Zero Wind - Jamie Wong » php

UWAngel-CLI

Jamie Wong — Sun, 27 Dec 2009 07:10:03 +0000

Near the end of the semester, I was getting kind of tired of navigating UW-ACE so frequently through my browsing and opening all the different tabs to grab all the files I wanted. While all the pretty graphics make for a decent user interface, it reduces the speed of the service.

But aside from that, I like being able to do as much as I possibly can from the console.

So I made a Command Line Interface (CLI) for UW-ACE in php using cUrl. I built in on my Macbook Pro in Snow Leopard, but it should work just fine on any *nix machine, and possibly in Cygwin or other emulators.

As always, source is available on github: UWAngel-CLI @ Github.

Since I always like to post snippets of code from my projects that may be universally useful, I'll do that here too.

CLI Colour in PHP cli_colours.php included in the UWAngel-CLI source is just a collection of constants which allow you to print out colours in your CLI scripts.


$COLOR_BLACK = "\033[0;30m";
$COLOR_DARKGRAY = "\033[1;30m";
$COLOR_BLUE = "\033[0;34m";
$COLOR_LIGHTBLUE = "\033[1;34m";
$COLOR_GREEN = "\033[0;32m";
$COLOR_LIGHTGREEN = "\033[1;32m";
$COLOR_CYAN = "\033[0;36m";
$COLOR_LIGHTCYAN = "\033[1;36m";
$COLOR_RED = "\033[0;31m";
$COLOR_LIGHTRED = "\033[1;31m";
$COLOR_PURPLE = "\033[0;35m";
$COLOR_LIGHTPURPLE = "\033[1;35m";
$COLOR_BROWN = "\033[0;33m";
$COLOR_YELLOW = "\033[1;33m";
$COLOR_LIGHTGRAY = "\033[0;37m";
$COLOR_WHITE = "\033[1;37m";
$COLOR_DEFAULT = "\033[0;37m";
 
echo <<< EOT
One fish, 
two fish, 
{$COLOR_RED}red{$COLOR_DEFAULT} fish, 
{$COLOR_BLUE}blue{$COLOR_DEFAULT} fish.
 
EOT;
?>

The only gripe I have about this is that COLOR_DEFAULT it's the same colour as I have on by default in iTerm. Anyone know the escape code to make it actually revert to what it was before instead of just making an assumption about what color is being used?

Hide Commandline Input One of the first things I looked up when I started this project today was how to hide user input from the command line. I sure as hell didn't want people typing their passwords for UWACE on screen and having it actually display. It turns out you can do this by temporarily telling your TTY to stop echoing what you type. The command for this is "stty -echo" and can be re-enabled using "stty echo". Below is how I implemented as part of the AngelAccess class to meet my needs.

 function Prompt($prompt_text,$hide = false) {
     echo $prompt_text;
     $input = "";
     if ($hide) {
         $input = trim(`stty -echo;head -n1;stty echo`);
         echo "\n";
     } else {
         $input = trim(fgets(STDIN));
     }
     return $input;
 }

As a complete side note, thanks to a boot-camped installation of Windows 7 (or at least I'm fairly sure that's the culprit,) my Macbook Pro is now stuck on Digital Out. This means I can't use the internal speakers on my computer under Mac OS X. Well... what I should say is that I can't use them without some annoying tricks. If I plug in my headphones, then tell my mac to use the input jack for audio input, then my internal speakers appear under the output options and let me use them. The speakers then work perfectly fine. They also work fine under Windows 7. A direct side effect of digital out being stuck on is a read light emanating from the audio jack.

The problem is apparently fairly common, unfortunately the only confirmed fixes for it are sending it back to Apple or wiggling a toothpick around in the audio jack. I had absolutely no luck with the toothpick, or precision screwdriver, or pen cartridge, or paintbrush handle. If anyone knows how to fix this problem, I would love to know. Otherwise, I'm just going to take it into the Apple store in Rideau some time this week and hope they can fix the problem. I really don't want to have to send my Mac in during my first week at Velocity.

Omegle Voyeur – Multiple Connections

Jamie Wong — Sat, 14 Nov 2009 09:52:12 +0000

In case you haven't read the post about all my projects, here's a description of what Omegle Voyeur is:

Omegle is a website where you are connected to a stranger for a chat. It is dominated mostly by trolls whose primary purpose is to coerce you into a cyber session and then switch genders or to make you lose the game. Talking to these people is a rather tiresome endeavour, but seeing exactly what happens in these conversations is interesting. Omegle Voyeur is a way of watching a conversation which you aren't part of. What Voyeur does is form two simultaneous connections and then pass the input of one to the output of the other. This sets you up as a conversation proxy, allowing you to watch. Currently, this is exclusively a "sit and watch" program. Later I intend to add functionality to add more than 2 people into a conversation, automatically name the participants so it will be obvious that there are more than 2 people in the conversation, and allow the ability to interfere (mute participants/say things yourself) with a conversation. This concept was spawned during discussion (read: boredom) at CCC Stage 2, 2009.

In terms of technology, Omegle Voyeur is primarily one big Javascript Prototype class. Prototype is a Javascript Framework which makes the creation and maintenance of classes, conversion of data into JSON for transfer, and sending AJAX requests much, much easier.

There's also a very small bit of code in php which is able to be so short because it uses the incredible program cUrl. cUrl is a command line utility for grabbing data from websites using their URL. libcurl facilititates the use of curl in php without having to write your own wrapper.

Below is some php code I use to make curl even easier than it already is. simple_get($url) will return the HTTP GET result from the url specified. simple_post works similarly, but delivers data using the payload.


// Simple cUrl
// Simple get and post requests 
function simple_get($url) {
    $c = curl_init();
    curl_setopt($c, CURLOPT_URL, $url);
    curl_setopt($c, CURLOPT_RETURNTRANSFER, 1);
    $result = curl_exec($c);
    curl_close($c);
    return $result;
}
 
function simple_post($url,$payload) {
    $c = curl_init();
    curl_setopt($c, CURLOPT_URL, $url);
    curl_setopt($c, CURLOPT_POST, true);
    curl_setopt($c, CURLOPT_POSTFIELDS, $payload);
    curl_setopt($c, CURLOPT_RETURNTRANSFER, 1);
    $result = curl_exec($c);
    curl_close($c);
    return $result;
}
?>

When I started working on this project today (well, I suppose that would be last night now... wonder if I'll see the sunrise) I figured it would be a good time to get used to using git, so I made a repository using github. So far I'm enjoying git. Everything seems to act pretty much the way you'd expect to, and I already had to do a revert once I realized my logic was wrong for the way I was structuring my code.

You can see the github for Omegle Voyeur here: http://github.com/phleet/Omegle-Voyeur Feel free to design your own stuff with the all the code there - just be sure to link back here, or to the github page.

In any case, the thing the majority of the people reading this are probably interested in are the result. Things I've updated since last time are primarily aesthetic and behind the scenes, but I did add the ability to connect one person to more than one other person, and the connections don't have to be mutual. In the first 3 way conversation example, 1 can only speak to 2, 2 can only speak to 3 and 3 can only speak to 1. It leads to some rather confused people.

~~You can see the current running version here: Omegle Voyeur.~~ EDIT: It seems that after being posted on reddit, omegle has (manually?) IP blocked me. The source should still work, so feel free to try it out yourself. You can go grab XAMPP to run it locally. For the time being, you can view it here: Omegle Voyeur

A quick note on how I figured out the Omegle communication protocol. The entire code governing the process is conveniently kept here: http://omegle.com/static/omegle.js?27 Unless you enjoy reading 1000s of characters on a single line, you can use the JS Beautifier to clean it up to a readable state.

SPOJ Problem 2: Prime Generator (PRIME1)

Jamie Wong — Fri, 13 Nov 2009 05:47:34 +0000

Problem: Prime Generator

Peter wants to generate some prime numbers for his cryptosystem. Help him! Your task is to generate all prime numbers between two given numbers!

Concept The idea behind every solution here (with some variation) is to generate all the prime numbers that could be factors of numbers up to the maximum endpoint 1 billion. That square root happens to be around 32000. Using this array, do a bounded Sieve of Eratosthenes only in the range requested. In languages like php and python, it turns out that it's more efficient to build an associative array and check if the index is set than it is to generate a huge boolean array.

Code

C++

/// PRIME1 - C++ (g++)
// AC Time: 2.52s
// NOTE: I am aware that the use of vector and set actually
//  makes this code run _slower_
// I used vector and set simply as a way of practicing STL
#include 
#include 
#include 
#include 
using namespace std;
 
int main() {
    vector<int> primes;
    primes.push_back(2);
 
    for (int i = 3; i <= 32000; i+=2) {
        bool isprime = true;
        int cap = sqrt(i) + 1;
 
        vector<int>::iterator p;
        for (p = primes.begin(); p != primes.end(); p++) {
            if (*p >= cap) break;
            if (i % *p == 0) {
                isprime = false;
                break;
            }
        }
        if (isprime) primes.push_back(i);
    }
 
    int T,N,M;
 
    cin >> T;
 
    for (int t = 0; t < T; t++) {
        if (t) cout << endl;
 
        cin >> M >> N;
        if (M < 2) M = 2;
 
        int cap = sqrt(N) + 1;
 
        set<int> notprime;
        notprime.clear();
 
        vector<int>::iterator p;
        for (p = primes.begin(); p != primes.end(); p++) {
 
            if (*p >= cap) break;
            int start;
 
            if (*p >= M) start = (*p)*2;
            else start = M + ((*p - M % *p) % *p);
 
            for (int j = start; j <= N; j += *p) {
                notprime.insert(j);
            }
        }
 
        for (int i = M; i <= N; i++) {
            if (notprime.count(i) == 0) {
                cout << i << endl;
            }
        }
 
    }
    return 0;
}

C99

// PRIME1 - C99 (gcc)
// AC Time: 0.07s
#include 
#include 
#include 
#include 
 
int main() {
    int primes[4000];
    int numprimes = 0;
 
    primes[numprimes++] = 2;
    for (int i = 3; i <= 32000; i+=2) {
        bool isprime = true;
        int cap = sqrt(i)+1;
        for (int j = 0; j < numprimes; j++) {
            if (primes[j] >= cap) break;
            if (i % primes[j] == 0) {
                isprime = false;
                break;
            }
        }
        if (isprime) primes[numprimes++] = i;
    }
 
    int T,N,M;
    scanf("%d",&T);
 
    for (int t = 0; t < T; t++) {
        if (t) printf("\n");
        scanf("%d %d",&M,&N);
        if (M < 2) M = 2;
 
        int cap = sqrt(N) + 1;
 
        bool isprime[100001];
        memset(isprime,true,sizeof(isprime));    
 
        for (int i = 0; i < numprimes; i++) {
            int p = primes[i];
 
            if(p >= cap) break;
 
            int start;
 
            if (p >= M) start = p*2;
            else start = M + ((p - M % p) % p);
 
            for (int j = start; j <= N; j += p) {
                isprime[j - M] = false;
            }
        }
 
        int start = (M % 2)?M:M+1;    
 
        if (M == 2) {
            printf("2\n");
        }
        for (int i = start; i <= N; i+=2) {
            if (isprime[i-M]) printf("%d\n",i);
        }
    }
    return 0;
}

PHP


// PRIME1 - PHP
// AC Time: 5.73
 
$primes = array(2);
$numprimes = 1;
 
for ($i = 3; $i <= 32000; $i+=2) {
    $isprime = true;
    $cap = sqrt($i)+1;
 
    for ($j = 0; $j < $numprimes; ++$j) {
        if ($j >= $cap) break;
        if (!($i % $primes[$j])) {
            $isprime = false;
            break;
        }
    }
    if ($isprime) $primes[$numprimes++] = $i;
}
 
fscanf(STDIN,"%d",$T);
 
$output = "";
 
for ($t = 0; $t < $T; $t++) {
    if ($t) $output .= "\n";
 
    fscanf(STDIN,"%d %d",$M,$N);
    if ($M < 2) $M = 2;
 
    $isprime = array();
 
    $cap = sqrt($N)+1;
 
    $i = 0;
    while($i < $numprimes) {
        $p = $primes[$i];
 
        if ($p >= $cap) break;
 
        if ($p >= $M) {
            $start = $p*2;
        } else {
            $start = $M + (($p - $M % $p) % $p);
        }
 
        for ($j = $start; $j <= $N; $j += $p) {
            $isprime[$j - $M] = false;
        }
 
        ++$i;
    }
 
    for ($i = $M; $i <= $N; ++$i) {
        if (!isset($isprime[$i-$M])) {
            $output .= "$i\n";
        }
    }
}
 
echo $output;
?>

Python

# PRIME1 - Python
# AC Time: 3.10s
from math import sqrt
primes = [2]
 
for i in range(3,32000,2):
    isprime = True
 
    cap = sqrt(i)+1
 
    for j in primes:
        if (j >= cap):
            break
        if (i % j == 0):
            isprime = False
            break
    if (isprime):
        primes.append(i)
 
T = input()
output = ""
for t in range(T):
 
    if (t > 0):
        output += "\n"
 
    M,N = raw_input().split(' ')
    M = int(M)
    N = int(N)
    cap = sqrt(N)+1
 
    if (M < 2):
        M = 2
 
    isprime = [True]*100001
 
    for i in primes:
        if (i >= cap):
            break
 
        if (i >= M):
            start = i*2
        else:
            start = M + ((i - M % i)%i)
 
        # The two below, obscure lines create a continuous
        #  block of false elements in order to set all
        #  elements correspnding to numbers divisible by i
        #  in isprime to be false
        # In turns out that this runs substantially faster
        #  than setting the elements individually using loops
        falseblock = [False] * len(isprime[start-M:N+1-M:i]);
        isprime[start-M:N+1-M:i] = falseblock
 
    for i in range(M,N+1):
        if (isprime[i-M] == True):
            output += str(i) + "\n"
 
print output[:-1]

Bash

# PRIME1 Incomplete - BASH
# This is not a complete solution
# The speed of bash parsing makes getting an 
#  AC submission infeasible
 
# The following code is a working prime generator
# Giving enough time, it will output all prime 
#  numbers from 0 to 32000
# ..which is the first step in the solution to PRIME1
 
let PRIMES[0]=2
let NUMPRIMES=1
for i in {3..32000}; do
    let ISPRIME=1
 
    #for j in {0..$NUMPRIMES}; do
    for (( j = 0;j<$NUMPRIMES;j++ )); do
        let CURPRIME=${PRIMES[$j]}
        if [[ $CURPRIME*$CURPRIME -gt $i ]]; then
            break
        fi
 
        let MOD=$[$i % $CURPRIME]
        if [ $MOD -eq 0 ]; then
            let ISPRIME=0
            break
        fi
    done
 
    if [ $ISPRIME -eq 1 ]; then
        echo $i
        let PRIMES[NUMPRIMES]=$i
        let NUMPRIMES=NUMPRIMES+1
    fi
done

Ruby

# PRIME1 - Ruby
# AC Time: 4.65s
# 
# While I would have liked to use more
# Ruby idioms such as for p in primes
# or primes.each do |p| (used once),
# the difference in runtime between
# the use of loops like these and while
# loops was non-negligible
 
primes = [2]
 
3.step(32000,2) do |i|
    isprime = true
    cap = Math.sqrt(i) + 1
 
    primes.each do |p|
        if (p >= cap)
            break
        end
 
        if (i % p == 0)
            isprime = false
            break
        end
    end
 
    if isprime
        primes << i
    end
end
numprimes = primes.length
 
T = gets.to_i
 
 
output = ""
t = 0
while t < T
    print "\n" if t > 0
    line = gets.split(" ")
    m = line[0].to_i
    n = line[1].to_i
 
    m = 2 if m < 2
 
    cap = Math.sqrt(n) + 1
 
    notprime = {}
 
    i = 0
    while i < numprimes
        p = primes[i]
        i+=1
        if (p >= cap)
            break
        end
 
        if (p >= m)
            start = p*2
        else 
            start = m + ((p - m % p)%p)
        end
 
        j = start
        while j <= n
            notprime[j] = true
            j += p
        end
    end
 
    i = m
    while (i <= n)
        if (notprime[i] == nil)
            print i,"\n"
        end
        i+=1
    end
    t += 1
end

Java

// PRIME1 - Java
// AC Time: 2.20
 
import java.io.*;
import java.util.*;
import java.lang.Math.*;
 
public class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
 
        int[] primes = new int[4000];
        int numprimes = 0;
 
        primes[numprimes++] = 2;
        for (int i = 3; i <= 32000; i+=2) {
            boolean isprime = true;
            double cap = Math.sqrt(i) + 1.0;
 
            for (int j = 0; j < numprimes; j++) {
                if (j >= cap) break;
                if (i % primes[j] == 0) {
                    isprime = false;
                    break;
                }
            }
            if (isprime) primes[numprimes++] = i;
        }
 
 
        int T,N,M;
 
        T = in.nextInt();
 
        for (int t = 0; t < T; t++) {
            if (t > 0) System.out.println("");
 
            M = in.nextInt();
            N = in.nextInt();
 
            if (M < 2) M = 2;
 
            boolean[] isprime = new boolean[100001];
            for (int j = 0; j < 100001; j++) {
                isprime[j] = true;
            }
 
            for (int i = 0; i < numprimes; i++) {
                int p = primes[i];
                int start;
 
                if (p >= M) start = p*2;
                else start = M + ((p - M % p)%p);
 
                for (int j = start; j <= N; j += p) {
                    isprime[j - M] = false;
                }
            }
 
            for (int i = M; i <= N; i++) {
                if (isprime[i-M]) System.out.println(i);
            }
        }
    }
}

Perl

# PRIME1 - Perl
# AC Time: 4.28s
@primes = (2);
 
for ($i = 3; $i <= 32000; $i+=2) {
    $isprime = 1;
    $cap = sqrt($i) + 1;
    foreach $p (@primes) {
        if ($p >= $cap) { 
            last;
        }
        if ($i % $p == 0) {
            $isprime = 0;
            last;
        }
    }
    if ($isprime == 1) {
        push(@primes,$i)
    }
}
 
 
$T = ;
 
for ($t = 0; $t < $T; $t++) {
    if ($t > 0) {
        print "";
    }
 
    $in = ;
    @line = split(/ /,$in);
    $M = $line[0];
    $N = $line[1];
 
    if ($M < 2) {
        $M = 2;
    }
 
    $cap = sqrt($N) + 1;
 
    @isprime = ((1) x 100001);
 
    foreach $p (@primes) {
        if ($p >= $cap) {
            last;
        }
 
        if ($p >= $M) {
            $start = $p*2;
        } else {
            $start = $M + (($p - $M % $p) % $p);
        }
 
        for ($j = $start; $j <= $N; $j += $p) {
            $isprime[$j-$M] = 0;
        }
    }
 
    for ($i = $M; $i <= $N; $i++) {
        if ($isprime[$i-$M] == 1) {
            print "$i\n";
        }
    }
}

// PRIME1 - C# (gmcs)
// AC Time: 1.50s
 
using System;
class PRIME1 {
    static void Main() {
 
        int[] primes = new int[4000];
        int numprimes = 0;
 
        primes[numprimes++] = 2;
        for (int i = 3; i <= 32000; i+=2) {
            bool isprime = true;
            double cap = Math.Sqrt(i) + 1.0;
            for (int j = 0; j < numprimes; j++) {
                if (j >= cap) break;
                if (i % primes[j] == 0) {
                    isprime = false;
                    break;
                }
            }
            if (isprime) primes[numprimes++] = i;
        }
 
        int T,N,M;
        T = int.Parse(Console.ReadLine());
 
        for (int t = 0; t < T; t++) {
            if (t > 0) Console.WriteLine("");
 
            string[] parts = Console.ReadLine().Split(' ');
            M = int.Parse(parts[0]);
            N = int.Parse(parts[1]);
 
 
            if (M < 2) M = 2;
            double cap = Math.Sqrt(N)+1;
 
            bool[] isprime = new bool[100001];
            for (int i = 0; i < 100001; i++) isprime[i] = true;
 
            for (int i = 0; i < numprimes; i++) {
                int p = primes[i];
                if (p >= cap) break;
                int start;
 
 
                if (p >= M) start = p*2;
                else start = M + ((p - M % p)%p);
 
                for (int j = start; j <= N; j+= p) {
                    isprime[j - M] = false;
                }
            }
 
            for (int i = M; i <= N; i++) {
                if (isprime[i-M] == true) Console.WriteLine(i);
            }
        }
    }
}

GNU Pascal

{ 
    PRIME1 - GNU Pascal
    AC Time: 0.54
}
 
program PRIME1;
var
    primes: array[1..4000] of integer;
    numprimes: integer;
    i,j: integer;
    cap: double;
    isprime: boolean;
    T,N,M: integer;
    isp: array[0..100001] of boolean;
    p,start: integer;
 
 
begin
    primes[1] := 2;
    numprimes := 1;
    for i := 3 to 32000 do
    begin
        isprime := true;
        cap := sqrt(i) + 1;
        for j := 1 to numprimes do
        begin
            if primes[j] >= cap then 
                    break;
 
            if (i MOD primes[j] = 0) then
            begin
                isprime := false;
                break;
            end
        end;
 
        if isprime = true then 
        begin
            numprimes := numprimes + 1;
            primes[numprimes] := i
        end
    end;
 
    read(T);
 
    for t := 1 to T do
    begin
        if t > 0 then
            writeln('');
 
        read(M);
        read(N);
 
        if M < 2 then
            M := 2;
 
        cap := sqrt(N) + 1;
 
        for i := 0 to 100001 do
            isp[i] := true;
 
 
        for i := 1 to numprimes do
        begin
            p := primes[i];            
            if p >= cap then 
                break;
 
            if p >= M then
                start := (p * 2);
 
            if p < M then
                start := M + ((p - (M MOD p)) MOD p);
 
            j := start;
 
            while j <= N do
            begin
                isp[j - M] := false;
                j := j + p;
            end;
        end;
 
        for i := M to N do
        begin
            if isp[i-M] = true then
                writeln(i);
        end;
    end;
end.

SPOJ Problem 1

Jamie Wong — Sun, 08 Nov 2009 17:55:10 +0000

When I saw that Thor had done solutions to the first few problems of Project Euler in many many languages, I thought "Hey! That's a good idea!" but didn't want to copy exactly.

So instead I'm doing solutions to some problems on SPOJ. SPOJ is an online judge system full of algorithmic problems. This is one of the things that Hanson Wang did to get as good as he is. The solutions I'll be providing here are going to be very simple problems, so don't expect any magic. The beautiful thing about SPOJ is the sheer number of languages it will judge. I figured this was the perfect playground to make sure my code worked in all the languages I try.

Problem: Life, the Universe, and Everything

Your program is to use the brute-force approach in order to find the Answer to Life, the Universe, and Everything. More precisely... rewrite small numbers from input to output. Stop processing input after reading in the number 42. All numbers at input are integers of one or two digits.

Solutions - In order of frequency that I use the language