Uniqid () function usage in PHP

This article mainly introduces the usage of uniqid () function in PHP, including the basic usage and Application Analysis of the function, which is a very practical technique. For more information, see

This article mainly introduces the usage of uniqid () function in PHP, including the basic usage and Application Analysis of the function, which is a very practical technique. For more information, see

This example describes how to use the uniqid () function in PHP. Share it with you for your reference. The specific method is analyzed as follows:

The uniqid () function generates a unique ID based on the current time in microseconds.
Note: because the system time is used, the IDS generated through this function are not optimal. To generate an absolutely unique ID, use the md5 () function (please refer to the string function reference ).

The Code is as follows:

<? Php
Echo uniqid ();
?>

In this example, a 32-character unique string is generated.

The Code is as follows:

<? Php
$ Token = md5 (uniqid (rand ()));
Echo $ token;
?>

Uniqid () returns a unique identifier with a prefix based on the current time accurate to microseconds.
It is based on the current time, but it does not explain the relationship with the current time.
Echo uniqid (); we can see that uniqid is always a hexadecimal number with a continuously changing length of 13.

Let's take a look at the following code:

The Code is as follows:

<? Php
Echo hexdec (uniqid ()/(time () + microtime ());
?>

The output is about 1048576.

It can be concluded that uniqid is obtained after the current time is accurate to microsecond and then multiplied by 1048576 (20 power of 2) and finally converted to hexadecimal.
After you know the relationship between uniqid and time, uniqid can be used more widely. For example, you can use uniqid as the Post File name in a forum.

In the post index, you can easily search for a post by time.

Based on the upstream and downstream code, I think his role is to generate a 32-bit non-repeating character.

The uniqid () function is based on the current time in microseconds. Therefore, in the case of high concurrency, repetition may occur, the solution is to generate a random number under this premise, and then combine the two to generate a new number, which will reduce the probability of repetition. If you still want to be more accurate, you can add the Md5 code of the client's IP address to generate the Code together. In this way, the probability of duplication is very low. It can be said that there will be almost no duplication.

The Code is as follows:

<? Php
Function getRand (){
Return uniqid (). rand (1, 100000 );
}
Echo getRand ();
Exit;
?>

I hope this article will help you with PHP programming.