For my latest project I need to shorten the URLs which I then put in a mysql database.
I now ran against a problem, because I don't know how to solve this. Basically, the shortened strings should look like this (I want to include lowercase letters, uppercase letters and numbers)
a
b
...
z
0
...
9
A
...
Z
aa
ab
ac
...
ba
So, 1. URl --> a. Stored in mysql.
Next time, a new url gets stored to --> b because a is already in the mysql database.
And that is it. But I don't have any idea. Could someone of you please help me out?
Edit: Formattted & Further explanation.
It is kinda like the imgur.com URL shortening service. It should continue like this until infinity (which is not needed, I think...)
You can use the following function (code adapted from my personal framework):
function Base($input, $output, $number = 1, $charset = 'abcdefghijklmnopqrstuvwxyz0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ')
{
if (strlen($charset) >= 2)
{
$input = max(2, min(intval($input), strlen($charset)));
$output = max(2, min(intval($output), strlen($charset)));
$number = ltrim(preg_replace('~[^' . preg_quote(substr($charset, 0, max($input, $output)), '~') . ']+~', '', $number), $charset[0]);
if (strlen($number) > 0)
{
if ($input != 10)
{
$result = 0;
foreach (str_split(strrev($number)) as $key => $value)
{
$result += pow($input, $key) * intval(strpos($charset, $value));
}
$number = $result;
}
if ($output != 10)
{
$result = $charset[$number % $output];
while (($number = intval($number / $output)) > 0)
{
$result = $charset[$number % $output] . $result;
}
$number = $result;
}
return $number;
}
return $charset[0];
}
return false;
}
Basically you just need to grab the newly generated auto-incremented ID (this also makes sure you don't generate any collisions) from your table and pass it to this function like this:
$short_id = Base(10, 62, $auto_increment_id);
Note that the first and second arguments define the input and output bases, respectively.
Also, I've reordered the charset from the "default" 0-9a-zA-Z to comply with your examples.
You can also just use base_convert() if you can live without the mixed alphabet case (base 36).
Related
In need of some help - am trying to analyse news articles.
I have a list of positive words and negative words. I am search the article contents for instances of the words a counting the up.
my problem is that the negative word list is a lot long that the positive so all the results a skewed to negative.
I am looking for a way to normalise the results so a positive word is weighted slightly against the negative to even out the fact that is a considerably high chance of finding a negative word. Unfortunately I have no idea where to start.
Appreciate you taking the time to read this.
Below is the code I have so far.
function process_scores($content)
{
$positive_score = 0;
for ($i = 0; $i < count($this->positive_words); $i++) {
if($this->positive_words[$i] != "")
{
$c = substr_count( strtolower($content) , $this->positive_words[$i] );
if($c > 0)
{
$positive_score += $c;
}
}
}
$negative_score = 0;
for ($i = 0; $i < count($this->negative_words); $i++) {
if($this->negative_words[$i] != "")
{
$c = substr_count( strtolower($content) , $this->negative_words[$i] );
if($c > 0)
{
$negative_score += $c;
}
}
}
return ["positive_score" => $positive_score, "negative_score" => $negative_score];
}
So I don't know php, but this seems less like a php question and more of a question of method. Right now when you analyze an article, you assign words as positive or negative based on whether or not they are in your dictionary, but because your dictionaries are of different sizes, you feel like this isn't giving you a fair analysis of the article.
One method you could try is to assign each word in the article a value. If a word does not exist in your dictionary, have the program prompt for manual interpretation of the word through the command line. Then decide whether the word is positive, negative, or neutral, and have the program add that word to the appropriate dictionary. This will be really annoying at first, but English speakers use roughly the same 2000 words for almost all of our conversation, so after a few articles, you will have robust dictionaries and not have to worry about skew because every single word will have been assigned a value.
I would suggest just throwing in a weighting factor to the output. The exact weighting is determined by trial and error. I went ahead and refactored your code since there was some repetition
<?php
class WordScore {
private $negative_words = [];
private $positive_words = [];
private $positive_weight = 1;
private $negative_weight = 1;
public function setScore(float $pos = 1, float $neg = 1) {
$this->negative_weight = $neg;
$this->positive_weight = $pos;
}
public function processScores($content) {
$positive_score = $this->countWords($content, $this->positive_words);
$negative_score = $this->countWords($content, $this->negative_words);
return [
"positive_score" => $positive_score * $this->positive_weight,
"negative_score" => $negative_score * $this->negative_weight
];
}
private function countWords( string $content, array $words, float $weight = 1 ) {
$count = 0;
foreach( $words as $word ) {
$count += substr_count( strtolower($content) , strtolower($word) );
}
return $count;
}
}
working example at http://sandbox.onlinephpfunctions.com/code/19b4ac3c12d35cf253e9fa6049e91508e4797a2e
I have already solved this (see code below) but I don't have a satisfactory name for the resulting function.Also, I would like to explore this problem more broadly but I do not know what I am searching for. I have tried "circular math", "clock problem" I even remember monads being used to address this principle but I cannot find where I saw that.
THE PROBLEM: Given an sequential set of numbers that go in a circle like a clock 1,2,3,4,5,6,7,8,9,10,11,12,1,2,3,4.. (or a color hue scale in my case) and given a distance (in integers) I want to calculate the resulting number on that circular series.
So if a clock shows 5 and I add 9 hours the result should be 2.
5+9=2 or 3-7=8
The question is what do I call this. Here it's the solution in PHP:
function circularmath($strExpression = "2+2" , $top = 355 ){
$result = 0;
if(preg_match('/^\d+[+-]\d+$/',$strExpression)){
list($n1,$op,$n2)=preg_split('/([+-])/',$strExpression, null, PREG_SPLIT_DELIM_CAPTURE);
$result =($op==="+")? $n1+$n2:$n1-$n2;
if($result < 0){
$result=$top+$result;
}elseif($result > $top){
$result=$result-$top;
}
}
return $result;
}
$foo = circularmath("352+4");
echo $foo;
Thanks to Thomas G and ggorlen. It is in fact Modular Arithmetic and it led to better code:
function mod($a, $n) {
return ($a % $n) + ($a < 0 ? $n : 0);
}
function circularmath($strExpression = "2+2" , $top = 355 ){
$result = null;
if(preg_match('/^\d+[+-]\d+$/',$strExpression)){
list($n1,$op,$n2)=preg_split('/([+-])/',$strExpression, null, PREG_SPLIT_DELIM_CAPTURE);
$result =($op==="+")? $n1+$n2:$n1-$n2;
$result = mod($result , $top) ;
}
return $result;
}
$foo = circularmath("352+4")."\n";
echo "f:".$foo;
I am trying to generate random voucher code applying the following rules:
Alphanumeric combination 5 characters in capital case (A-Z, 0-9, and take away 1, 0, I, O).
This is my try
<?php
function generateRandomString($length = 5) {
return substr(str_shuffle("23456789ABCDEFGHIJKMNPQRSTUVWXYZ"), 0, $length);
}
echo generateRandomString();
?>
but i am not sure if there is a better way of doing this
If you need to call this function lots of times, your current implementation will be very slow, because it uses much more calls of random function than it is necessary (if $length < 32). Also if your set of allowed characters is smaller than number of characters in the result, your current implementation will return wrong result too. And also your implementation does not allow repeating of characters in the result, but in the specification it is not forbidden to repeat characters.
A little more accurate solution is to use array_rand():
function generateRandomString($length = 5) {
$allowed = str_split('23456789ABCDEFGHIJKMNPQRSTUVWXYZ'); // it is enough to do it once
$res = '';
foreach (array_rand($allowed, $length) as $k)
$res .= $allowed[$k];
return $res;
}
function generateRandom($length = 5) {
$possibleChars = '123456789ABCDEFGHJKMNPQRSTUVWXYZ';
$rndString = '';
for ($i = 0; $i < $length; $i++) {
$rndString .= $possibleChars[rand(0, strlen($possibleChars) - 1)];
}
return $rndString;
}
echo generateRandom();
Here you can define the characters which you want to have in your random string.
The problem with your function is that any char will be just used 1 time per call. Its not really random. And the lenght of the random string would also be limited to the amount of characters you have.
For example: AAAAA is not possible with your function, with mine it is.
If you need a string longer than your charset, that method will fail. Please can you try the code below;
<?php
function generateRandomString($length = 5) {
$chars = "23456789ABCDEFGHIJKMNPQRSTUVWXYZ"; //Your char-set
$charArray = str_split($chars); //Your array representation of chars
$charCount = strlen($chars); //Your char-set length
$result = "";
//Loop throught required `$length`
for($i=1;$i<=$length;$i++)
{
$randChar = rand(0,$charCount-1); //Pick a random char in range of our chars
$result .= $charArray[$randChar]; //Concatenate picked char to result
}
return $result;
}
echo generateRandomString(75);
?>
Here is a working example: https://ideone.com/D1EQ9T
Hope this helps.
For an ecommerce site I want to generate a random coupon code that looks better than a randomly generated value. It should be a readable coupon code, all in uppercase with no special characters, only letters (A-Z) and numbers (0-9).
Since people might be reading this out / printing it elsewhere, we need to make this a simple-to-communicate value as well, perhaps 8-10 characters long.
Something like perhaps,
AHS3DJ6BW
B83JS1HSK
(I typed that, so it's not really that random)
$chars = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";
$res = "";
for ($i = 0; $i < 10; $i++) {
$res .= $chars[mt_rand(0, strlen($chars)-1)];
}
You can optimize this by preallocating the $res string and caching the result of strlen($chars)-1. This is left as an exercise to the reader, since probably you won't be generating thousands of coupons per second.
Try this:
substr(base_convert(sha1(uniqid(mt_rand())), 16, 36), 0, 10)
Why don't keep it simple?
<?php
echo strtoupper(uniqid());
?>
Always returns 13 character long uppercased random code.
You can use the coupon code generator PHP class file to generate N number of coupons and its customizable, with various options of adding own mask with own prefix and suffix. Simple PHP coupon code generator
Example:
coupon::generate(8); // J5BST6NQ
http://webarto.com/35/php-random-string-generator
Here you go.
function randr($j = 8){
$string = "";
for($i=0;$i < $j;$i++){
srand((double)microtime()*1234567);
$x = mt_rand(0,2);
switch($x){
case 0:$string.= chr(mt_rand(97,122));break;
case 1:$string.= chr(mt_rand(65,90));break;
case 2:$string.= chr(mt_rand(48,57));break;
}
}
return strtoupper($string); //to uppercase
}
If there are no security requirements for these, then you don't really need randomly generated codes. I would just use incremental IDs, such as those generated by whatever RDBMS you use. Optionally, if you have different types of coupons, you could prefix the codes with something, e.g.:
CX00019 QZ0001C
CX0001A QZ0001D
CX0001B QZ0001E
Alternately, you could even use dictionary words in the coupon, as such coupon codes are easier to remember and faster for users to type. Companies like Dreamhost use these for their promo codes, e.g.:
Promo60
NoSetupFee
YELLOWGORILLA82
Some of these are obviously human-created (which you might want to have the option of), but they can also be generated using a dictionary list. But even if they are randomly-generated nonsense phrases, the fact that the characters follow a logical pattern still makes it much more user-friendly than something like R7QZ8A92F1. So I would strongly advise against using the latter type of coupon codes just on the basis that they "look cool". Your customers will thank you.
$size = 12;
$string = strtoupper(substr(md5(time().rand(10000,99999)), 0, $size));
function generateCouponCode($length = 8) {
$chars = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ';
$ret = '';
for($i = 0; $i < $length; ++$i) {
$random = str_shuffle($chars);
$ret .= $random[0];
}
return $ret;
}
you can find a lot of function in php rand manual
http://php.net/manual/en/function.rand.php
i like this one
<?php
//To Pull 8 Unique Random Values Out Of AlphaNumeric
//removed number 0, capital o, number 1 and small L
//Total: keys = 32, elements = 33
$characters = array(
"A","B","C","D","E","F","G","H","J","K","L","M",
"N","P","Q","R","S","T","U","V","W","X","Y","Z",
"1","2","3","4","5","6","7","8","9");
//make an "empty container" or array for our keys
$keys = array();
//first count of $keys is empty so "1", remaining count is 1-7 = total 8 times
while(count($keys) < 8) {
//"0" because we use this to FIND ARRAY KEYS which has a 0 value
//"-1" because were only concerned of number of keys which is 32 not 33
//count($characters) = 33
$x = mt_rand(0, count($characters)-1);
if(!in_array($x, $keys)) {
$keys[] = $x;
}
}
foreach($keys as $key){
$random_chars .= $characters[$key];
}
echo $random_chars;
?>
$length = 9;
$code = (strtoupper(substr(md5(time()), 0, $length)));
Just Write
$voucher_no = date('ymd') . rand(1000, 9999);
while(SapItem::where('voucher_no', $voucher_no)->exists()){
$voucher_no = date('ymd') . rand(1000, 9999);
}
Output: 2204171447
There's a blog post comment on codinghorror.com by Paul Jungwirth which includes a little programming task:
You have the numbers 123456789, in that order. Between each number, you must insert either nothing, a plus sign, or a multiplication sign, so that the resulting expression equals 2001. Write a program that prints all solutions. (There are two.)
Bored, I thought, I'd have a go, but I'll be damned if I can get a result for 2001. I think the code below is sound and I reckon that there are zero solutions that result in 2001. According to my code, there are two solutions for 2002. Am I right or am I wrong?
/**
* Take the numbers 123456789 and form expressions by inserting one of ''
* (empty string), '+' or '*' between each number.
* Find (2) solutions such that the expression evaluates to the number 2001
*/
$input = array(1,2,3,4,5,6,7,8,9);
// an array of strings representing 8 digit, base 3 numbers
$ops = array();
$numOps = sizeof($input)-1; // always 8
$mask = str_repeat('0', $numOps); // mask of 8 zeros for padding
// generate the ops array
$limit = pow(3, $numOps) -1;
for ($i = 0; $i <= $limit; $i++) {
$s = (string) $i;
$s = base_convert($s, 10, 3);
$ops[] = substr($mask, 0, $numOps - strlen($s)) . $s;
}
// for each element in the ops array, generate an expression by inserting
// '', '*' or '+' between the numbers in $input. e.g. element 11111111 will
// result in 1+2+3+4+5+6+7+8+9
$limit = sizeof($ops);
$stringResult = null;
$numericResult = null;
for ($i = 0; $i < $limit; $i++) {
$l = $numOps;
$stringResult = '';
$numericResult = 0;
for ($j = 0; $j <= $l; $j++) {
$stringResult .= (string) $input[$j];
switch (substr($ops[$i], $j, 1)) {
case '0':
break;
case '1':
$stringResult .= '+';
break;
case '2':
$stringResult .= '*';
break;
default :
}
}
// evaluate the expression
// split the expression into smaller ones to be added together
$temp = explode('+', $stringResult);
$additionElems = array();
foreach ($temp as $subExpressions)
{
// split each of those into ones to be multiplied together
$multplicationElems = explode('*', $subExpressions);
$working = 1;
foreach ($multplicationElems as $operand) {
$working *= $operand;
}
$additionElems[] = $working;
}
$numericResult = 0;
foreach($additionElems as $operand)
{
$numericResult += $operand;
}
if ($numericResult == 2001) {
echo "{$stringResult}\n";
}
}
Further down the same page you linked to.... =)
"Paul Jungwirth wrote:
You have the numbers 123456789, in
that order. Between each number, you
must insert either nothing, a plus
sign, or a multiplication sign, so
that the resulting expression equals
2001. Write a program that prints all solutions. (There are two.)
I think you meant 2002, not 2001. :)
(Just correcting for anyone else like
me who obsessively tries to solve
little "practice" problems like this
one, and then hit Google when their
result doesn't match the stated
answer. ;) Damn, some of those Perl
examples are ugly.)"
The number is 2002.
Recursive solution takes eleven lines of JavaScript (excluding string expression evaluation, which is a standard JavaScript function, however it would probably take another ten or so lines of code to roll your own for this specific scenario):
function combine (digit,exp) {
if (digit > 9) {
if (eval(exp) == 2002) alert(exp+'=2002');
return;
}
combine(digit+1,exp+'+'+digit);
combine(digit+1,exp+'*'+digit);
combine(digit+1,exp+digit);
return;
}
combine(2,'1');