What is the usage of the uniqid function in PHP?

The uniqid function is used to create a unique string identifier. It can take two parameters, the first one being an optional prefix to add some content before the unique identifier. The second parameter is an optional boolean value, set to true if you want the unique identifier to be based on the current time with microsecond precision.

Here is an example of using the uniqid function:

$uniqueId = uniqid(); // 生成一个不带前缀的唯一标识符

$uniqueIdWithPrefix = uniqid('user_'); // 生成一个带有前缀'user_'的唯一标识符

$uniqueIdWithPrefixAndTime = uniqid('order_', true); // 生成一个带有前缀'order_'和基于时间的唯一标识符

The unique identifier generated is typically based on the current time and a unique algorithm of the server. It is important to note that due to the fact that the unique identifier generated by the uniqid function is time-based, calling the uniqid function repeatedly in a very short amount of time may result in the same identifier being generated.