Difference between vectors in C++

By Md Shoriful Islam

Difference between vectors in C++

Difference between vectors in C++

In C++, the vector is a dynamic array that can grow in size. The three declarations you’ve provided are different ways to declare a vector, and here’s what each one means:

  1. vector<int> result;
  • This declares a vector named result that will store integers (int). Initially, it is empty, and its size will grow dynamically as integers are added to it.

2. vector<int> result[10];

  • This is actually an array of vectors. It declares an array named result with 10 elements, where each element is a vector that can store integers. Each vector in the array can grow independently in size.

3. vector<int> result(nums.size());

  • This declares a vector named result that will store integers, and it is initialized to have a size equal to nums.size(). Assuming nums is another vector, result will have the same number of elements as nums from the start.

In summary:

  • The first declaration is a single vector with a dynamic size.
  • The second is an array of 10 vectors, each with a dynamic size.
  • The third is a single vector whose initial size is set to the size of another vector, nums.

Here’s how you might visualize the differences:


    // A single empty vector that can grow dynamically.
vector<int> result;
    // An array of 10 vectors, each can grow dynamically.
vector<int> result[10];
    // A single vector initialized to the size of 'nums'.
vector<int> result(nums.size());
 

Remember, the second declaration is not a vector but an array of vectors, which is a common point of confusion. The third declaration assumes that nums is a previously defined vector and uses its size to initialize the result vector. I hope this clarifies the differences for you! If you have any more questions or need further explanation, feel free to ask.

Comments

Anonymous said…
good
May 1, 2024 at 11:21 PM

Post a Comment

Popular posts from this blog

Whiteboarding Interviews

By Md Shoriful Islam
Image
 ⭕ Whiteboarding interviews are a common way of assessing the technical and non-technical skills of candidates for software development positions. They involve solving a coding problem or designing a system on a whiteboard, either in person or virtually, while explaining your approach and reasoning to the interviewer.  ⭕ Some of the benefits of whiteboarding interviews are that they can test your problem-solving ability, communication skills, and coding proficiency in a realistic scenario. They can also help you demonstrate your creativity, collaboration, and passion for the role. However, some of the drawbacks of whiteboarding interviews are that they can be stressful, artificial, and biased. They can also favor memorization over understanding and overlook other aspects of your skills and experience.  ⭕ If you want to ace a whiteboarding interview, you should practice beforehand, prepare for the interview setting, set objectives and expectations, create a good candidate ...
Read more

Version Control with Git: A Beginner’s Guide

By Md Shoriful Islam
Version Control with Git: A Beginner’s Guide If you are a developer, you probably know how important it is to keep track of your code changes and collaborate with other developers on a project. But how do you do that effectively and efficiently? The answer is version control. Version control is a system that records changes to a file or set of files over time so that you can recall specific versions later. It allows you to revert files back to a previous state, compare changes over time, see who last modified something, and more. Version control also enables you to work with other developers on the same code base without stepping on each other’s toes. One of the most popular version control systems in the world is Git. Git is a free and open source distributed version control system that is designed to handle everything from small to very large projects with speed and efficiency. Git has many features that make it superior to other version control systems, such as: Cheap local branchin...
Read more

Callback function in JavaScript

By Md Shoriful Islam
Image
Callback function in JavaScript What is a callback function in JavaScript? A callback function is a function that is passed as an argument to another function and is executed after the first function has completed its task. Callback functions are useful for handling asynchronous events, such as network requests, file operations, or timers. For example, you can use a callback function to display the result of a calculation after the calculation is done. Callback function in JavaScript Here is a simple example of a callback function in JavaScript: // Define a function that takes a callback as an argument function sayHello (callback) { // Do some task console .log ("Hello, world!"); // Invoke the callback function callback (); } // Define another function function sayGoodbye () { // Do some task console .log ("Goodbye, world!"); } // Call the first function and pass the second function as a callback sayHello (sayGoodbye); // The output will be: // Hello, wo...
Read more