Tutorial on writing a pure digital verification code in PHP
Now let’s talk about the simple pure digital verification code.
If you are a beginner, it is recommended to follow the comments //numbers of my code step by step. The easiest way is to copy the entire code.
Create a new captcha.php:
<?php //11>设置session,必须处于脚本最顶部 session_start(); /*$image = imagecreatetruecolor(100, 30); //1>设置验证码图片大小的函数 //5>设置验证码颜色 imagecolorallocate(int im, int red, int green, int blue); $bgcolor = imagecolorallocate($image,255,255,255); //#ffffff //6>区域填充 int imagefill(int im, int x, int y, int col) (x,y) 所在的区域着色,col 表示欲涂上的颜色 imagefill($image, 0, 0, $bgcolor); //10>设置变量 $captcha_code = "";*/ //7>生成随机数字 for($i=0;$i<4;$i++){ //设置字体大小 $fontsize = 6; //设置字体颜色,随机颜色 $fontcolor = imagecolorallocate($image, rand(0,120),rand(0,120), rand(0,120)); //0-120深颜色 //设置数字 $fontcontent = rand(0,9); //10>.=连续定义变量 $captcha_code .= $fontcontent; //设置坐标 $x = ($i*100/4)+rand(5,10); $y = rand(5,10); imagestring($image,$fontsize,$x,$y,$fontcontent,$fontcolor); } //10>存到session $_SESSION['authcode'] = $captcha_code; //8>增加干扰元素,设置雪花点 for($i=0;$i<200;$i++){ //设置点的颜色,50-200颜色比数字浅,不干扰阅读 $pointcolor = imagecolorallocate($image,rand(50,200), rand(50,200), rand(50,200)); //imagesetpixel — 画一个单一像素 imagesetpixel($image, rand(1,99), rand(1,29), $pointcolor); } //9>增加干扰元素,设置横线 for($i=0;$i<4;$i++){ //设置线的颜色 $linecolor = imagecolorallocate($image,rand(80,220), rand(80,220),rand(80,220)); //设置线,两点一线 imageline($image,rand(1,99), rand(1,29),rand(1,99), rand(1,29),$linecolor); } //2>设置头部,image/png header('Content-Type: image/png'); //3>imagepng() 建立png图形函数 imagepng($image); //4>imagedestroy() 结束图形函数 销毁$image imagedestroy($image); 接着就是静态页的代码了:index.html <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional //EN" "、www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns=" <head><meta http-equiv="Content-Type" content="text/html; charset=utf-8" /><title>无标题文档</title> </head><body><form method="post" action="./form.php"> <p>验证码: <img id="captcha_img" border='1' src='./captcha.php?r=echo rand(); ?>' style="width:100px; height:30px" /> <a href="javascript:void(0)" onclick="document.getElementById('captcha_img').src='./captcha.php?r='+Math.random()">换一个?</a> </p> <P>请输入验证码:<input type="text" name='authcode' value=''/></p> <p><input type='submit' value='提交' style='padding:6px 5px;'/></p></form></body></html> 从index.html可以看到,提交的表单是到form.php的,所以还要有一个判断的form.php代码: <?php header("Content-Type:text/html;charset=utf-8"); //设置头部信息 //isset()检测变量是否设置 if(isset($_REQUEST['authcode'])){ session_start(); //strtolower()小写函数 if(strtolower($_REQUEST['authcode'])== $_SESSION['authcode']){ //跳转页面 echo "<script language=\"javascript\">"; echo "document.location=\"./form.php\""; echo "</script>"; }else{ //提示以及跳转页面 echo "<script language=\"javascript\">"; echo "alert('输入错误!');"; echo "document.location=\"./form.php\""; echo "</script>"; } exit(); }
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