why? When creating a branch with git branch, it doesn't work.

[lincoln]

I have the following doubt, when I create a new branch called dev: git branch "dev", and I make changes in this branch, they are also reflected in the main branch, which should not happen, because when changing branches, with git checkout main, there are also the changes I made in my dev branch, could someone give me a suggestion as to why this is happening.

I leave the screen shot, in case it helps.
As an example I only entered a comment in my main.cpp file, being in the dev branch, and as I commented above, when I switch to the main branch the comment also appears and indicates that there were changes in the main.cpp file, thanks in advance for your answers.

[JKSH]

@lincoln said in why? When creating a branch with git branch, it doesn't work.:

when I create a new branch called dev: git branch "dev", and I make changes in this branch, they are also reflected in the main branch

You did not make any changes in your "dev" branch. You only made changes in your local copy of the file.

If you want the changes to become part of the "dev" branch, then you must commit your change when the "dev" branch is checked out.

After you commit it, then git checkout main will no longer show the change.

[ChrisW67]

git branch dev creates a branch but does not switch your working copy to that branch. Follow up with one of git switch dev or git checkout dev.

You can create a branch and switch your working copy in one action git checkout -b dev

Edit: Actually @JKSH is closer to answering the particular issue.