php编程每天必学之验证码,php编程验证码
本文为大家分享了php图片验证码的实现代码,分享给大家供大家参考,具体内容如下
1.验证码图片生成
captcha.php
//1.生成100*30大小的图片,默认为黑色 $image = imagecreatetruecolor(100,30); //创建白色底图 $bgcolor = imagecolorallocate($image,255,255,255); //用白色填充黑色 imagefill ($image,0,0,$bgcolor); //2.随机显示数字或字母 $captch_code = ""; for($i=0;$i<4;$i++){ $fontsize=6; $fontcolor=imagecolorallocate($image,rand(0,120),rand(0,120),rand(0,120)); $data = "abcdefghijkmnpqrstuvwxy3456789"; $fontcontent =substr($data,rand(0,strlen($data)),1); $captch_code .=$fontcontent; $x = ($i*100/4)+rand(5,10); $y = rand(5,10); imagestring($image, $fontsize, $x, $y, $fontcontent,$fontcolor); } $_SESSION["authcode"] = $captch_code; //3.增加干扰 //干扰点 for($i=0;$i<100;$i++){ $pointcolor=imagecolorallocate($image,rand(50,200),rand(50,200),rand(50,200)); imagesetpixel($image,rand(1,99),rand(1,29),$pointcolor); } //干扰线 for($i=0;$i<2;$i++){ $linecolor=imagecolorallocate($image,rand(80,220),rand(80,220),rand(80,220)); imageline($image,rand(1,99),rand(1,29),rand(1,99),rand(1,29),$linecolor); } header("content-type:image/png"); imagepng($image);
2.页面实现验证码功能
form.php
<?php if(isset($_POST["authcode"])){ session_start(); if(strtolower($_POST["authcode"])==$_SESSION["authcode"]){ echo "OK"; }else{ echo "NO"; } } ?> <!doctype html> <html lang="en"> <head> <meta charset="UTF-8"> <title>Document</title> </head> <body> <form action="form.php" method="post"> <p>验证码图片: <img id="img" border="1" src="captcha.php?r=<?php echo rand()? alt="php编程每天必学之验证码,php编程验证码" >" alt=""> <a href="javascript:void(0)" onclick="document.getElementById('img').src='captcha.php?r'+Math.random() ">换一个</a> </p> <p><input type="text" name="authcode"></p> <p><input type="submit" value="提交"></p> </form> </body> </html>
以上就是本文的全部内容,帮助大家轻松实现php图片验证码。
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php把负数转为正整数的方法:1、使用abs()函数将负数转为正数,使用intval()函数对正数取整,转为正整数,语法“intval(abs($number))”;2、利用“~”位运算符将负数取反加一,语法“~$number + 1”。

实现方法:1、使用“sleep(延迟秒数)”语句,可延迟执行函数若干秒;2、使用“time_nanosleep(延迟秒数,延迟纳秒数)”语句,可延迟执行函数若干秒和纳秒;3、使用“time_sleep_until(time()+7)”语句。

php除以100保留两位小数的方法:1、利用“/”运算符进行除法运算,语法“数值 / 100”;2、使用“number_format(除法结果, 2)”或“sprintf("%.2f",除法结果)”语句进行四舍五入的处理值,并保留两位小数。

判断方法:1、使用“strtotime("年-月-日")”语句将给定的年月日转换为时间戳格式;2、用“date("z",时间戳)+1”语句计算指定时间戳是一年的第几天。date()返回的天数是从0开始计算的,因此真实天数需要在此基础上加1。

php判断有没有小数点的方法:1、使用“strpos(数字字符串,'.')”语法,如果返回小数点在字符串中第一次出现的位置,则有小数点;2、使用“strrpos(数字字符串,'.')”语句,如果返回小数点在字符串中最后一次出现的位置,则有。

方法:1、用“str_replace(" ","其他字符",$str)”语句,可将nbsp符替换为其他字符;2、用“preg_replace("/(\s|\ \;||\xc2\xa0)/","其他字符",$str)”语句。

php字符串有下标。在PHP中,下标不仅可以应用于数组和对象,还可应用于字符串,利用字符串的下标和中括号“[]”可以访问指定索引位置的字符,并对该字符进行读写,语法“字符串名[下标值]”;字符串的下标值(索引值)只能是整数类型,起始值为0。

在PHP中,可以利用implode()函数的第一个参数来设置没有分隔符,该函数的第一个参数用于规定数组元素之间放置的内容,默认是空字符串,也可将第一个参数设置为空,语法为“implode(数组)”或者“implode("",数组)”。


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