CS50 Changelog

Language Updates

2021-08-17T15:26:18.945Z

In anticipation of fall semester, cli50 and CS50 IDE have been updated with some updated language support!

Java 16.0.2
Node 16.2.2
Python 3.9.6
Ruby 2.7.4

Changes to check50, submit50 Authentication

2021-08-14T01:00:00Z

Tools like check50 and submit50 rely on git, a popular tool for saving different versions of code, and GitHub, a popular website for saving those versions in the cloud. To push (i.e., save) your code to GitHub using git, it used to be possible to log into GitHub via a command line (as in a terminal window) using a GitHub username and password. As of August 13, 2021, that’s no longer possible, which means you can no longer use check50 or submit50 using your GitHub username and password either.

But you can still use check50 and submit50! You just need to log in a bit differently, either using SSH or a personal access token. Odds are you’ll find SSH more convenient.

See https://cs50.readthedocs.io/github/ for all details.

cli50 Upgraded to Ubuntu 20.04

2021-01-01T20:23:00.001Z

Just in time for the new year, cli50 has been upgraded from Ubuntu 18.04 to Ubuntu 20.04, just like CS50 IDE! Also included are:

Java 15
Node 15
Python 3.9
Ruby 2.7

Rubber Duck Debugging in CS50 IDE

2020-09-13T18:10:00.001Z

In addition to printf, debug50 (aka gdb), and valgrind, CS50 also introduces students to rubber duck debugging, a technique that involves talking to a rubber duck (or any inanimate, or even animate, object) about a bug in their code. In healthier times, students on campus even receive their very own ddb. By explaining the intended logic of their code, any illogic therein tends to stand out, thereby enabling students to debug their code.

With everyone taking CS50 online this term, we thought we’d provide everyone with their own virtual duck! And so, thanks to CS50’s own Kareem Zidane, Sophie Anderson, and Brenda Anderson, CS50 IDE now has its own clickable duck to whom students can talk via chat. To be fair, its vocabulary is limited, but what matters is students’ side of the conversation!

Linking to Chapters

2020-08-13T13:37:00.001Z

So that teachers (and we!) can link to specific chapters within CS50’s videos, the links in the Chapters menu now include not only start parameters but also end parameters as well. That way, if you control- or right-click on a chapter and copy its URL, you can link to just a single chapter; the player will start playing the video at start and will automatically pause it at end. Consider, for instance, this link to a chapter on Pseudocode, which starts at 1700 seconds and ends at 1878 seconds!

https://video.cs50.io/jjqgP9dpD1k?screen=w3XNssqYBSU&start=1700&end=1878

You can also use the form on the player’s landing page at https://video.cs50.io/ to create URLs manually!

Snacks for Lectures

2020-06-20T12:24:00.001Z

A tradition in CS50 is to serve cake (or cupcakes) after the course’s first lecture. And that tradition has since evolved into snacks in the middle of every lecture. Of course, those snacks don’t readily translate to video, and such comments as these online have not been uncommon:

But no longer! Happy to say that the CS50 Video Player now includes a menu of snacks, complete with cake and healthier options alike!

Eat your vegetables!

An API for Harvard's Map

2020-06-03T18:00:00.001Z

Years ago, CS50 had an API (application programming interface) for Harvard’s map, so that students could integrate maps of campus into their own final projects. The API eventually fell by the wayside as CS50’s infrastructure evolved, but, now, that API is back!

Via a simple HTTP-based API can students now search for buildings like Wigglesworth Hall via simple GET requests. For instance, https://cs50.readthedocs.io/api/map/ will return JSON like:

[
{
"address": "6 Harvard Yard",
"city": "Cambridge",
"geometry": {
"point": [
-71.1162317399999,
42.3728310430001
],
"polygons": [
[
[
-71.11589956799997,
42.37279049500006
],
[
-71.11594347499994,
42.372702323000055
],
[
-71.11600147799999,
42.37271820400008
],
[
-71.11600269399997,
42.37271576400008
],
[
-71.11610170199998,
42.37274287200006
],
[
-71.11610013999996,
42.37274601000007
],
[
-71.11640570199995,
42.372829671000034
],
[
-71.11640749999998,
42.37282606200006
],
[
-71.11650843499996,
42.37285369800003
],
[
-71.11650663799998,
42.37285730600007
],
[
-71.11656312399998,
42.37287277200005
],
[
-71.11652030599998,
42.37296030500005
],
[
-71.11589956799997,
42.37279049500006
]
]
]
},
"id": 997,
"image": "https://devsmap.cadm.harvard.edu/images/root_images/03323.jpg",
"name": "Wigglesworth Hall, Entries A,B,C+D"
},
{
"address": "6 Harvard Yard",
"city": "Cambridge",
"geometry": {
"point": [
-71.117157489,
42.373083326
],
"polygons": [
[
[
-71.11674415099998,
42.37302187700004
],
[
-71.11676889299997,
42.37297193200004
],
[
-71.11678784399999,
42.37293177000004
],
[
-71.11679359399994,
42.37293354600007
],
[
-71.11684414499996,
42.37294797100003
],
[
-71.11684574399999,
42.37294474200007
],
[
-71.11694710199998,
42.37297234700003
],
[
-71.11694550299995,
42.372975576000044
],
[
-71.11740777999995,
42.37310117900006
],
[
-71.11741015999996,
42.37309832700004
],
[
-71.11750781999996,
42.37312492400008
],
[
-71.11750300299997,
42.37312714900003
],
[
-71.11757062399994,
42.37314577600006
],
[
-71.11752645499996,
42.37323494200007
],
[
-71.11674415099998,
42.37302187700004
]
]
]
},
"id": 1159,
"image": "https://devsmap.cadm.harvard.edu/images/root_images/03322.jpg",
"name": "Wigglesworth Hall, Entries E,F,G,H+I"
},
{
"address": "6 Harvard Yard",
"city": "Cambridge",
"geometry": {
"point": [
-71.117856715,
42.3732810010001
],
"polygons": [
[
[
-71.11770292099999,
42.37328923700005
],
[
-71.11774775899994,
42.37320090400004
],
[
-71.11800155099996,
42.37327055600008
],
[
-71.11801092199994,
42.37327307900006
],
[
-71.11796559599998,
42.373360913000056
],
[
-71.11770292099999,
42.37328923700005
]
]
]
},
"id": 1449,
"image": "https://devsmap.cadm.harvard.edu/images/root_images/03321.jpg",
"name": "Wigglesworth Hall, Entries J+K"
}
]

In addition to providing students’ with each building’s address, city, id, image, and name, the API also provides a building’s geometry, the value of which includes a point for that building (e.g., its centroid) and also one or more polygons, which collectively describe the building’s footprint.

UI Improvements for CS50 Video Player

2020-06-03T00:00:00.001Z

CS50’s video player, a web app at video.cs50.io that synchronizes instructional videos with screen recordings, is now all the more responsive, particularly when embedded in a course’s website:

The “Keyboard” in “Keyboard Shortcuts” has been replaced with an icon to free up horizontal space.
A pop-out icon has been added (when the player is embedded) so that students can pop the player out into the full window.
“CS50 Video Player” is shortened to “CS50” on the smallest of screens.

Screenshots below!

In terms of other features and bug fixes:

The Escape key will now close the Captions drop-down.
A bug was fixed whereby clicking Screen when a video is paused would result in a spinning icon.
A bug was fixed whereby, if a student seeked in a video while Screen was enabled, the main video wouldn’t stay synchronized.

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Medium

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Docs for CS50's Dining API Have Moved

2020-06-02T02:00:00.001Z

Documentation for CS50’s Dining API, which provides Harvard students with programmatic access via HTTP to data from Harvard University Dining Services, has been integrated to cs50.readthedocs.io, where CS50’s other documentation lives.

While the documentation no longer includes Try It buttons (which seemed unnecessary for a GET-only API), it does still include tabbed code examples for Python and cURL. And it’s (hopefully!) a bit easier to read.

See cs50.readthedocs.io/api/dining for its new home. Screenshot below!

Theme for CS50's Docs Updated

2020-06-02T00:00:00.001Z

The theme for CS50’s documentation at cs50.readthedocs.io has been updated to the latest version of sphinx_rtd_theme. The UI is largely the same, though we’ve tweaked a few aesthetics. Most compelling, though, the latest version of the theme has simplified the documentation’s conf.py and obviated the need for most of the site’s custom CSS.

We’ve also enabled an Edit on GitHub link atop each page to make it easier for folks to open a pull request to propose corrections or improvements to the documentation.

Screenshot below!