Geeky

This is where most of my posts will be

Ethics in Software Engineering

Wayne Koorts Comments

I’d like to start by first talking about software engineering itself, and whether it can legitimately be called engineering. The Oxford English Dictionary defines “engineering” as:

The branch of science and technology concerned with the development and modification of engines (in various senses), machines, structures, or other complicated systems and processes using specialized knowledge or skills, typically for public or commercial use; the profession of an engineer. Freq. with distinguishing word.

By this definition I believe it’s fair to describe the design and creation of software as “software engineering” and I’m going to proceed with the rest of this post on that basis.

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JavaScript snippet: Remove base URL from link

Wayne Koorts 2 Comments

I needed this function this morning so I thought I’d share it in case someone else does too.

function RemoveBaseUrl(url) {
    /*
     * Replace base URL in given string, if it exists, and return the result.
     *
     * e.g. "http://localhost:8000/api/v1/blah/" becomes "/api/v1/blah/"
     *      "/api/v1/blah/" stays "/api/v1/blah/"
     */
    var baseUrlPattern = /^https?:\/\/[a-z\:0-9.]+/;
    var result = "";
    
    var match = baseUrlPattern.exec(url);
    if (match != null) {
        result = match[0];
    }
    
    if (result.length > 0) {
        url = url.replace(result, "");
    }
    
    return url;
}

Gentle Editing

Wayne Koorts Comments

Like many programmers, I’ve come to love Stack Overflow and the rest of the Stack Exchange network. Its unique Wiki / Blog / Forum blend creates a fantastic platform for knowledge sharing.

Thanks to its Wiki-like editing capabilities, quality sticklers like myself can get stuck in and help to smooth out some of the rough edges of the content base.

Unfortunately we geeks sometimes allow our egos to get the better of us, resulting in reasonably common, dreaded, edit wars.  To avoid these, I’ve come up with what I feel is a very gentle and respectful editing style which I’d like to share with you today.  My edits always take a fair bit of time, but I feel it’s worth the investment in the interests of the greater good.

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K&R – Solution to Exercise 1.23

Wayne Koorts 1 Comment

I’m working my way through The C Programming Language at the moment, and so far I’m loving C’s purity and leanness.

One of my few disappointments with the book is the lack of solutions to the exercises. The exercises are refreshingly challenging because the book isn’t aimed at beginning programmers. Unfortunately this means that the desire to validate one’s solutions is quite strong. Fortunately, Google had a solution to this problem: Richard Heathfield’s solutions site.

I just finished my solution to exercise 1.23 (“Remove all comments from a C program”) and I’m quite chuffed with it so thought I would share it here. Out of the multiple solutions provided on Richard’s site, mine was about the closest to following the guidelines as far as what knowledge one is supposed to have of C by that (early) point in the book (the only thing I cheated with is the use of break and continue – it would have just been quite ugly without those two small additions). Basically the solution is a state machine using if / else instead of more traditional switch methods as switch had not yet been introduced.

My solution deals with all the special cases I could think of, and even deals with the tricky sample input on Richard’s site, provided at the bottom of the solutions page for this exercise.

/*
 * K&R Exercise 1-23
 *
 * "Write a program to remove all comments from a C program. Don't
 *  forget to handle quoted strings and character constants properly.
 *  C comments don't nest."
 *
 */

#include <stdio.h>

int main()
{
    int c;
    int c2;
    int in_quotes = 0;
    int in_comment = 0;
    int current_quote;

    c = getchar();
    while (c != EOF)
    {
        if (!in_comment && !in_quotes)
        {
            if (c == '\'' || c == '"')
            {
                in_quotes = 1;
                current_quote = c;
                putchar(c);
            }
            else if (c == '/')
            {
                c2 = getchar();
                if (c2 != EOF && c2 == '*')
                {
                    in_comment = 1;
                }
                else
                {
                    putchar(c); /* Just a regular '/', so output it. */
                    c = c2;
                    continue;
                }
            }
            else
            {
                putchar(c);
            }
        }
        else if (in_comment)
        {
            /* Check for a closing comment. */
            if (c == '*')
            {
                c2 = getchar();
                if (c2 != EOF && c2 == '/')
                {
                    in_comment = 0;
                }
                else
                {
                    /* Don't advance to next character in stream. */
                    c = c2;
                    continue;
                }
            }
        }
        else if (in_quotes)
        {
            /* Skip over escaped chars. */
            if (c == '\\')
            {
                putchar(c);
                c = getchar();
            }
            else
            {
                /* Check for closing quote. */
                if (c == current_quote)
                    in_quotes = 0;
            }
            putchar(c);
        }

        c = getchar();
    }

    return 0;
}