php编写生成酷炫验证码
<span style="color: #008080;"> 1</span> <span style="color: #000000;">php</span><span style="color: #008080;"> 2</span> <span style="color: #800080;">$im</span>=imagecreate(200,100<span style="color: #000000;">);//生成画布</span><span style="color: #008080;"> 3</span> imagecolorallocate(<span style="color: #800080;">$im</span>,0,0,0<span style="color: #000000;">);//背景色</span><span style="color: #008080;"> 4</span> <span style="color: #800080;">$white</span>=imagecolorallocate(<span style="color: #800080;">$im</span>,<span style="color: #008080;">rand</span>(0,255),<span style="color: #008080;">rand</span>(0,255),<span style="color: #008080;">rand</span>(0,255<span style="color: #000000;">));//生成随机颜色</span><span style="color: #008080;"> 5</span> <span style="color: #0000ff;">for</span>(<span style="color: #800080;">$i</span>=0;<span style="color: #800080;">$i</span>$i++<span style="color: #000000;">)</span><span style="color: #008080;"> 6</span> <span style="color: #000000;">{</span><span style="color: #008080;"> 7</span> imageline(<span style="color: #800080;">$im</span>,<span style="color: #008080;">rand</span>(0,200),<span style="color: #008080;">rand</span>(0,100),<span style="color: #008080;">rand</span>(0,200),<span style="color: #008080;">rand</span>(0,100),<span style="color: #800080;">$white</span><span style="color: #000000;">);//生成干扰线条元素</span><span style="color: #008080;"> 8</span> <span style="color: #000000;">}</span><span style="color: #008080;"> 9</span> <span style="color: #0000ff;">for</span>(<span style="color: #800080;">$i</span>=0;<span style="color: #800080;">$i</span>$i++<span style="color: #000000;">)</span><span style="color: #008080;">10</span> <span style="color: #000000;">{</span><span style="color: #008080;">11</span> imagesetpixel(<span style="color: #800080;">$im</span>,<span style="color: #008080;">rand</span>(0,200),<span style="color: #008080;">rand</span>(0,100),<span style="color: #800080;">$white</span><span style="color: #000000;">);//生成干扰点元素</span><span style="color: #008080;">12</span> <span style="color: #000000;">}</span><span style="color: #008080;">13</span> <span style="color: #0000ff;">for</span>(<span style="color: #800080;">$i</span>=0,<span style="color: #800080;">$str</span>='';<span style="color: #800080;">$i</span>$i++<span style="color: #000000;">)//通过循环获得四个字符</span><span style="color: #008080;">14</span> <span style="color: #000000;">{</span><span style="color: #008080;">15</span> <span style="color: #0000ff;">switch</span>(<span style="color: #008080;">rand</span>(1,3<span style="color: #000000;">))</span><span style="color: #008080;">16</span> <span style="color: #000000;"> {</span><span style="color: #008080;">17</span> <span style="color: #0000ff;">case</span>'1':<span style="color: #008080;">18</span> <span style="color: #800080;">$ch</span>=<span style="color: #008080;">rand</span>(0,9<span style="color: #000000;">);</span><span style="color: #008080;">19</span> <span style="color: #0000ff;">break</span><span style="color: #000000;">; </span><span style="color: #008080;">20</span> <span style="color: #0000ff;">case</span>'2':<span style="color: #008080;">21</span> <span style="color: #800080;">$ch</span>=<span style="color: #008080;">sprintf</span>('%c',<span style="color: #008080;">rand</span>(97,122<span style="color: #000000;">));</span><span style="color: #008080;">22</span> <span style="color: #0000ff;">break</span><span style="color: #000000;">;</span><span style="color: #008080;">23</span> <span style="color: #0000ff;">case</span>'3':<span style="color: #008080;">24</span> <span style="color: #800080;">$ch</span>=<span style="color: #008080;">sprintf</span>('%c',<span style="color: #008080;">rand</span>(65,90<span style="color: #000000;">));</span><span style="color: #008080;">25</span> <span style="color: #0000ff;">break</span><span style="color: #000000;">;</span><span style="color: #008080;">26</span> <span style="color: #000000;"> }</span><span style="color: #008080;">27</span> <span style="color: #800080;">$str</span>.=<span style="color: #800080;">$ch</span><span style="color: #000000;">;</span><span style="color: #008080;">28</span> <span style="color: #008080;">29</span> <span style="color: #000000;">}</span><span style="color: #008080;">30</span> imagettftext(<span style="color: #800080;">$im</span>,32,<span style="color: #008080;">rand</span>(0,15),55,70,<span style="color: #800080;">$white</span>,'c.ttc',<span style="color: #800080;">$str</span><span style="color: #000000;">);//在画布上输出字符串</span><span style="color: #008080;">31</span> <span style="color: #008080;">header</span>("Content-type:image/jpeg"<span style="color: #000000;">);</span><span style="color: #008080;">32</span> imagejpeg(<span style="color: #800080;">$im</span><span style="color: #000000;">);</span><span style="color: #008080;">33</span> imagedestroy(<span style="color: #800080;">$im</span><span style="color: #000000;">);</span><span style="color: #008080;">34</span> ?>
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在使用Golang进行开发或学习过程中,我们可能会遇到undefined:rand.Seed的错误提示。这个错误通常会在需要使用随机数生成器时出现,因为在Golang中需要先设置一个随机数种子,才能使用rand包中的函数。本篇文章将介绍如何解决这种错误。1.引入math/rand包首先,我们需要在代码中引入math/rand包。在

在Go并发编程中同步随机数生成:使用互斥锁(sync.Mutex)控制对rand.Rand随机数生成器的访问。每个goroutine在生成随机数前获取互斥锁,并在生成后释放互斥锁。这确保了同一时间只有一个goroutine可以访问随机数生成器,消除了数据争用。

rand()函数在每次调用时使用相同的初始种子(seeds)。预设的初始种子是从操作系统的时间获得的,但是它只有微秒级的精度。也就是说,在极短的时间内,许多rand()函数调用都将使用相同的初始种子,从而导致相同的随机数生成。那么,如何解决这个问题呢?

在PHP中使用switch语句来进行多个分支的选择是很常见的,通常在每个分支结束后会使用break语句来退出switch语句。然而,有些情况下我们不想使用break语句,本文将介绍在PHP switch语句中不使用break的情况。

在Go语言中,break停止语句用于循环语句中跳出循环,并开始执行循环之后的语句。break语句可以结束for、switch和select的代码块,另外break语句还可以在语句后面添加标签,表示退出某个标签对应的代码块,标签要求必须定义在对应的 for、switch和select的代码块上。

在php中,break用于跳出当前的语法结构,执行下面的语句;可以在switch、for、while和do while等语句中使用,可以终止循环体的代码并立即跳出当前的循环,执行循环之后的代码。break语句可以带一个参数n,表示跳出循环的层数,如果要跳出多重循环的话,可以用n来表示跳出的层数,如果不带参数默认是跳出本重循环。

在之前的文章中,我们带大家学习了JS中的几种循环控制结构(while和do-while循环、for循环),下面聊聊跳出循环语句break和continue,希望对大家有所帮助!

PHP中rand函数的随机性研究与分析随机数在计算机编程中有着广泛的应用,而PHP中的rand函数是用来生成随机整数的常用方法之一。本文将探讨PHP中rand函数的随机性,并通过具体的代码示例来分析其生成随机数的特点。一、PHP中rand函数的简介在PHP中,rand函数可以用来生成指定范围内的随机整数。其基本语法如下所示:intrand(int$min


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