Given a string that may contain any character (including a unicode characters), how can I convert this string into hexadecimal representation, and then reverse and obtain from hexadecimal this string?
Use pack() and unpack():
function hex2str( $hex ) {
return pack('H*', $hex);
}
function str2hex( $str ) {
return array_shift( unpack('H*', $str) );
}
$txt = 'This is test';
$hex = str2hex( $txt );
$str = hex2str( $hex );
echo "{$txt} => {$hex} => {$str}\n";
would produce
This is test => 546869732069732074657374 => This is test
Use a function like this:
<?php
function bin2hex($str) {
$hex = "";
$i = 0;
do {
$hex .= dechex(ord($str{$i}));
$i++;
} while ($i < strlen($str));
return $hex;
}
// Look what happens when ord($str{$i}) is 0...15
// you get a single digit hexadecimal value 0...F
// bin2hex($str) could return something like 4a3,
// decimals(74, 3), whatever the binary value is of those.
function hex2bin($str) {
$bin = "";
$i = 0;
do {
$bin .= chr(hexdec($str{$i}.$str{($i + 1)}));
$i += 2;
} while ($i < strlen($str));
return $bin;
}
// hex2bin("4a3") just broke. Now what?
// Using sprintf() to get it right.
function bin2hex($str) {
$hex = "";
$i = 0;
do {
$hex .= sprintf("%02x", ord($str{$i}));
$i++;
} while ($i < strlen($str));
return $hex;
}
// now using whatever the binary value of decimals(74, 3)
// and this bin2hex() you get a hexadecimal value you can
// then run the hex2bin function on. 4a03 instead of 4a3.
?>
Source: http://php.net/manual/en/function.bin2hex.php
Any reason why this code sometimes only generates 4 character strings?
function genID()
{
$id = '';
$values = '0123456789abcdefghijklmnopqrstuvwxyz';
for($i=0; $i < 5; $i++) :
$str = substr($values, rand(0, strlen($values)), 1);
if(!is_nan(acos($str)))
(mt_rand(0, 1)) ? $str = strtoupper($str) : '';
$id .= $str;
endfor;
return $id; // e.g: ifR8j
}
acos($str) accepts numbers not string.... if u remove the aphabets from the string
ie.
$values = '0123456789abcdefghijklmnopqrstuvwxyz';
to
$values = '0123456789';
you will get the length as 5... Hope this helps..
Try, something simple:
function genID() {
$id = '';
$i = $length = 4;
$possible = "0123456789bcdfghjkmnpqrstvwxyz";
$possibleChar = strlen($possible) - 1;
while ($i) {
$char = $possible[mt_rand(0, $possibleChar)];
while (!strstr($id, $char)) {
$id .= $char;
$i--;
}
}
return $id;
}
(mt_rand(0, 1)) ? $str = strtoupper($str) : '';
This condition is met so sometimes you get an empty char.
Fix the condition or do the loop in some other manner.
For example
while(strlen($id)<5) {
//do the loop
}
The loop iterates 5 times.
rand will also return strlen, so $str will sometimes be ""
$str = substr($values, rand(0, strlen($values))-1, 1);
This will generate 5 characters always.
I need to scramble/encode all e-mail addresses in a string, turn them into links and leave the rest of the string intact?
I'm using
$withlinks = preg_replace("/([\w-?&;#~=\.\/]+\#(\[?)[a-zA-Z0-9\-\.]+\.([a-zA-Z]{2,3}|[0-9]{1,3})(\]?))/i","$1",$nolinks);
to make links out of e-mails and
function encode_email($str) {
$str = mb_convert_encoding($str , 'UTF-32', 'UTF-8'); //big endian
$split = str_split($str, 4);
$res = "";
foreach ($split as $c) {
$cur = 0;
for ($i = 0; $i < 4; $i++) {
$cur |= ord($c[$i]) << (8*(3 - $i));
}
$res .= "&#" . $cur . ";";
}
return $res;
}
to encode the addresses but I can't figure out how to put them together, so that only e-mails would be encoded and turned into links.
You can use preg_replace_callback so that you can manipulate the replacement text to be exactly what you want...
<?php
// test string
$nolinks = "amy#winehous.com is an email for bobby#fisher.com plays chess";
// your original function
function encode_email($str)
{
$str = mb_convert_encoding($str, 'UTF-32', 'UTF-8'); //big endian
$split = str_split($str, 4);
$res = "";
foreach ($split as $c) {
$cur = 0;
for ($i = 0; $i < 4; $i++) {
$cur |= ord($c[$i]) << (8 * (3 - $i));
}
$res .= "&#" . $cur . ";";
}
return $res;
}
// function used for callback
function encode_email_and_add_link($in)
{
// get encoded email address (don't actually know what this function does)
$encoded = encode_email($in[1]);
// return a hyperlink string built with encoded email address
return "$encoded";
}
// do the regex with callback
$withlinks = preg_replace_callback("/([\w-?&;#~=\.\/]+\#(\[?)[a-zA-Z0-9\-\.]+\.([a-zA-Z]{2,3}|[0-9]{1,3})(\]?))/i", 'encode_email_and_add_link', $nolinks);
// output the results
echo $withlinks;
I want to generate a random number in PHP where the digits itself should not repeat in that number.
Is that possible?
Can you paste sample code here?
Ex: 674930, 145289. [i.e Same digit shouldn't come]
Thanks
Here is a good way of doing it:
$amountOfDigits = 6;
$numbers = range(0,9);
shuffle($numbers);
for($i = 0;$i < $amountOfDigits;$i++)
$digits .= $numbers[$i];
echo $digits; //prints 217356
If you wanted it in a neat function you could create something like this:
function randomDigits($length){
$numbers = range(0,9);
shuffle($numbers);
for($i = 0;$i < $length;$i++)
$digits .= $numbers[$i];
return $digits;
}
function randomize($len = false)
{
$ints = array();
$len = $len ? $len : rand(2,9);
if($len > 9)
{
trigger_error('Maximum length should not exceed 9');
return 0;
}
while(true)
{
$current = rand(0,9);
if(!in_array($current,$ints))
{
$ints[] = $current;
}
if(count($ints) == $len)
{
return implode($ints);
}
}
}
echo randomize(); //Numbers that are all unique with a random length.
echo randomize(7); //Numbers that are all unique with a length of 7
Something along those lines should do it
<?php
function genRandomString() {
$length = 10; // set length of string
$characters = '0123456789'; // for undefined string
$string ="";
for ($p = 0; $p < $length; $p++) {
$string .= $characters[mt_rand(0, strlen($characters))];
}
return $string;
}
$s = genRandomString(); //this is your random print var
or
function rand_string( $length )
{
$chars = "0123456789";
$size = strlen( $chars );
for( $i = 0; $i < $length; $i++ )
{
$str .= $chars[ rand( 0, $size – 1 ) ];
}
return $str;
}
$rid= rand_string( 6 ); // 6 means length of generate string
?>
$result= "";
$numbers= "0123456789";
$length = 8;
$i = 0;
while ($i < $length)
{
$char = substr($numbers, mt_rand(0, strlen($numbers)-1), 1);
//prevents duplicates
if (!strstr($result, $char))
{
$result .= $char;
$i++;
}
}
This should do the trick. In $numbers you can put any char you want, for example: I have used this to generate random passwords, productcodes etc.
The least amount of code I saw for something like this was:
function random_num($n=5)
{
return rand(0, pow(10, $n));
}
But I'm assuming it requires more processing to do this than these other methods.
How can I generate a (pseudo)random alpha-numeric string, something like: 'd79jd8c' in PHP?
First make a string with all your possible characters:
$characters = 'abcdefghijklmnopqrstuvwxyz0123456789';
You could also use range() to do this more quickly.
Then, in a loop, choose a random number and use it as the index to the $characters string to get a random character, and append it to your string:
$string = '';
$max = strlen($characters) - 1;
for ($i = 0; $i < $random_string_length; $i++) {
$string .= $characters[mt_rand(0, $max)];
}
$random_string_length is the length of the random string.
I like this function for the job
function randomKey($length) {
$pool = array_merge(range(0,9), range('a', 'z'),range('A', 'Z'));
for($i=0; $i < $length; $i++) {
$key .= $pool[mt_rand(0, count($pool) - 1)];
}
return $key;
}
echo randomKey(20);
Generate cryptographically strong, random (potentially) 8-character string using the openssl_random_pseudo_bytes function:
echo bin2hex(openssl_random_pseudo_bytes(4));
Procedural way:
function randomString(int $length): string
{
return bin2hex(openssl_random_pseudo_bytes($length));
}
Update:
PHP7 introduced the random_x() functions which should be even better. If you come from PHP 5.X, use excellent paragonie/random_compat library which is a polyfill for random_bytes() and random_int() from PHP 7.
function randomString($length)
{
return bin2hex(random_bytes($length));
}
One line solution:
echo substr( str_shuffle( str_repeat( 'abcdefghijklmnopqrstuvwxyz0123456789', 10 ) ), 0, 7 );
You can change the substr parameter in order to set a different length for your string.
Use the ASCII table to pick a range of letters, where the: $range_start , $range_end is a value from the decimal column in the ASCII table.
I find that this method is nicer compared to the method described where the range of characters is specifically defined within another string.
// range is numbers (48) through capital and lower case letters (122)
$range_start = 48;
$range_end = 122;
$random_string = "";
$random_string_length = 10;
for ($i = 0; $i < $random_string_length; $i++) {
$ascii_no = round( mt_rand( $range_start , $range_end ) ); // generates a number within the range
// finds the character represented by $ascii_no and adds it to the random string
// study **chr** function for a better understanding
$random_string .= chr( $ascii_no );
}
echo $random_string;
See More:
chr function
mt_rand function
I know it's an old post but I'd like to contribute with a class I've created based on Jeremy Ruten's answer and improved with suggestions in comments:
class RandomString
{
private static $characters = 'abcdefghijklmnopqrstuvwxyz0123456789';
private static $string;
private static $length = 8; //default random string length
public static function generate($length = null)
{
if($length){
self::$length = $length;
}
$characters_length = strlen(self::$characters) - 1;
for ($i = 0; $i < self::$length; $i++) {
self::$string .= self::$characters[mt_rand(0, $characters_length)];
}
return self::$string;
}
}
Simple guys .... but remember each byte is random between 0 and 255 which for a random string will be fine. Also remember you'll have two characters to represent each byte.
$str = bin2hex(random_bytes(32)); // 64 character string returned
Maybe I missed something here, but here's a way using the uniqid() function.
I have made the following quick function just to play around with the range() function. It just might help someone sometime.
Function pseudostring($length = 50) {
// Generate arrays with characters and numbers
$lowerAlpha = range('a', 'z');
$upperAlpha = range('A', 'Z');
$numeric = range('0', '9');
// Merge the arrays
$workArray = array_merge($numeric, array_merge($lowerAlpha, $upperAlpha));
$returnString = "";
// Add random characters from the created array to a string
for ($i = 0; $i < $length; $i++) {
$character = $workArray[rand(0, 61)];
$returnString .= $character;
}
return $returnString;
}
You can use the following code. It is similar to existing functions except that you can force special character count:
function random_string() {
// 8 characters: 7 lower-case alphabets and 1 digit
$character_sets = [
["count" => 7, "characters" => "abcdefghijklmnopqrstuvwxyz"],
["count" => 1, "characters" => "0123456789"]
];
$temp_array = array();
foreach ($character_sets as $character_set) {
for ($i = 0; $i < $character_set["count"]; $i++) {
$random = random_int(0, strlen($character_set["characters"]) - 1);
$temp_array[] = $character_set["characters"][$random];
}
}
shuffle($temp_array);
return implode("", $temp_array);
}
function generateRandomString($length = 10) {
$characters = '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ';
$charactersLength = strlen($characters);
$randomString = '';
for ($i = 0; $i < $length; $i++) {
$randomString .= $characters[rand(0, $charactersLength - 1)];
}
return $randomString;
}
echo generateRandomString();
If you want a very easy way to do this, you can lean on existing PHP functions. This is the code I use:
substr( sha1( time() ), 0, 15 )
time() gives you the current time in seconds since epoch, sha1() encrypts it to a string of 0-9a-f, and substr() lets you choose a length. You don't have to start at character 0, and whatever the difference is between the two numbers will be the length of the string.
First list the desired characters
$chars = '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ';
Use the str_shuffle($string) function. This function will provide you a randomly shuffled string.
$alpha=substr(str_shuffle($chars), 0, 50);
50 is the Length of string.
This is something I use:
$cryptoStrong = true; // can be false
$length = 16; // Any length you want
$bytes = openssl_random_pseudo_bytes($length, $cryptoStrong);
$randomString = bin2hex($bytes);
You can see the Docs for openssl_random_pseudo_bytes here, and the Docs for bin2hex here
Jeremy's answer is great. If, like me, you're unsure of how to implement range(), you can see my version using range().
<?php
$character_array = array_merge(range('a', 'z'), range(0, 9));
$string = "";
for($i = 0; $i < 6; $i++) {
$string .= $character_array[rand(0, (count($character_array) - 1))];
}
echo $string;
?>
This does the exact same thing as Jeremy's but uses merged arrays where he uses a string, and uses count() where he uses strlen().
1 line:
$FROM = 0; $TO = 'zzzz';
$code = base_convert(rand( $FROM ,base_convert( $TO , 36,10)),10,36);
echo $code;
The modern way to do that with type hint / rand_int for real randomeness
function random_string(int $size): string
{
$characters = array_merge(
range(0, 9),
range('A', 'Z')
);
$string = '';
$max = count($characters) - 1;
for ($i = 0; $i < $size; $i++) {
$string .= $characters[random_int(0, $max)];
}
return $string;
}
public function randomString($length = 8)
{
$characters = implode([
'ABCDEFGHIJKLMNOPORRQSTUWVXYZ',
'abcdefghijklmnoprqstuwvxyz',
'0123456789',
//'!##$%^&*?'
]);
$charactersLength = strlen($characters) - 1;
$string = '';
while ($length) {
$string .= $characters[mt_rand(0, $charactersLength)];
--$length;
}
return $string;
}