$chars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789" = substr(parameters) All this should be placed inside a for loop which should loop the length of random string required. substr(parameters) instead we can shortly write it as $string. The value returned should be assigned to $string and st the same time concatenated with the previous values. So the min value parameter of rand() is 0 and max value is the length of all the characters. In this case the string variable is $chars and length is 1 the start_position parameter should be randomly generated using rand() function. The syntax for substr() is substr(string_variable,start_position,length). Using the substr() function a single character is randomly picked from $chars variable. If you don’t assign $string and empty value you’ll get a notice saying “Notice: Undefined variable: string in /path/to/php/file on line xx” if you have display_errors on. Then the variable which will hold the random string value should be assigned an empty value. First lets assign all the uppercase and lowercase alphabets and numbers to a variable named $chars. For this a looping statement can be used. This should be done as many times the length of the random string required. Each time this process is done the currently randomly selected character is concatenated with the previously generated characters. The concept here is to randomly pick a character from the string containing all the characters and assign it to a variable. A variable should be declared containing all the alphabets in English both uppercase and lowercase (A-Z and a-z) and numbers from 0-9. The rand() function in PHP generates a random number we’ll be using this function to generate a random alphanumeric string. All those functions will be used, but only in a different sequence.Īs a last option, I will provide you with two of my functions that can generate a string of the length that we want.įirst function.Generate a random alphanumeric string containing both uppercase and lowercase characters in PHP. The next three options are very similar to the previous option for getting a string. As a final step, we pass this hash of the string to the substr function, which will truncate the string to the length we want by passing in the second parameter, length. In the next step, we pass this set of numbers to the md5 function, which forms the hash of the string. We first get a set of digits by calling the time function which returns the number of seconds since the Unix epoch. The next option to generate a unique string, we will use already three functions, substr, md5 and time. The bin2hex function is designed to convert binary data to a hexadecimal representation, that is, to a regular string. After generating a string in bytes by a further action, this string must be passed to the bin2hex function. In the following example, we will use two functions, random_bytes and bin2hex, to generate a unique string.įirst, the random_bytes function generates cryptographically pseudo-random bytes, the function takes a mandatory length parameter, that is, the length of the generated string in bytes. We've called the uniqid function twice, resulting in two unique strings. This function has two optional parameters that can be passed, but in order for us to generate a unique string, we can additionally not pass anything. The uniqid function generates a unique string based on getting the current time in microseconds. In the very first option, we will use the uniqid function. There are a lot of options in PHP for how to generate a unique string, and I will show you the most common options that developers use. One example where you will need to generate a unique string is a cookie for users who register on your site, and this cookie will be used by the user each time they log in. In today's article, we'll talk about how to generate a unique string in PHP.Īlmost always in your developments you will encounter the fact that you need to generate a unique string of a certain length, and there are a lot of examples of this.
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