Vector Operator = in C++ STL

Vector Operator = in C++ STL

Last Updated : 25 Nov, 2024

In C++, the vector operator = is used to assign the contents of one vector to another. It allows you to copy elements from one vector to another or initialize a vector with another vector's contents.

Let’s take a look at a simple code example:

C++

#include <bits/stdc++.h>
using namespace std;

int main() {
    vector<int> v1 = {1, 2, 3, 5, 4};
    vector<int> v2;

    // Assign contents of v1 to v2
    v2 = v1;

    for (int i : v2)
        cout << i << " ";
    return 0;
}

Output

1 2 3 5 4

Explanation: The contents of vector v1 are copied to vector v2. After the assignment, v2 contains the same elements as v1.

This article covers the syntax, usage, and common examples of vector operator = in C++:

Table of Content

Syntax of Vector operator =
Examples of Vector operator =

Assign One Vector to Another
Replace a Vector
Assign an Empty Vector

Syntax of Vector operator =

v2 = v1;

The destination vector (left operand) will be modified to contain the same elements as the source vector (right operand).

Note: The containers should be of same types, an error is thrown.

Examples of Vector operator =

The below examples demonstrate the common usage of the vector operator = in C++.

Assign One Vector to Another

C++

#include <bits/stdc++.h>
using namespace std;

int main() {
    vector<int> v1 = {1, 2, 3, 5, 4};
    vector<int> v2;

    // Assigning v1 to v2
    v2 = v1;

    for (int i : v2)
        cout << i << " ";
    return 0;
}

Output

1 2 3 5 4

Replace a Vector

C++

#include <bits/stdc++.h>
using namespace std;

int main() {
    vector<int> v1 = {1, 2, 3};
    vector<int> v2 = {9, 8, 7};

    // Reassign v1 to v2
    v2 = v1;

    for (int i : v2)
        cout << i << " ";
    return 0;
}

Output

1 2 3

Assign an Empty Vector

C++

#include <bits/stdc++.h>
using namespace std;

int main() {
    vector<int> v1 = {1, 2, 3};
    vector<int> v2;

    // Assign an empty vector to v1
    v1 = v2;

    if (v1.empty())
        cout << "v1 is now empty.";
    return 0;
}

Output

v1 is now empty.

Vector Operator = in C++ STL

A

abhishekcpp

Improve

Article Tags :

Practice Tags :

Similar Reads

C++ Programming Language

C++ is a computer programming language developed by Bjarne Stroustrup as an extension of the C language. It is known for is fast speed, low level memory management and is often taught as first programming language. It provides:Hands-on application of different programming concepts.Similar syntax to

Object Oriented Programming in C++

Object Oriented Programming - As the name suggests uses objects in programming. Object-oriented programming aims to implement real-world entities like inheritance, hiding, polymorphism, etc. in programming. The main aim of OOP is to bind together the data and the functions that operate on them so th

Inheritance in C++

The capability of a class to derive properties and characteristics from another class is called Inheritance. Inheritance is one of the most important features of Object-Oriented Programming in C++. In this article, we will learn about inheritance in C++, its modes and types along with the informatio

30 OOPs Interview Questions and Answers [2025 Updated]

Object-oriented programming, or OOPs, is a programming paradigm that implements the concept of objects in the program. It aims to provide an easier solution to real-world problems by implementing real-world entities such as inheritance, abstraction, polymorphism, etc. in programming. OOPs concept is

Vector in C++ STL

C++ vector is a dynamic array that stores collection of elements same type in contiguous memory. It has the ability to resize itself automatically when an element is inserted or deleted.Create a VectorBefore creating a vector, we must know that a vector is defined as the std::vector class template i

Templates in C++

C++ template is a powerful tool that allows you to write a generic code that can work with any data type. The idea is to simply pass the data type as a parameter so that we don't need to write the same code for different data types.For example, same sorting algorithm can work for different type, so

Operator Overloading in C++

in C++, Operator overloading is a compile-time polymorphism. It is an idea of giving special meaning to an existing operator in C++ without changing its original meaning.In this article, we will further discuss about operator overloading in C++ with examples and see which operators we can or cannot

C++ Classes and Objects

In C++, classes and objects are the basic building block that leads to Object-Oriented programming in C++. We will learn about C++ classes, objects, look at how they work and how to implement them in our C++ program.C++ ClassesA class is a user-defined data type, which holds its own data members and

C++ Interview Questions and Answers (2025)

C++ - the must-known and all-time favourite programming language of coders. It is still relevant as it was in the mid-80s. As a general-purpose and object-oriented programming language is extensively employed mostly every time during coding. As a result, some job roles demand individuals be fluent i

C++ Polymorphism

The word polymorphism means having many forms. A real-life example of polymorphism is a person who at the same time can have different characteristics. A man at the same time is a father, a husband, and an employee. So, the same person exhibits different behaviour in different situations. This is ca