Tutorial on making PHP verification code

Oneself in the past self-taught PHP painting verification code tutorial, now take this part of the notes to share with you, hoping to help Everyone.

incidentally, I will be in the back of the whole set of Css3,php,mysql development Notes pack to Baidu cloud, there is a need to go directly to the Baidu Cloud download, so that after you develop can directly turn the notes without Baidu search so Troublesome.

Note Link: Http://pan.baidu.com/s/1qYdQdKK password: pvj2

The following is mainly from the theory + practice code to explain, followed by code Examples.

first, the introduction of verification code
The CAPTCHA is an abbreviation for the automatic distinction between computer and human Turing Tests. is a public automatic program that distinguishes users from computers and People.

second, The Verification Code application scenario?
(all to distinguish between a person or a machine, shielding a machine request)
A) login, Registration To determine the pre-submission, man/machine check;
B) before the release, reply to the information, man/machine check;
C) when the suspected machine request, the Person/machine check;
..................

third, the core technical analysis of Verification Code service
Implementation Steps:
1. Generate basemaps;
2. Generate Verification content;
3. Generate the Verification code picture;
4. Verifying the contents of the verification;

Technical Points:
　　A) the implementation of the basemap, and the addition of interference elements;
Rely on PHP image processing library GD
Http://php.net/gd
　　B) Generate validation Content
Simple random number generation, using PHP function Mt_rand ();
Random number + letter generation requires the basis of ASCII code theory;
Random Chinese generation, need UTF-8 coding theory foundation;
　　C) Verify that the content is stored on the service side;
PHP Operation Session Basics Required
　　D) Verifying the Content
Requires a front-end Ajax foundation;

Precautions:
A) rely on GD extension
　　※B) before outputting the picture, the image header information must be output in advance;
C) The default output for this method is a black background

From the theoretical section, then follow the steps to write the following code step-by-step:

Example of verification code: ( Basic Verification Code )

1234567891011121314151617181920212223242526272829303132333435363738394041424344454647484950515253545556575859606162636465 666768

<?php    session_start();    // 先制作底图    $image= imagecreatetruecolor(100, 30);    $bgcolor= imagecolorallocate($image, 255, 255, 255);//生成底片颜色,默认为黑色    imagefill($image, 0, 0, $bgcolor);//x,y轴上的位置/*// 在地图上显示随机数字    for($i=0;$i<4;$i++){        $fontsize=6;        $fontcolor = imagecolorallocate($image, rand(0,120), rand(0,120), rand(0,120));        $fontcontent=rand(0,9);//数字0~9        // 关键的部分 (注意事项：控制好字体大小与分布，避免字体重叠或显示不全)        $x=($i*100/4)+rand(5,10); //写在的坐标上        $y=rand(5,10);        imagestring($image, $fontsize, $x, $y, $fontcontent, $fontcolor);    }*//*  //数字和字母验证码    for($i=0;$i<4;$i++){        $fontsize=6;        $fontcolor=imagecolorallocate($image, rand(0,120),rand(0,120), rand(0,120));        $data =‘abcdefghigkmnpqrstuvwxy3456789‘;        $fontcontent=substr($data, rand(0,strlen($data)),1);        $x=($i*100/4+rand(5,10));        $y=rand(5,10);        imagestring($image, $fontsize, $x, $y, $fontcontent, $fontcolor);    }*/        $captch_code="";    //字母验证码    for($i=0;$i<4;$i++){        $fontsize=6;        $fontcolor=imagecolorallocate($image, rand(0,120),rand(0,120), rand(0,120));        $data=‘abcdefghigkmnpqrstuvwxy‘;        $fontcontent=substr($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;    // 添加点的干扰素    for($i=0;$i<200;$i++){        $pointcolor= imagecolorallocate($image, rand(50,200), rand(50,200), rand(50,200));        imagesetpixel($image, rand(1,99), rand(1,29), $pointcolor);    }  // 添加线干扰    for($i=0;$i<3;$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‘);//输出png的图片    imagepng($image);//生成图片    // 销毁图片    imagedestroy($image);?>

　　

After the validation code section of php, it is the code of the display page with the front end:

12345678910111213141516

<!DOCTYPEhtml><htmllang="en"><head>    <metacharset="UTF-8">    <title>登录</title></head><body>    <formaction="reg.php" method="post">    <imgid="captcha_img" src="verify.php?r=<?php echo rand();?>">    <ahref="javascript:void(0);" onclick="document.getElementById(‘captcha_img‘).src=‘verify.php?+Math.random()‘;" title="换一个?">看不清?</a><br>        验证码：<inputtype="text" name="authcode">        <inputtype="submit" >    </form></body></html>

The above is the number of the verification code, the following part of PHP is the image verification code of the page image verification code display :

123456789101112131415161718

<?php    session_start();    // 图片的验证码    $table=array(        "pic0"=>‘狗‘,        "pic1"=>‘猫‘,        "pic2"=>‘鱼‘,        "pic3"=>‘鸟‘        );    $index=rand(0,3);    $value=$table[‘pic‘.$index];    $_SESSION[‘authcode‘]=$value;    $filename=dirname(__FILE__).‘\\pic‘.$index.‘.jpg‘;//需要自己准备好图片！！

1	$contents=file_get_contents($filename); header(‘content-type:image/jpg‘); echo$contents; ?>

　

The following is the display code for Chinese characters:

1234567891011121314151617181920212223242526272829303132333435363738394041424344454647

汉字的验证码:<?php    session_start();    // 先制作底图    $image= imagecreatetruecolor(200, 60);    $bgcolor= imagecolorallocate($image, 255, 255, 255);//生成底片颜色,默认为黑色    imagefill($image, 0, 0, $bgcolor);//x,y轴上的位置    $fontface=‘msyh.ttf‘;    $str="刘恒春美女帅哥看这里来好样的我知道了是";    $strdb=str_split($str,3);//每三个长算一个汉字    header("content-type:text/html;charset=‘utf8‘");    $captch_code="";    //中文验证码    for($i=0;$i<4;$i++){        $fontcolor=imagecolorallocate($image, rand(0,120),rand(0,120), rand(0,120));        $index=rand(0,count($strdb));        $cn=$strdb[$index];        $captch_code.=$cn;        imagettftext($image, mt_rand(20,24), mt_rand(-60,60), (40*$i+20), mt_rand(30,35),$fontcolor,$fontface,$cn);    }    $_SESSION[‘authcode‘]=$captch_code;    // 添加点的干扰素    for($i=0;$i<200;$i++){        $pointcolor= imagecolorallocate($image, rand(50,200), rand(50,200), rand(50,200));        imagesetpixel($image, rand(1,199), rand(1,59), $pointcolor);    }  // 添加线干扰    for($i=0;$i<3;$i++){        $linecolor=imagecolorallocate($image, rand(80,220), rand(80,220),rand(80,220));        imageline($image, rand(1,199),rand(1,59), rand(1,199),rand(1,59),$linecolor);    }    header(‘content-type:image/png‘);//输出png的图片    imagepng($image);//生成图片    // 销毁图片    imagedestroy($image);    ?>

　　

All in all is the verification code code summary, if necessary can be in the Baidu cloud below me to download the corresponding Notes.

Note Link: Http://pan.baidu.com/s/1qYdQdKK password: pvj2

Tutorial on making PHP verification code