Related
heres my code
while($x <= $num) {
$code = rand(1,666666).rand(2,88888888);
$INC = qry_run("Insert into ms_code2 (code) Values(".$code.")");
$x++;
}
the main problem is when this loop work sometimes it generate 14 number sometimes 10 and sometimes 12
I won't get into a discussion about how "random" we can ever really get, I am pretty sure this will generate a number random enough! :)
function randomNumber($length) {
$result = '';
for($i = 0; $i < $length; $i++) {
$result .= mt_rand(0, 9);
}
return $result;
}
..and of course then it's just echo randomNumber(14);
You can use this simple trick to generate (n) number of random numbers
function generateCode($limit){
$code = 0;
for($i = 0; $i < $limit; $i++) { $code .= mt_rand(0, 9); }
return $code;
}
echo generateCode(14);
This above function returns 14 random digits.
A simplest one could be this also, Here we are using array_map and range to iterate over callback function and maintain a string.
Try this code snippet here
<?php
ini_set('display_errors', 1);
$string="";
array_map(function($value) use(&$string){
$string.=mt_rand(0, 9);
}, range(0,13));
echo $string;
Some time ago during a job interview I got the task to reverse a string in PHP without using strrev.
My first solution was something like this:
$s = 'abcdefg';
$temp = '';
for ($i = 0, $length = mb_strlen($s); $i < $length; $i++) {
$temp .= $s{$length - $i - 1};
}
var_dump($temp);
// outputs string(7) "gfedcba"
then they asked me if I could do this without doubling the memory usage (not using the $temp variable or any variable to copy the reversed string to) and I failed.
This kept bugging me and since then I tried to solve this multiple times but I constantly failed.
My latest try looks like this:
$s = 'abcdefg';
for ($i = 0, $length = mb_strlen($s); $i < $length; $i++) {
$s = $s{$i * 2} . $s;
}
var_dump($s);
// outputs string(14) "gfedcbaabcdefg"
It's not a solution to chop off "abcdefg" after the loop because then I would still double the amount of memory used. I need to remove the last character in every iteration of the loop.
I tried to use mb_substr like this:
$s = 'abcdefg';
for ($i = 0, $length = mb_strlen($s); $i < $length; $i++) {
$s = $s{$i * 2} . mb_substr($s, $length - $i - 1, 1);
}
var_dump($s);
but it only gives me Uninitialized string offset errors.
This is where I'm stuck (again). I tried googling but all the solutions I found either echo the characters directly or use a temporary variable.
I also found the Question PHP String reversal without using extra memory but there's no answer that fits my needs.
That's an interesting one.
Here's something I just came up with:
$s = 'abcdefghijklm';
for($i=strlen($s)-1, $j=0; $j<$i; $i--, $j++) {
list($s[$j], $s[$i]) = array($s[$i], $s[$j]);
}
echo $s;
list() can be used to assign a list of variables in one operation. So what I am doing is simply swapping characters (starting with first and last, then second-first and second-last and so on, till it reaches the middle of the string)
Output is mlkjihgfedcba.
Not using any other variables than $s and the counters, so I hope that fits your criteria.
You can use the fact that in PHP a string can be thought of as an array of characters.
Then basically what you want to do is to replace each character $i on the left side of the middle of the string with the character $j on the right side of the middle with the same distance.
For example, in a string of seven characters the middle character is on position 3. The character on position 0 (distance 3) needs to be swapped with the character on position 6 (3 + 3), the character on position 1 (distance 2) needs to be swapped with the character on position 5 (3 + 2), etc.
This algorithm can be implemented as follows:
$s = 'abcdefg';
$length = strlen($s);
for ($i = 0, $j = $length-1; $i < ($length / 2); $i++, $j--) {
$t = $s[$i];
$s[$i] = $s[$j];
$s[$j] = $t;
}
var_dump($s);
$string = 'abc';
$reverted = implode(array_reverse(str_split($string)));
You could use the XOR swap trick.
function rev($str) {
$len = strlen($str);
for($i = 0; $i < floor($len / 2); ++$i) {
$str[$i] = $str[$i] ^ $str[$len - $i - 1];
$str[$len - $i - 1] = $str[$i] ^ $str[$len - $i - 1];
$str[$i] = $str[$i] ^ $str[$len - $i - 1];
}
return $str;
}
print rev("example");
Try this:
$s = 'abcdefg';
for ($i = strlen($s)-1; $i>=0; $i--) {
$s .= $s[$i];
$s[$i] = NULL;
}
var_dump(trim($s));
Here it is PHP7 version of this:
echo "\u{202E}abcdefg"; // outs: gfedcba
PHP strings are kinda-sorta mutable, but due to copy-on-write it's very difficult to modify them in-place without a copy being made. Some of the above solutions work, but only because they're stand-alone; some already fail because they define a function without a pass-by-reference argument. To get the code to actually operate in-place in a larger program, you'd need to pay careful attention to assignments, function arguments, and scopes.
Example:
$string1 = 'abc';
$string2 = $string1;
$string1[0] = 'b';
print("$string1, $string2");
> "abc, bbc"
I suppose that if between initializing the variable and modifying it you only ever used by-reference assignments (&=) and reference arguments (function rev(&$string)) (or assign the string to an object property initially, and then never assign it to any other variable), you might be able to change the original value of the string without making any copies. That's a bit ridiculous, however, and I'd assume that the interviewer who came up with that question didn't know about copy-on-write.
This isn't quite the same as immutability in other languages, by the way, because it applies to arrays too:
$a = [0, 1, 2];
$b = $a;
$b[0] = 1;
print(implode($a).implode($b));
> "012112"
To sum up, all types (except for objects as of PHP5) are assigned with copy-on-write unless you specifically use the &= operator. The assignment doesn't copy them, but unlike most other languages (C, Java, Python...) that either change the original value (arrays) or don't allow write access at all (strings), PHP will silently create a copy before making any changes.
Of course, if you switched to a language with more conventional pointers and also switched to byte arrays instead of strings, you could use XOR to swap each pair of characters in place:
for i = 0 ... string.length / 2:
string[i] ^= string[string.length-1-i]
string[string.length-1-i] ^= string[i]
string[i] ^= string[string.length-1-i]
Basically #EricBouwers answer, but you can remove the 2nd placeholder variable $j
function strrev2($str)
{
$len = strlen($str);
for($i=0;$i<$len/2;$i++)
{
$tmp = $str[$i];
$str[$i] = $str[$len-$i-1];
$str[$len-$i-1] = $tmp;
}
return $str;
}
Test for the output:
echo strrev2("Hi there!"); // "!ereht iH"
echo PHP_EOL;
echo strrev2("Hello World!"); // "!dlroW olleH"
This will go through the list and stop halfway, it swaps the leftmost and rightmost, and works it's way inward, and stops at the middle. If odd numbered, the pivot digit is never swapped with itself, and if even, it swaps the middle two and stops. The only extra memory used is $len for convenience and $tmp for swapping.
If you want a function that doesn't return a new copy of the string, but just edits the old one in place you can use the following:
function strrev3(&$str)
{
$len = strlen($str);
for($i=0;$i<$len/2;$i++)
{
$tmp = $str[$i];
$str[$i] = $str[$len-$i-1];
$str[$len-$i-1] = $tmp;
}
}
$x = "Test String";
echo $x; // "Test String"
strrev3($x);
echo PHP_EOL;
echo $x; // "gnirtS tseT"
Using &$str passes a direct pointer the the string for editing in place.
And for a simpler implementation like #treegardens, you can rewrite as:
$s = 'abcdefghijklm';
$len = strlen($s);
for($i=0; $i < $len/2; $i++) {
list($s[$i], $s[$len-$i-1]) = array($s[$len-$i-1], $s[$i]);
}
echo $s;
It has the similar logic, but I simplified the for-loop quite a bit.
Its Too Simple
//Reverse a String
$string = 'Basant Kumar';
$length = strlen($string);
for($i=$length-1;$i >=0;$i--){
echo $string[$i];
}
Here is my code to solve your problem
<?php
$s = 'abcdefg';
for ($i = 0, $length = mb_strlen($s); $i < $length; $i++) {
$s = $s{$i}.mb_substr($s,0,$i).mb_substr($s,$i+1);
}
var_dump($s);
?>
You could also use a recursion to reverse the string. Something like this for example:
function reverse($s) {
if(strlen($s) === 1) return $s;
return substr($s, strlen($s)-1) . reverse(substr($s , 0, strlen($s)-1));
}
What you do here is actually returning the last character of the string and then calling again the same function with the substring that contains the initial string without the last character. When you reach the point when your string is just one character then you end the recursion.
You can use this code to reverse a string without using the reserved function in php.
Code:
<?php
function str_rev($y)// function for reversing a string by passing parameters
{
for ($x = strlen($y)-1; $x>=0; $x--) {
$y .= $y[$x];
$y[$x] = NULL;
}
echo $y;
}
str_rev("I am a student");
?>
Output:
tneduts a ma I
In the above code, we have passed the value of the string as the parameter.We have performed the string reversal using for loop.
you could use substr with negative start.
Theory & Explanation
you can start with for loop with counter from 1 to length of string, and call substr inside iteration with counter * -1 (which will convert the counter into negative value) and length of 1.
So for the first time counter would be 1 and by multiplying with -1 will turn it to -1
Hence substr('abcdefg', -1, 1); will get you g
and next iteration substr('abcdefg', -2, 1); will get you f
and substr('abcdefg', -3, 1); will get you e
and so on ...
Code
$str = 'abcdefghijklmnopqrstuvwxyz';
for($i=1; $i <= strlen($str); $i++) {
echo substr($str, $i*-1, 1);
}
In Action: https://eval.in/583208
public function checkString($str){
if(!empty($str)){
$i = 0;
$str_reverse = '';
while(isset($str[$i])){
$strArr[] = $str[$i];
$i++;
}
for($j = count($strArr); $j>= 0; $j--){
if(isset($strArr[$j])){
$str_reverse .= $strArr[$j];
}
}
if($str == $str_reverse){
echo 'It is a correct string';
}else{
echo 'Invalid string';
}
}
else{
echo 'string not found.';
}
}
//Reverse String word by word
$str = "Reverse string word by word";
$i = 0;
while ($d = $str[$i]) {
if($d == " ") {
$out = " ".$temp.$out;
$temp = "";
}
else
$temp .= $d;
$i++;
}
echo $temp.$out;
The following solution is very simple, but it does the job:
$string = 'Andreas';
$reversedString = '';
for($i = mb_strlen($string) - 1; $i >= 0; $i--){
$reversedString .= $string[$i];
}
var_dump($reversedString) then results: string(7) "saerdnA"
<?php
$value = 'abcdefg';
$length_value = strlen($value);
for($i = $length_value-1; $i >=0 ;$i--){
echo $value[$i];
}
?>
you can try this..
$string = "NASEEM";
$total_word = strlen($string);
for($i=0; $i<=$total_word; $i++)
{
echo substr($string,$total_word-$i,1);
}
i have used some built in function but without str_rev function .
<?php
$text = "red";
$arr = str_split($text);
$rev_text = array_reverse($arr);
echo join(" ",$rev_text);
?>
Try This
<?php
$str="abcde";
for($i=strlen($str)-1;$i>=0;$i--){
echo $str[$i];
}
?>
output
edcba
This is my solution to solve this.
$in = 'This is a test text';
$out = '';
// find string length
$len = strlen($in);
// loop through it and print it reverse
for ( $i = $len - 1; $i >=0;$i-- )
{
$out = $out.$in[$i];
}
echo $out;
Reverse string using recursion function.
$reverseString = '';
function Reverse($str, $len)
{
if ($len == 0) {
return $GLOBALS['reverseString'];
} else {
$len--;
$GLOBALS['reverseString'] .= $str[$len];
return Reverse($str, $len);
}
}
$str = 'Demo text';
$len = strlen($str);
echo Reverse($str, $len)
Try this
$warn = 'this is a test';
$i=0;
while(#$warn[$i]){
$i++;}
while($i>0)
{
echo $warn[$i-1]; $i--;
}
I want to create exact 5 random characters string with least possibility of getting duplicated. What would be the best way to do it? Thanks.
$rand = substr(md5(microtime()),rand(0,26),5);
Would be my best guess--Unless you're looking for special characters, too:
$seed = str_split('abcdefghijklmnopqrstuvwxyz'
.'ABCDEFGHIJKLMNOPQRSTUVWXYZ'
.'0123456789!##$%^&*()'); // and any other characters
shuffle($seed); // probably optional since array_is randomized; this may be redundant
$rand = '';
foreach (array_rand($seed, 5) as $k) $rand .= $seed[$k];
Example
And, for one based on the clock (fewer collisions since it's incremental):
function incrementalHash($len = 5){
$charset = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
$base = strlen($charset);
$result = '';
$now = explode(' ', microtime())[1];
while ($now >= $base){
$i = $now % $base;
$result = $charset[$i] . $result;
$now /= $base;
}
return substr($result, -5);
}
Note: incremental means easier to guess; If you're using this as a salt or a verification token, don't. A salt (now) of "WCWyb" means 5 seconds from now it's "WCWyg")
If for loops are on short supply, here's what I like to use:
$s = substr(str_shuffle(str_repeat("0123456789abcdefghijklmnopqrstuvwxyz", 5)), 0, 5);
You can try it simply like this:
$length = 5;
$randomletter = substr(str_shuffle("abcdefghijklmnopqrstuvwxyz"), 0, $length);
more details: http://forum.arnlweb.com/viewtopic.php?f=7&t=25
A speedy way is to use the most volatile characters of the uniqid function.
For example:
$rand = substr(uniqid('', true), -5);
The following should provide the least chance of duplication (you might want to replace mt_rand() with a better random number source e.g. from /dev/*random or from GUIDs):
<?php
$characters = '0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz';
$result = '';
for ($i = 0; $i < 5; $i++)
$result .= $characters[mt_rand(0, 61)];
?>
EDIT:
If you are concerned about security, really, do not use rand() or mt_rand(), and verify that your random data device is actually a device generating random data, not a regular file or something predictable like /dev/zero. mt_rand() considered harmful:
https://spideroak.com/blog/20121205114003-exploit-information-leaks-in-random-numbers-from-python-ruby-and-php
EDIT:
If you have OpenSSL support in PHP, you could use openssl_random_pseudo_bytes():
<?php
$length = 5;
$randomBytes = openssl_random_pseudo_bytes($length);
$characters = '0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz';
$charactersLength = strlen($characters);
$result = '';
for ($i = 0; $i < $length; $i++)
$result .= $characters[ord($randomBytes[$i]) % $charactersLength];
?>
I always use the same function for this, usually to generate passwords. It's easy to use and useful.
function randPass($length, $strength=8) {
$vowels = 'aeuy';
$consonants = 'bdghjmnpqrstvz';
if ($strength >= 1) {
$consonants .= 'BDGHJLMNPQRSTVWXZ';
}
if ($strength >= 2) {
$vowels .= "AEUY";
}
if ($strength >= 4) {
$consonants .= '23456789';
}
if ($strength >= 8) {
$consonants .= '##$%';
}
$password = '';
$alt = time() % 2;
for ($i = 0; $i < $length; $i++) {
if ($alt == 1) {
$password .= $consonants[(rand() % strlen($consonants))];
$alt = 0;
} else {
$password .= $vowels[(rand() % strlen($vowels))];
$alt = 1;
}
}
return $password;
}
It seems like str_shuffle would be a good use for this.
Seed the shuffle with whichever characters you want.
$my_rand_strng = substr(str_shuffle("ABCDEFGHIJKLMNOPQRSTUVWXYZ"), -5);
I also did not know how to do this until I thought of using PHP array's. And I am pretty sure this is the simplest way of generating a random string or number with array's. The code:
function randstr ($len=10, $abc="aAbBcCdDeEfFgGhHiIjJkKlLmMnNoOpPqQrRsStTuUvVwWxXyYzZ0123456789") {
$letters = str_split($abc);
$str = "";
for ($i=0; $i<=$len; $i++) {
$str .= $letters[rand(0, count($letters)-1)];
};
return $str;
};
You can use this function like this
randstr(20) // returns a random 20 letter string
// Or like this
randstr(5, abc) // returns a random 5 letter string using the letters "abc"
$str = '';
$str_len = 8;
for($i = 0, $i < $str_len; $i++){
//97 is ascii code for 'a' and 122 is ascii code for z
$str .= chr(rand(97, 122));
}
return $str
Similar to Brad Christie's answer, but using sha1 alrorithm for characters 0-9a-zA-Z and prefixed with a random value :
$str = substr(sha1(mt_rand() . microtime()), mt_rand(0,35), 5);
But if you have set a defined (allowed) characters :
$validChars = array('0','1','2' /*...*/,'?','-','_','a','b','c' /*...*/);
$validCharsCount = count($validChars);
$str = '';
for ($i=0; $i<5; $i++) {
$str .= $validChars[rand(0,$validCharsCount - 1)];
}
** UPDATE **
As Archimedix pointed out, this will not guarantee to return a "least possibility of getting duplicated" as the number of combination is low for the given character range. You will either need to increase the number of characters, or allow extra (special) characters in the string. The first solution would be preferable, I think, in your case.
If it's fine that you'll get only letters A-F, then here's my solution:
str_pad(dechex(mt_rand(0, 0xFFFFF)), 5, '0', STR_PAD_LEFT);
I believe that using hash functions is an overkill for such a simple task as generating a sequence of random hexadecimal digits. dechex + mt_rand will do the same job, but without unnecessary cryptographic work. str_pad guarantees 5-character length of the output string (if the random number is less than 0x10000).
Duplicate probability depends on mt_rand's reliability. Mersenne Twister is known for high-quality randomness, so it should fit the task well.
works fine in PHP (php 5.4.4)
$seed = str_split('abcdefghijklmnopqrstuvwxyz');
$rand = array_rand($seed, 5);
$convert = array_map(function($n){
global $seed;
return $seed[$n];
},$rand);
$var = implode('',$convert);
echo $var;
Live Demo
Source: PHP Function that Generates Random Characters
This simple PHP function worked for me:
function cvf_ps_generate_random_code($length=10) {
$string = '';
// You can define your own characters here.
$characters = "23456789ABCDEFHJKLMNPRTVWXYZabcdefghijklmnopqrstuvwxyz";
for ($p = 0; $p < $length; $p++) {
$string .= $characters[mt_rand(0, strlen($characters)-1)];
}
return $string;
}
Usage:
echo cvf_ps_generate_random_code(5);
Here are my random 5 cents ...
$random=function($a, $b) {
return(
substr(str_shuffle(('\\`)/|#'.
password_hash(mt_rand(0,999999),
PASSWORD_DEFAULT).'!*^&~(')),
$a, $b)
);
};
echo($random(0,5));
PHP's new password_hash() (* >= PHP 5.5) function is doing the job for generation of decently long set of uppercase and lowercase characters and numbers.
Two concat. strings before and after password_hash within $random function are suitable for change.
Paramteres for $random() *($a,$b) are actually substr() parameters. :)
NOTE: this doesn't need to be a function, it can be normal variable as well .. as one nasty singleliner, like this:
$random=(substr(str_shuffle(('\\`)/|#'.password_hash(mt_rand(0,999999), PASSWORD_DEFAULT).'!*^&~(')), 0, 5));
echo($random);
function CaracteresAleatorios( $Tamanno, $Opciones) {
$Opciones = empty($Opciones) ? array(0, 1, 2) : $Opciones;
$Tamanno = empty($Tamanno) ? 16 : $Tamanno;
$Caracteres=array("0123456789","abcdefghijklmnopqrstuvwxyz","ABCDEFGHIJKLMNOPQRSTUVWXYZ");
$Caracteres= implode("",array_intersect_key($Caracteres, array_flip($Opciones)));
$CantidadCaracteres=strlen($Caracteres)-1;
$CaracteresAleatorios='';
for ($k = 0; $k < $Tamanno; $k++) {
$CaracteresAleatorios.=$Caracteres[rand(0, $CantidadCaracteres)];
}
return $CaracteresAleatorios;
}
I`ve aways use this:
<?php function fRand($len) {
$str = '';
$a = "abcdefghijklmnopqrstuvwxyz0123456789";
$b = str_split($a);
for ($i=1; $i <= $len ; $i++) {
$str .= $b[rand(0,strlen($a)-1)];
}
return $str;
} ?>
When you call it, sets the lenght of string.
<?php echo fRand([LENGHT]); ?>
You can also change the possible characters in the string $a.
Simple one liner which includes special characters:
echo implode("", array_map(function() {return chr(mt_rand(33,126));}, array_fill(0,5,null)));
Basically, it fills an array with length 5 with null values and replaces each value with a random symbol from the ascii-range and as the last, it joins them together t a string.
Use the 2nd array_fill parameter to control the length.
It uses the ASCII Table range of 33 to 126 which includes the following characters:
!"#$%&'()*+,-./0123456789:;<=>?#ABCDEFGHIJKLMNOPQRSTUVWXYZ[\]^_`abcdefghijklmnopqrstuvwxyz{|}~
I would like to know how can I add comma's to numbers. To make my question simple.
I would like to change this:
1210 views
To:
1,210 views
and :
14301
to
14,301
and so on for larger numbers. Is it possible with a php function?
from the php manual http://php.net/manual/en/function.number-format.php
I'm assuming you want the english format.
<?php
$number = 1234.56;
// english notation (default)
$english_format_number = number_format($number);
// 1,235
// French notation
$nombre_format_francais = number_format($number, 2, ',', ' ');
// 1 234,56
$number = 1234.5678;
// english notation with a decimal point and without thousands seperator
$english_format_number = number_format($number, 2, '.', '');
// 1234.57
?>
my 2 cents
The Following code is working for me, may be this is helpful to you.
$number = 1234.56;
echo number_format($number, 2, '.', ',');
//1,234.56
$number = 1234.56;
//Vietnam notation(comma for decimal point, dot for thousand separator)
$number_format_vietnam = number_format($number, 2, ',', '.');
//1.234,56
This is a bangladeshi format
First create a function
function numberFormat($number, $decimals=0)
{
// $number = 555;
// $decimals=0;
// $number = 555.000;
// $number = 555.123456;
if (strpos($number,'.')!=null)
{
$decimalNumbers = substr($number, strpos($number,'.'));
$decimalNumbers = substr($decimalNumbers, 1, $decimals);
}
else
{
$decimalNumbers = 0;
for ($i = 2; $i <=$decimals ; $i++)
{
$decimalNumbers = $decimalNumbers.'0';
}
}
// return $decimalNumbers;
$number = (int) $number;
// reverse
$number = strrev($number);
$n = '';
$stringlength = strlen($number);
for ($i = 0; $i < $stringlength; $i++)
{
if ($i%2==0 && $i!=$stringlength-1 && $i>1)
{
$n = $n.$number[$i].',';
}
else
{
$n = $n.$number[$i];
}
}
$number = $n;
// reverse
$number = strrev($number);
($decimals!=0)? $number=$number.'.'.$decimalNumbers : $number ;
return $number;
}
Call the function
* numberFormat(5000000, 2) // 50,00,000.00
* numberFormat(5000000) // 50,00,000
Often, if a number is big enough to have commas in it, you might want to do without any numbers after a decimal point - but if the value you are showing could ever be small, you would want to show those decimal places. Apply number_format conditionally, and you can use it to both add your commas and clip off any irrelevant post-point decimals.
if($measurement1 > 999) {
//Adds commas in thousands and drops anything after the decimal point
$measurement1 = number_format($measurement1);
}
Works well if you are showing a calculated value derived from a real world input.
Give it a try:
function format_my_number() {
$result = number_format(14301,2,',','.');
return $result;
}
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;
}