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The rand() function generates a random integer. Tip: If you want a random integer between 10 and (inclusive), use rand (10,). Tip: The mt_rand() function produces a better random value, and is 4 times faster than rand(). Syntax. Sep 24, · The rand () function is used in PHP to generate a random integer. The rand () PHP function can also be used to generate a random number within a specific range, such as a number between 10 and If no max limit is specified when using the rand () PHP function, the largest integer that can be returned is determined by the getrandmax () function, which varies by operating system.
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How would it be possible to generate a random, unique string using numbers and letters for use in a verify link? Like when you create an account on a website, and it sends you an email with a link, and you have to click that link in order to verify your account.
Security Notice : This solution should not be used in situations where the quality of your randomness can affect the security of an application. In particular, rand and uniqid are not cryptographically secure random number generators. See Scott's answer for a secure alternative. I was just looking into how to solve this same problem, but I also want my function to create a token that can be used for password retrieval as well.
This means that I need to limit the ability of the token to be guessed. Because uniqid is based on the time, and according to php. Unfortunately this only has an alphabet of [a-f]but it works. You can use custom alphabet how to clear general awareness for bank exams required.
Just pass a string with supported chars to the constructor or setter:. I'm late but I'm here with some good research data based on the functions provided by Scott's answer. So I set up a Digital Ocean droplet just for this 5-day long automated test and how to generate random number in php code the generated unique strings in a MySQL database. So we can say that if we use a length of 15 or above with Scott's functions, then we can generate highly reliable unique strings. Here is the table showing my research data:.
You can use UUID Universally Unique Identifierit can be used for any purpose, from user authentication string to payment transaction id. A UUID is a octet bit number. In its canonical form, a UUID is represented by 32 hexadecimal digits, displayed in five groups separated by hyphens, in the form for a total of 36 characters 32 alphanumeric characters and four hyphens. Use the code below to generate the random number of 11 characters or change the number as per your requirement.
This is a simple function that allows you to generate random strings containing Letters and Numbers alphanumeric. You can also limit the string length. However, note that you do not control the length of the string if you use base You can use bin2hex to do that, using 32 bytes will turn into a 64 char string. But it will only work like so in an EVEN string. This function returns timestamp based unique identifier as a string. I duplicate 10 times the array[,A-Z] and shuffle the elements, after I get a random start point for substr to be more 'creative' : you can add [a-z] and other elements to array, duplicate more or less, be more creative than me.
I like to use hash keys when dealing verification links. I would recommend using the microtime and hashing that using MD5 since there should be no reason why the keys should be the same since what are the symptoms of appendix hashes based off of the microtime.
If you want compare with another string to be sure that is a unique sequence you can use this trick A simple solution is to convert base 64 to alphanumeric by discarding the non-alphanumeric characters. Edit: I just revisited this because I need something a bit more flexible. Here is a solution that performs a bit better than the above and gives the option to specify any subset of the ASCII character set:.
I am also required to generate unique API token for my each user. Following is my approach, i used user information Userid and Username :. Please note that I multiplied the timestamp by three to create a confusion for whoever user might be wondering how this token is generated.
I believe the problem with all the existing ideas is that they are how to generate random number in php code unique, but not definitely unique as pointed out in Dariusz Walczak's reply to loletech. I have a solution that actually is unique. It requires that your script have some sort of memory. For me this is a SQL database. You could also simply write to a file somewhere. There are two implementations:. First method: have TWO fields rather than 1 that provide uniqueness.
The second field is not unique but is random. This can be generated with any of the other techniques people have already mentioned. Scott's idea was good, but md5 is convenient and probably good enough for most purposes:. Second method: Basically the same idea, but initially pick a maximum number of strings that will ever be generated. This could just be a really big number like a trillion. Then do the same thing, generate an ID, but zero pad it so that all IDs are the same number of digits.
Then just concatenate the ID with the random string. It will be random enough for most purposes, but the ID section will ensure that it is also unique. Stack Overflow for Teams — Collaborate and share knowledge with a private group. Create a free Team What is Teams? Learn more. PHP: How to generate a random, unique, alphanumeric string for use in a secret how to download movies to your xbox 360 free Ask Question.
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Viewed k times. Like when you create an account on a website, and it sends you an how to generate random number in php code with a link, and you have to click that link in how to generate random number in php code to verify your account How can I generate one of those using PHP?
Andrew Andrew k gold badges silver badges bronze badges. All you need are strings and uniformly distributed random numbers. Hey Andrew, you should choose Scott as the correct answer. Anyone reading this afterplease, please look here: paragonie. OpenSSL and uniqid are insecure.
Add a comment. Active Oldest Votes. Scott Arciszewski 30k 16 16 gold badges 84 84 silver badges bronze badges. Both methods do not guarantee uniqueness - length of the input of the md5 function is greater than length of its output and according to the en. On the what is the sea wolf about hand, the greater the population relying on hashes to achieve the "unique" id, the greater the probability of occurring at least one collision see en.
The probability may be tiny for most of solutions but it still exists. This is not a secure method of generating random values. See Scott's answer.
For email confirmations that expire relatively soon, I think the tiny possibility that one person might one day confirm someone else's email is a negligible risk. But you could always check if the token already exists in the DB after creating it and just pick a new one if that is the case. However, the time you spend writing that snippet of code is likely wasted as it will most likely never be run.
Do note that md5 returns hexadecimal values, meaning the character set is limited to  and [a-f]. Show 1 more comment. Below is the strongest function I could make that satisfies the criteria This is an implemented version of Erik's answer. Scott Scott Plaintext password storage is awful! I use blowfish. But after the token is generated it allows the holder of the token to reset the password, so the token is password equivalent while it is valid and is treated as such.
Hey, I combined your excellent code with the convenient Kohana Text::random method functionality and created this gist: gist. I tested it with 10 chars as length. I used this process and found it super slow. With a length of 36 it timed out on the dev server. With a length of 24 it still took what day of ovulation for a boy 30 seconds. Not sure what I did wrong but it was too slow for me and I opted for another solution.
Show 25 more comments. I'm sorry but how do I run this thing? Thank you. Just pass an integer to it to specify length of the resulting string. Thanks it works for me but Custom Alphabet didn't. I got empty output when I echo. Anyway I'm not even sure what's the use of 2nd example Custom Alphabet so I think I just stay with the first example. Nice, but pretty overkill in most scenarios, unless your project heavily relies on randomly generated codes — dspacejs May 8 '15 at Here is the table showing my research data: Update: I created a simple Heroku app using these functions that returns the token as a JSON response.
float lcg_value (void) lcg_value () Returns a pseudo- random number in the range (0, 1). This function combines two congruence generators with periods of 2 ^ 31 – 85 and 2 ^ 31 – The period of this function is equal to the product of these two primes. Apr 19, · Generate Random Numbers In PHP Programs Source Code. Before sharing source code, I want to say about this program. Basically, this program is created using the PHPrand(min,max);function. The rand()function generates a random integer (know more about PHP rand). Then I printed all numbers using the echo ""command. Dec 30, · The PHP mt_rand is the inbuilt PHP function. Which is used to generate random integer numbers. This function uses the Mersenne Twister algorithm. Syntax. The basic syntax of mt_rand() function is the following: mt_rand(); or mt_rand(min,max); Parameters of mt_rand() function. min: This a first parameter of this function and it is optional. Specifies the minimum/smallest/lowest number to be .
The rand function is used in PHP to generate a random integer. The rand PHP function can also be used to generate a random number within a specific range, such as a number between 10 and If no max limit is specified when using the rand PHP function, the largest integer that can be returned is determined by the getrandmax function, which varies by operating system.
For example, in Windows , the largest number that can be generated is However, you can set a specific range to include higher numbers. The correct syntax for using the rand PHP function is as follows:. Using the syntax as described above, we can make three examples for the rand function in PHP:. As you can see in these examples, the first rand function generates a random number between 10 and 30, the second between 1 and 1 million, and then third without any maximum or minimum number defined.
These are some possible results:. The random numbers generated by this function are not cryptographically secure values, and they should not be used for cryptographic reasons. Note: Beginning with PHP 7. However, the numbers it generates are not cryptographically secure. Share Flipboard Email. Angela Bradley. Computer Science Expert. Angela Bradley is a web designer and programming expert with over 15 years of experience. An expert in iOS software design and development, she specializes in building technical hybrid platforms.