Git Repositories
Git Repositories
In CIS 300, start code for each assignment will be distributed via a Git repository. Git is a source control system integrated into Visual Studio 2022. Source control systems are powerful mechanisms for teams of programmers and other collaborators to manage multiple copies of various source files and other documents that all collaborators may be modifying. While CIS 300 does not involve teamwork, source control provides a convenient mechanism for distribution of code and submission of assignment solutions. In addition, as we will discuss later, source control provides mechanisms for accessing your code on multiple machines and for “checkpointing” your code.
At the heart of Git is the concept of a Git repository. A Git repository is essentially a folder on your local machine. As you make changes within this folder, Git tracks these changes. From time to time, you will commit these changes. If you see that you have gone down a wrong path, you can revert to an earlier commit. Git repositories may be hosted on a server such as GitHub. Various users may have copies of a Git repository on their own local machines. Git provides tools for synchronizing local repositories with the repository hosted on the server in a consistent way.
The above description is a bit of an oversimplification, as the folder comprising a local copy of a repository typically contains some files and/or folders that are not part of the repository. One example of such “extra” files might be executables that are generated whenever source code within the repository is compiled. However, when Visual Studio is managing a Git repository, it does a good job of including within the repository any files the user places within the folder comprising the repository.
For each lab and homework assignment in CIS 300, you will be provided a URL that will create your own private Git repository on GitHub. The only people who will have access to your GitHub repositories are you, the CIS 300 instructors, and the CIS 300 lab assistants. These repositories will initially contain start code and perhaps data files for the respective assignments. You will copy the repository to your local machine by cloning it. When you are finished with the assignment, you will push the repository back to GitHub and submit its URL for grading. In what follows, we will explain how to create and clone a GitHub repository. Later in this chapter, we will explain how to commit changes, push a repository, and use some of the other features of Git.
Before you can access GitHub, you will need a GitHub account. If you don’t already have one, you can sign up for one at github.com. At some point after you have completed the sign-up process, GitHub will send you an email asking you to verify the email address you provided during the sign-up process. After you have done this, you will be able to set up GitHub repositories.
For each assignment in CIS 300, you will be given an invitation URL, such as:
Over the next few sections, we will be working through a simple example based on the above invitation link. If you wish to work through this example, click on the above link. You may be asked to sign in to GitHub, but once you are signed in, you will be shown a page asking you to accept the assignment. Clicking the “Accept this assignment” button will create a GitHub repository for you. You will be given a link that will take you to that repository. From that page you will be able to view all of the files in the repository.
In order to be able to use this repository, you will need to clone it to your local machine. To do this, first open Visual Studio 2022, and click on the “Clone a Repository” button on the right. In your web browser, navigate to the GitHub repository that you wish to clone, and click on the “Code” button. This will display a URL - click on the button to its right to copy this URL to your clipboard. Then go back to Visual Studio and paste this URL into the text box labeled, “Repository location”. In the text box below that, fill in a new folder you want to use for this repository on your machine, then click the “Clone” button (if you are asked to sign in to GitHub, click the link to sign in through your web browser). This will copy the Git repository from GitHub into the folder you selected, and open the solution it contains.
The following sections give an overview of how to use Visual Studio to edit and debug an application, as well as how to use Git within Visual Studio to maintain the local Git repository and synchronize it with the GitHub repository.