front() function in C++.

### Introduction

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.

### Syntax

The syntax of the vector::front() function is given below:

T& front();

### Parameter

The vector::front() function does not accept any parameters.

### Return

It returns a reference of the template-type object that points to the first element of the vector.

### Code

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;
}
Use vector.front() function in C++

### Explanation

• 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, $3$ 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.

RELATED TAGS

c++
communitycreator

CONTRIBUTOR

Harsh Jain