# Problem Set 4

## What to Do

2. Run update50 in your codespace’s terminal window to ensure your codespace is up-to-date and, when prompted, click Rebuild now
3. Submit one of:
• Filter (Less) if feeling less comfortable
Getting Started

Start by clicking inside your terminal window, then execute cd by itself. You should find that its “prompt” resembles the below.

$ Click inside of that terminal window and then execute wget https://cdn.cs50.net/2022/fall/psets/4/filter-less.zip followed by Enter in order to download a ZIP called filter-less.zip in your codespace. Take care not to overlook the space between wget and the following URL, or any other character for that matter! Now execute unzip filter-less.zip to create a folder called filter-less. You no longer need the ZIP file, so you can execute rm filter-less.zip and respond with “y” followed by Enter at the prompt to remove the ZIP file you downloaded. Finally, right-click or control-click on the filter-less folder and click “Open in CS50 Lab”. You should see the specification for this problem on the left-hand side and its distribution code on the right-hand side. • Filter (More) if feeling more comfortable Getting Started Start by clicking inside your terminal window, then execute cd by itself. You should find that its “prompt” resembles the below. $

Click inside of that terminal window and then execute

wget https://cdn.cs50.net/2022/fall/psets/4/filter-more.zip

followed by Enter in order to download a ZIP called filter-more.zip in your codespace. Take care not to overlook the space between wget and the following URL, or any other character for that matter!

Now execute

unzip filter-more.zip

to create a folder called filter-more. You no longer need the ZIP file, so you can execute

rm filter-more.zip

and respond with “y” followed by Enter at the prompt to remove the ZIP file you downloaded. Finally, right-click or control-click on the filter-more folder and click “Open in CS50 Lab”. You should see the specification for this problem on the left-hand side and its distribution code on the right-hand side.

4. Submit one of:
• Recover
Getting Started

Start by clicking inside your terminal window, then execute cd by itself. You should find that its “prompt” resembles the below.

$ Click inside of that terminal window and then execute wget https://cdn.cs50.net/2022/fall/psets/4/recover.zip followed by Enter in order to download a ZIP called recover.zip in your codespace. Take care not to overlook the space between wget and the following URL, or any other character for that matter! Now execute unzip recover.zip to create a folder called recover. You no longer need the ZIP file, so you can execute rm recover.zip and respond with “y” followed by Enter at the prompt to remove the ZIP file you downloaded. Finally, right-click or control-click on the recover folder and click “Open in CS50 Lab”. You should see the specification for this problem on the left-hand side and its distribution code on the right-hand side. • Reverse Getting Started Start by clicking inside your terminal window, then execute cd by itself. You should find that its “prompt” resembles the below. $

Click inside of that terminal window and then execute

wget https://cdn.cs50.net/2022/fall/psets/4/reverse.zip

followed by Enter in order to download a ZIP called reverse.zip in your codespace. Take care not to overlook the space between wget and the following URL, or any other character for that matter!

Now execute

unzip reverse.zip

to create a folder called reverse. You no longer need the ZIP file, so you can execute

rm reverse.zip

and respond with “y” followed by Enter at the prompt to remove the ZIP file you downloaded. Finally, right-click or control-click on the reverse folder and click “Open in CS50 Lab”. You should see the specification for this problem on the left-hand side and its distribution code on the right-hand side.

5. Submit this form

If you submit both versions of Filter, we’ll record the higher of your two scores. If you submit both Recover and Reverse, we’ll similarly record the higher of your two scores.

## How to Get Help

• Browse or search for answers on Ed or post your own questions!
• Browse the CS50 Manual Pages for functions that might be useful.
• Watch Shorts for any topics that you still have questions about.

• Attend office hours!

• If you see any errors when compiling your code with make, focus first on fixing the very first error you see, scrolling up as needed. If unsure what it means, try asking help50 for help. For instance, if trying to compile filter, and
make filter

help50 make filter