php rand函数浮点数_Rand（）PHP函数

￡神魔★判官ぃ 2022-12-06 15:27 170阅读 0赞

php rand函数浮点数

The rand() function is used in [PHP][] to generate a random integer. The rand() PHP function can also be used to [generate a random number][] within a specific range, such as a number between 10 and 30.

rand()函数在[PHP中][PHP]用于生成随机整数。 rand()PHP函数还可用于[生成][generate a random number]特定范围内的[随机数][generate a random number] ，例如10到30之间的数字。

If no max limit is specified when using the rand() PHP function, the largest integer that can be returned is determined by the getrandmax() function, which varies by operating system.

如果在使用rand()PHP函数时未指定最大限制，则可返回的最大整数由getrandmax()函数确定，该函数因操作系统而异。

For example, in [Windows][], the largest number that can be generated is 32768. However, you can set a specific range to include higher numbers.

例如，在[Windows中][Windows] ，可以生成的最大数字是32768。但是，您可以设置特定范围以包括更大的数字。

## Rand()语法和示例 **(** Rand() Syntax and Examples **)** ##

The correct syntax for using the rand PHP function is as follows:

使用rand PHP函数的正确语法如下：

rand();

要么

rand(min,max);

Using the syntax as described above, we can make three examples for the rand() function in PHP:

使用上述语法，我们可以为PHP中的rand()函数创建三个示例：

<?php
    echo (rand(10, 30) . "<br>");
    echo (rand(1, 1000000) . "<br>");
    echo (rand());
    ?>

As you can see in these examples, the first rand function generates a random number between 10 and 30, the second between 1 and 1 million, and then third without any maximum or minimum number defined.

从这些示例中可以看到，第一个rand函数生成一个10到30之间的随机数，第二个生成1到1百万之间的随机数，然后生成没有定义任何最大或最小数的第三个随机数。

These are some possible results:

这些是一些可能的结果：

20
    442549
    830380191

## 使用Rand()函数的安全问题 **(** Security Concerns Using Rand() Function **)** ##

The random numbers generated by this function are not cryptographically secure values, and they should not be used for cryptographic reasons. If you need secure values, use other random functions such as random\_int(), openssl\_random\_pseudo\_bytes(), or random\_bytes()

此函数生成的随机数不是加密安全值，出于加密原因，不应使用它们。 如果需要安全值，请使用其他随机函数，例如random\_int()，openssl\_random\_pseudo\_bytes()或random\_bytes()

**Note:** Beginning with PHP 7.1.0, the rand() PHP function is an alias of mt\_rand(). The mt\_rand() function is said to be four times faster and it produces a better random value. However, the numbers it generates are not cryptographically secure. The PHP manual recommends using the random\_bytes() function for cryptographically secure integers.

**注意：**从PHP 7.1.0开始，rand()PHP函数是mt\_rand()的别名。 据说mt\_rand()函数的速度快了四倍，并且产生了更好的随机值。 但是，它生成的数字不是加密安全的。 PHP手册建议对加密安全的整数使用random\_bytes()函数。

> 翻译自: [https://www.thoughtco.com/rand-php-function-2694085][https_www.thoughtco.com_rand-php-function-2694085]

php rand函数浮点数

[PHP]: https://www.thoughtco.com/learn-php-2693925
[generate a random number]: https://www.thoughtco.com/how-to-generate-random-numbers-2034206
[Windows]: https://www.thoughtco.com/unusual-history-of-microsoft-windows-1992140
[https_www.thoughtco.com_rand-php-function-2694085]: https://www.thoughtco.com/rand-php-function-2694085