Just finished the 22 min video of David Malan in the specs of pset8 and I feel like I just understood 10% or even less of what he said, Really scared now dont wanna quit on the last pset. What study material should I look into if I have problems in completing this pset or what functions do I need to really understand in the the distribution code , in order to complete this pset? Any help or hint or tip would really be appreciated


Congratulations on finishing Problem Set 7! :)

Problem Set 8 is a lot to learn all at once, but don't quit.

As with other Problem Sets, just break this one down into small steps and tackle each one at a time.

First, work on writing the import PHP script. It's easier than it looks.

It's a lot like those C programs you wrote a long time ago, the ones that indexed into the command-line argument vector argv. Except in PHP it will be called $argv!

It will also use the CS50 Library to connect to a database, which should be familiar now that you have completed Problem Set 7.

In pseudo-code:

#!/usr/bin/env php
    // TODO: import places from US.txt into mySQL db

    // display errors, warnings, and notices

    // CS50 Library

    // Validate arguments
    // open a filehandle to read data
    // US.txt is basically a CSV, but delimited by "\t" instead of ","
        // put it in the database
    // remember to close the filehandle

Once you have the locations in your database, move on to the next task.

Follow the Problem Specification closely. Do things one step at a time!

Do not attempt to understand everything all at once, or your head may explode.

Good luck!

  • I have just finished pset7 and started pset8 too. Pset8 does look daunting but I want to finish the course. I have written the php script for import but when I have tried to run import from the command line to import the US.txt csv file into the phpMyAdmin places table I keep getting the following error: Oct 22 '16 at 10:23
  • ./import: Permission denied Is there a problem with the permissions with the csv file or perhaps should the import file have a .php extension? I would appreciate some help with this because at the moment I am stuck and I'm unable to move forward with this pset. Oct 22 '16 at 10:33
  • @MarkEdwards: The problem is with the permissions on ./import, which should be set chmod 700. (User needs rwx, group and world don't need any permissions since this is a PHP command-line script.) You're seeing that error because the executable bit is not set +x for the user that's trying to execute the import. Also, the .php extension is optional here; the only reason to use it would be to tell the c9 editor in the Cloud9 IDE what sort of syntax highlighting and auto-completion to use. Oct 22 '16 at 12:59
  • I set the permissions on ./import to chmod 700 but now I'm getting the following error, from the command line: Fatal error: CS50 library requires bcmath or bmp extension module in /home/ubuntu/workspace/pset8/vendor/library50-php-5/CS50/CS50.php on line 48 Am I missing out something here in my import file php script file? Oct 22 '16 at 15:02
  • @MarkEdwards: I'm glad that you fixed your permissions. Your CS50 library error is a separate and unrelated problem. We should try to keep the solution with the relevant question, and not discuss it in the comments to another question. Oct 22 '16 at 22:15

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