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();
}The above is the detailed content of Tutorial on writing a pure digital verification code in PHP. For more information, please follow other related articles on the PHP Chinese website!
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