I have following PHP script which I call via CLI:
#!/usr/bin/php
<?php
$max_stellen = 10;
for ($base=2; $base<=62; $base++) {
for ($power=2; $power<=10; $power++) {
$result = array();
$max_base = gmp_pow($base, $max_stellen);
$x = gmp_init(0);
while ((gmp_cmp($x, $max_base) == -1)) {
$val = gmp_strval($x, $base);
$i = strlen($val);
$left = gmp_pow($x, $power);
$right = gmp_pow($base, $i);
$mod = gmp_mod($left, $right);
if (gmp_cmp($mod, $x) == 0) {
$result[] = $val;
}
unset($left);
unset($right);
unset($mod);
$x = gmp_add($x, 1); // !!! line 30
}
unset($x);
unset($max_base);
$res2 = array();
foreach ($result as &$r) {
$root = substr($r, -1);
$res2[$root][] = $r;
}
unset($result);
foreach ($res2 as $root => &$r) {
echo "X^${power}_${base}($root) = {".implode(', ', $r)."}\n";
}
unset($res2);
echo "\n";
}
}
After a short time (values base=6, power=9), I get following error message:
PHP Warning: gmp_add(): -2147483648 is not a valid GMP integer resource in ... on line 30
If I manually run the code with base=6, power=9, it works, so the error only happens when the loop is running multiple times.
The error message sounds like there are GMP handles allocated which are not freed when they are not used anymore. So after a short time, the handle is out of integer range. But how do I free GMP handles? I already tried to use unset() everywhere, and functions like gmp_free() or gmp_destroy() do not exist.
Update
Reported issue to PHP, since I believe that it is not an expected behavior: https://bugs.php.net/bug.php?id=69702
Related
I am working on taxi app, after ride completes i have to draw map for which i use google map apis. let suppose my way-points are
array($coordinates1,$coordinates2,$coordinates3,$coordinates4,$coordinates5,$coordinates6,.........,$coordinates40)
the problem is that google map api accept only maximum of 23 way-points, for this purpose I have to skip many coordinates to pass, here my idea is to unset elements of array with equal intervals so that the route remain same. Please someone guide me how to remove many number of elements from an array with equal interval, just like i need 23 and total elements are 40 so that i need like
array($coordinates1,$coordinates4,$coordinates7,$coordinates9,$coordinates13,$coordinates16,.........,$coordinates39)
I have found a possible way, its a little bit lengthy but i got exact required result
$required_elements = 23;
$way = array();
for($ini=1;$ini<=78;$ini++)
{
$way[] = "Co-Ordinated:".$ini;
}
$total_elements = count($way);
list($way1, $way2) = array_chunk($way, ceil(count($way) / 2));
$differrence_element = $total_elements-$required_elements;
$skip_element = ceil($total_elements/$differrence_element);
$output = array();
if($total_elements > $required_elements)
{
$i=1;$j=0;
foreach($way as $x)
{
if($i == $skip_element)
{
$i=1;$j++;
continue;
}
else
{
$output[] = $way1[$j];
if(count($output) >= $required_elements) break;
$output[] = $way2[$j];
if(count($output) >= $required_elements) break;
$i++;$j++;
}
}
}
else
{
$output = $way;
}
$output1 = array();
$output2 = array();
$i=0;
foreach($output as $g)
{
if($i%2 == 0)
$output1[] = $g;
else
$output2[] = $g;
$i++;
}
$result = array_merge($output1,$output2);
print_r($way);
echo "<br><br><pre>";
print_r($result);
echo '</pre>';
I'm reading overflow for years but never had to post anything (thanks to great answers) until now because i can't rly find solution for my problem.
I'm kinda new to PHP.
So I'm creating game where you have to find a longest word with 12 random generated letters. I actually did this successfully in C# and Java, but now I'm porting some of code to PHP because i'm working on multiplayer version and some stuff will be on server.
So i did all this using this great thread (Answer by Thomas Jungblut):
Find the longest word given a collection
Now i tried to do same in PHP but, it's weird for me. I get some crazy result's and i dont know how to replicate this java method in php:
arraycopy(Object src, int srcPos, Object dest, int destPos, int length)
I'm not getting any error, but obvisuly thing is not working, is there anyone that can maybe help me to work this out?
UPDATE: BTW, i know post might be confusing im new to posting here...so forgive me ^^
I "fixed" code, it will now find me longest word. But there is bug somewhere. Bug is allowing algortithm to use one character more than once, which should not be possible.
I think problem is here:
$newDict[$index] = array_splice($allowedCharacters, $index +1, count($allowedCharacters) - ($index +1));
This is my Current Code:
parse_dictionary.php
<?php
$ouput = array();
$mysqli = new mysqli('localhost','root','','multiquiz_db');
$mysqli->set_charset('utf8');
if ($result = $mysqli->query("SELECT word FROM words_live")) {
while($row = $result->fetch_array(MYSQL_ASSOC)) {
//echo(mb_convert_encoding($row['word'], 'HTML-ENTITIES', 'utf-8'));
array_push($ouput, $row['word']);
}
//echo utf8_decode(json_encode($ouput));
}
$result->close();
$mysqli->close();
?>
Trie.php
<?php
class Trie
{
public $children = array();
public $value = null;
public $word = null;
public function __construct($value = null)
{
$this->value = $value;
}
public function adda($array)
{
$this->addb($array, 0);
}
public function addb($array, $offset)
{
foreach ($this->children as $child)
{
if($child->value == $array[$offset])
{
$child->addb($array, $offset + 1);
return;
}
}
$trieNode = new Trie($array[$offset]);
array_push($this->children, $trieNode);
if($offset < count($array) - 1)
{
$trieNode->addb($array, $offset+1);
}
else
{
$trieNode->word = implode(" ", $array);
}
}
}
?>
Index.php
<?php
include 'Trie.php';
include 'parse_dictionary.php';
ini_set('memory_limit', '1024M'); // or you could use 1G
header('Content-Type: text/html; charset=utf-8');
mb_internal_encoding("UTF-8");
class LongestWord
{
public $root = null;
public function __construct($ouput)
{
$this->root = new Trie();
foreach ($ouput as $word)
{
//echo($word);
//echo(str_split_unicode($word)[0]);
$this->root->adda(str_split_unicode($word));
}
}
public function search($cs)
{
return $this->visit($this->root, $cs);
}
function visit($n, $allowedCharacters)
{
$bestMatch = null;
if(count($n->children) == 0)
{
$bestMatch = $n->word;
}
foreach($n->children as $child)
{
if($this->contains($allowedCharacters, $child->value))
{
$result = $this->visit($child, $this->remove($allowedCharacters, $child->value));
if($bestMatch == null || $result != null && strlen($bestMatch) < strlen($result))
{
$bestMatch = $result;
}
}
}
return $bestMatch;
}
function remove($allowedCharacters, $value)
{
$newDict = $allowedCharacters;
if(($key = array_search($value, $newDict)))
{
unset($newDict[$key]);
}
return $newDict;
}
function contains($allowedCharacters, $value)
{
foreach($allowedCharacters as $x)
{
if($value == $x)
{
// echo $value . "=====". $x. "|||||||";
return true;
}
else
{
//echo $value . "!!===". $x. "|||||||";
}
}
return false;
}
}
function str_split_unicode($str, $l = 0) {
if ($l > 0) {
$ret = array();
$len = mb_strlen($str, "UTF-8");
for ($i = 0; $i < $len; $i += $l) {
$ret[] = mb_substr($str, $i, $l, "UTF-8");
}
return $ret;
}
return preg_split("//u", $str, -1, PREG_SPLIT_NO_EMPTY);
}
$chars = 'IIOIOFNČGDĆJ';
$testCharacters = str_split_unicode($chars);
$lw = new LongestWord($ouput);
echo($lw->search($testCharacters));
?>
As you're using MySQL, here's an approach that will let the DB server do the work.
It's a bit dirty, because you have to add several WHERE conditions with regex matching, which will have a rather poor performance. (Unfortunately, I could not come up with a regex that would require all of the letters in one expression, but I'd be happy to be corrected.)
However, I have tested it on a database table of >200000 entries; it delivers results within less than 0.3 sec.
SELECT word
FROM words_live
WHERE
word REGEXP "a" AND
word REGEXP "b" AND
word REGEXP "c" AND
word REGEXP "d"
ORDER BY LENGTH(word) DESC
LIMIT 1;
Obviously, you must generate one word REGEXP "a" condition per letter in your PHP code when constructing the query.
The query should then give you exactly one result, namely the longest word in the database containing all of the characters.
I solved problem with this function, full working code updated in question post
function remove($allowedCharacters, $value)
{
$newDict = $allowedCharacters;
if(($key = array_search($value, $newDict)))
{
unset($newDict[$key]);
}
return $newDict;
}
removed old one:
function remove($allowedCharacters, $value)
{
$newDict = [count($allowedCharacters) - 1];
$index = 0;
foreach($allowedCharacters as $x)
{
if($x != $value)
{
$newDict[$index++] = $x;
}
else
{
//we removed the first hit, now copy the rest
break;
}
}
//System.arraycopy(allowedCharacters, index + 1, newDict, index, allowedCharacters.length - (index + 1)); JAVA arraycopy(Object src, int srcPos, Object dest, int destPos, int length)
//$newDict[$index] = array_splice($allowedCharacters, $index +1, count($allowedCharacters) - ($index +1));
//$newDict = $allowedCharacters;
return $newDict;
}
I'm using a clustered redis. All I want to do is adding a new value to a limited set.
This is my code:
$redis->watch(keyMem)
$count = $redis->scard($keyMem);
if($count < $limit)
$redis->multi()
->sadd($keyMem, $value)
->exec();
and I get:
"cannot use 'watch' over clusters of connections."
I couldn't find any solution and i coded my own lock.
$keyLock = $keyMem."lock";
$start_time = microtime();
while(true){
if($redis->setnx($keyLock, "1")){
$count = $redis->scard($keyMem);
if(i$count < $limit){
$r = $tredis->sadd($keyMem, $value);
}
$redis->del($keyLock);
}
else{
if(microtime() - $start_time > 0.05){
$tredis->del($keyLock);
}
}
}
I am stuck in resolving a PHP script.
I want to calculate a result from a set of instructions. Instructions comprise of a keyword and a number that are separated by a space per line. Instructions are loaded from file and results are output to the screen. Any number of Instructions can be specified. Instructions are operators (add, divide, subtract, multiply). The instructions will ignore mathematical precedence. The last instruction should be “apply” and a number (e.g., “apply 3”). The calculator is then initialised with that number and the previous instructions are applied to that number.
[Input]
add 2
multiply 3
apply 3
[Output]
15
this is what i have tried but i cant get the logic to complete the methods
class Calculator {
public $result = 0;
public $queue = Array();
public parseString($text) {
// parse input string
$cmds = explode(" ", $text);
foreach($cmds as $cmd) {
$cmd = trim($cmd);
if(!$cmd) continue; // blank or space, ignoring
$this->queue[] = $cmd;
}
// lets process commands
$command = false;
foreach($this->queue as $index => $cmd) {
if(is_number($cmd)) {
// if it's number fire previous command if exists
if(!$command || !method_exists($this, $command)) {
throw new Exception("Unknown command $command");
}
$this->$command($index, $cmd);
}else{
$command = $cmd;
}
}
}
public function apply($index, $number) {
// manipulate $result, $queue, $number
}
public function add($index, $number) {
// manipulate $result, $queue, $number
}
public function substract($index, $number) {
// manipulate $result, $queue, $number
}
}
$calculator = new Calculator();
$calculator->parseString('...');
how can i call or switch the add,divide,multiply,substract and how to distinguish and trigger apply word
any kind of help will be appreciated.
You should process the apply first and then cut it out of your queue array. Before you start looping through with the commands, simply test for the apply command and run it first. This simplifies the whole process.
After many minutes of experimentation and chatting, has been resolved.
<?php
error_reporting(E_ALL);
class Calculator {
public $result = 0;
public $queue = array();
public function parseString($text) {
// parse input string
$split = explode(" ", $text); //This gets your input into new lines
for ($i = 0; $i < count($split); $i += 2) $pairs[] = array($split[$i], $split[$i+1]);
foreach ($pairs as $bits) {
if ($bits[0] == "apply") {
$this->apply($bits[1]); //Set result equal to apply.
$this->queue[] = "output";
} else {
$this->queue[] = $bits; //Set the queue item as an array of (command, value).
}
}
//var_dump($this->queue);
//die;
// lets process commands
foreach ($this->queue as $index => $cmd) {
if ($cmd == "output") {
echo "Answer: " .$this->result;
return;
} else {
switch($cmd[0]) {
case "add":
$this->add($cmd[1]);
break;
case "subtract":
$this->subtract($cmd[1]);
break;
case "multiply":
$this->multiply($cmd[1]);
break;
case "divide":
$this->divide($cmd[1]);
break;
default:
echo "Unknown command!";
break;
}
}
}
}
public function apply($number) {
// manipulate $result, $queue, $number
$this->result = $number;
}
public function add($number) {
// manipulate $result, $queue, $number
$this->result += $number;
}
public function subtract($number) {
// manipulate $result, $queue, $number
$this->result -= $number;
}
public function multiply($number) {
// manipulate $result, $queue, $number
$this->result *= $number;
}
public function divide($number) {
// manipulate $result, $queue, $number
$this->result /= $number;
}
}
?>
Try using the array_shift and array_pop functions:
//pop the apply num off end off the queue
$result= array_pop($this->queue);
//now pop the apply operator off end of the queue
$operator = array_pop($this->queue);
//now get the first operator and numbers using array_shift
$operator = array_shift($this->queue); //get first operator
$num = array_shift($this->queue); //get first number
//loop perform operation on result using number till done.
while($num !== null)
{
$result = $operator($result, $num);
$operator = array_shift($this->queue);
$num = array_shift($this->queue);
}
I'm trying to program my own Sine function implementation for fun but I keep getting :
Fatal error: Maximum execution time of 30 seconds exceeded
I have a small HTML form where you can enter the "x" value of Sin(x) your looking for and the number of "iterations" you want to calculate (precision of your value), the rest is PhP.
The maths are based of the "Series definition" of Sine on Wikipedia :
--> http://en.wikipedia.org/wiki/Sine#Series_definition
Here's my code :
<?php
function factorial($int) {
if($int<2)return 1;
for($f=2;$int-1>1;$f*=$int--);
return $f;
};
if(isset($_POST["x"]) && isset($_POST["iterations"])) {
$x = $_POST["x"];
$iterations = $_POST["iterations"];
}
else {
$error = "You forgot to enter the 'x' or the number of iterations you want.";
global $error;
}
if(isset($x) && is_numeric($x) && isset($iterations) && is_numeric($iterations)) {
$x = floatval($x);
$iterations = floatval($iterations);
for($i = 0; $i <= ($iterations-1); $i++) {
if($i%2 == 0) {
$operator = 1;
global $operator;
}
else {
$operator = -1;
global $operator;
}
}
for($k = 1; $k <= (($iterations-(1/2))*2); $k+2) {
$k = $k;
global $k;
}
function sinus($x, $iterations) {
if($x == 0 OR ($x%180) == 0) {
return 0;
}
else {
while($iterations != 0) {
$result = $result+(((pow($x, $k))/(factorial($k)))*$operator);
$iterations = $iterations-1;
return $result;
}
}
}
$result = sinus($x, $iterations);
global $result;
}
else if(!isset($x) OR !isset($iterations)) {
$error = "You forgot to enter the 'x' or the number of iterations you want.";
global $error;
}
else if(isset($x) && !is_numeric($x)&& isset($iterations) && is_numeric($iterations)) {
$error = "Not a valid number.";
global $error;
}
?>
My mistake probably comes from an infinite loop at this line :
$result = $result+(((pow($x, $k))/(factorial($k)))*$operator);
but I don't know how to solve the problem.
What I'm tring to do at this line is to calculate :
((pow($x, $k)) / (factorial($k)) + (((pow($x, $k))/(factorial($k)) * ($operator)
iterating :
+ (((pow($x, $k))/(factorial($k)) * $operator)
an "$iterations" amount of times with "$i"'s and "$k"'s values changing accordingly.
I'm really stuck here ! A bit of help would be needed. Thank you in advance !
Btw : The factorial function is not mine. I found it in a PhP.net comment and apparently it's the optimal factorial function.
Why are you computing the 'operator' and power 'k' out side the sinus function.
sin expansion looks like = x - x^2/2! + x^3/3! ....
something like this.
Also remember iteration is integer so apply intval on it and not floatval.
Also study in net how to use global. Anyway you do not need global because your 'operator' and power 'k' computation will be within sinus function.
Best of luck.
That factorial function is hardly optimal—for speed, though it is not bad. At least it does not recurse. It is simple and correct though. The major aspect of the timeout is that you are calling it a lot. One technique for improving its performance is to remember, in a local array, the values for factorial previously computed. Or just compute them all once.
There are many bits of your code which could endure improvement:
This statement:
while($iterations != 0)
What if $iterations is entered as 0.1? Or negative. That would cause an infinite loop. You can make the program more resistant to bad input with
while ($iterations > 0)
The formula for computing a sine uses the odd numbers: 1, 3, 5, 7; not every integer
There are easier ways to compute the alternating sign.
Excess complication of arithmetic expressions.
return $result is within the loop, terminating it early.
Here is a tested, working program which has adjustments for all these issues:
<?php
// precompute the factorial values
global $factorials;
$factorials = array();
foreach (range (0, 170) as $j)
if ($j < 2)
$factorials [$j] = 1;
else $factorials [$j] = $factorials [$j-1] * $j;
function sinus($x, $iterations)
{
global $factorials;
$sign = 1;
for ($j = 1, $result = 0; $j < $iterations * 2; $j += 2)
{
$result += pow($x, $j) / $factorials[$j] * $sign;
$sign = - $sign;
}
return $result;
}
// test program to prove functionality
$pi = 3.14159265358979323846264338327950288419716939937510582097494459230781640628620;
$x_vals = array (0, $pi/4, $pi/2, $pi, $pi * 3/2, 2 * $pi);
foreach ($x_vals as $x)
{
$y = sinus ($x, 20);
echo "sinus($x) = $y\n";
}
?>
Output:
sinus(0) = 0
sinus(0.78539816339745) = 0.70710678118655
sinus(1.5707963267949) = 1
sinus(3.1415926535898) = 3.4586691443274E-16
sinus(4.7123889803847) = -1
sinus(6.2831853071796) = 8.9457384260403E-15
By the way, this executes very quickly: 32 milliseconds for this output.