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The main content of this article is to explain "what is a PHP random function", interested friends may wish to have a look. The method introduced in this paper is simple, fast and practical. Let's let the editor take you to learn "what is a PHP random function"?

II. Preface

PHP is a common scripting language, mainly because it is easy to learn and quick to use. Almost 50% of Web programs have PHP (incomplete statistics). PHP provides rich functions and API interfaces for developing this, which makes it very easy for us to use its powerful built-in functions and extensions. this article is the second in a series of "PHP can do great things" series, which mainly summarizes PHP's knowledge of random number generators.

3. PHP random function

PHP random functions are mainly rand, mt_rand, array_rand, as well as random "arrangement" (disordered) functions shuffle, str_shuffle, can produce a unique ID uniqid.

1. Rand generates random numbers:

The rand () function uses libc's random number generator to generate random numbers, which is generally slow and uncertain, so it is recommended to use the mt_rand function instead.

The getrandmax () function returns the maximum random number that the rand function can produce (my system is 32767), so don't overshoot the return value of getrandmax when setting the second parameter of the rand function.

2. Mt_rand generates random numbers:

Many old libc random number generators have some uncertain and unknown characteristics and are very slow. The rand () function of PHP uses the libc random number generator by default. The mt_rand () function is used informally to replace it. This function uses the properties known in »Mersenne Twister as the random number generator, which can generate random values at an average speed of four times faster than the rand () provided by libc. It is strongly recommended that you use the mt_rand function instead of rand during development.

Returns a pseudorandom number between 0 and mt_getrandmax () if the optional arguments min and max,mt_rand () are not provided. For example, if you want a random number between 3 and 20, including 3 and 20, use mt_rand (3,20).

3. Array_rand function

Array_rand returns random key values in the array, a bit like the mt_rand () function, and the rest is nothing special, just flexible.

4. Shuffle function

Shuffle function is to disrupt the sequence of an array, a little random meaning, here is put in the random function. The return value is a Bool value, which is equivalent to a direct reference to the original variable.

5. Str_shuffle function

Here, the function of str_shuffle is similar to that of shuffle, except that the return value is the original string of str_shuffle.

6. Uniqid function

Uniqid can produce unique strings, and this application can be quite extensive.

At this point, I believe that everyone has a deeper understanding of "what is a PHP random function", might as well come to the actual operation of it! Here is the website, more related content can enter the relevant channels to inquire, follow us, continue to learn!

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