Generate Random String in PHP

In this example, we will generate random string in PHP using multiple methods. PHP does not provide a built-in function for random strings, but we can create them using random numbers.

PHP has three different functions to generate random numbers. These functions accept minimum and maximum values and return a random number from that range. We can combine these numbers to create random string values easily.

Below are three functions that will help us to generate random integer values and we define logic on that.

$randomValue = rand(1, 10);

$randomValue = mt_rand(1, 10);

$randomValue = random_int(1, 10);

Above all functions will return random numbers between 1 to 10.

In the first example, we will use loop-based logic to generate random strings. Where we will define a string variable that contains all allowed characters like 0 to 9, a to z, and A to Z, and create a random string from that.

<?php
    function getRandomString($n = 10) {
        // Define allowed character
        $str = '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ';
        $randomString = '';

        for ($i = 0; $i < $n; $i++) {
            $index = rand(0, strlen($str) - 1);
            $randomString .= $str[$index];
        }

        return $randomString;
    }

    echo getRandomString();
?>

Here, we have created a function that accepts one integer parameter and also defined the default value for it. Then create a string variable and add an allowed character to it. Lastly added a loop that runs till the user-defined value picks a random character from our string and adds it to our random string.

It will produce a similar output to the below:

Srcajksjw

Here, we can also use encryption or hash functions to create a random string. Functions like md5, hash, or sha1 are used to encrypt data using their functionality. Those encrypted values commonly look like random strings.

Let’s take an example to create a random string using an encryption function:

<?php
    function getRandomString(){
        $str = rand();
        return hash("sha256", $str);
    }

    $randomString = getRandomString();
    echo $randomString;

    //2bc8cc1c8cc1f8c8d0eb54210fe52c2d5972e24d11c24748b4def1c5b04fcf18
?>

Here, we can also use uniqid() function to generate a random string in PHP. The uniqid() function in PHP is an inbuilt function that is used to generate a unique ID based on the current time in microseconds.

The use of uniqid() function is quite easy to compare to another. Below is an example of creating random string using uniqid() function:

<?php
    $result = uniqid();
    echo $result;

    //2bzdeb79e4b64
?>

Conclusion

In this article, we have taken a few examples to generate random strings in PHP using different logic like custom function, with the help of random function and uniqid() function. You can use those as per your requirements.

You can also create QR codes dynamically in PHP for your projects. For practical examples, check out our post on Generate QR Code in PHP.