Heather M’s Answer
There are definitely different days and it varies by company and production methodology, of course. I'll give some general examples!
Typically, a software project's features are broken down into smaller tasks by the management team and leads, which include specific milestones that groups of smaller tasks build up to. Beta is an example of a typical milestone.
Often, a lead gives tasks to individual engineers, based on what the goals are for the current milestone. So on a particular day, you might come in and assess what the highest priority task is on your list and get started coding it. Some tasks might actually span multiple days, in which case you'd give updates to your lead as they check in with you. You'll also need to collaborate with the rest of the team. Modern software is never a one-person job, so be prepared to communicate and work closely with other engineers.
Your team might also have code review days, in which everyone looks over your code as a group and gives feedback about how you can code more efficiently, etc.
Throughout production, you are also likely to have bug-hunting days, in which your day is dedicated to fixing problems with the software. Sometimes you may be using the software over and over again to see if your fix worked or if anything else broke in the process. Most teams have dedicated quality assurance testers, but the engineers often join in at key points to help ensure the best product goes out in the end.
So while your primary job may be coding, you might also end up with reviews, meetings, bug-hunting, and QA days, to name a few.
It's also important to note that the milestones are often on hard deadlines, so if things fall behind, engineers may work extra to meet the milestone regardless, depending on the company and product.
Overall, expect the standard federal allotment for meals and breaks.