<?php    session_start ();    header ( 'Content-type: image/png' );    //創建圖片    $im = imagecreate($x=130,$y=45 );    $bg = imagecolorallocate($im,rand(50,200),rand(0,155),rand(0,155)); //第一次對 imagecolorallocate() 的調用會給基于調色板的圖像填充背景色    $fontColor = imageColorAllocate ( $im, 255, 255, 255 );  //字體顏色    $fontstyle = 'rock.ttf';          //字體樣式，這個可以從c:windowsFonts文件夾下找到，我把它放到和authcode.php文件同一個目錄，這里可以替換其他的字體樣式    //產生隨機字符    for($i = 0; $i < 4; $i ++) {        $randAsciiNumArray     = array (rand(48,57),rand(65,90));        $randAsciiNum         = $randAsciiNumArray [rand ( 0, 1 )];        $randStr             = chr ( $randAsciiNum );        imagettftext($im,30,rand(0,20)-rand(0,25),5+$i*30,rand(30,35),$fontColor,$fontstyle,$randStr);        $authcode            .= $randStr;    }    $_SESSION['authcode']    = $randFourStr;//用戶和用戶輸入的驗證碼做比較    //干擾線    for ($i=0;$i<8;$i++){        $lineColor    = imagecolorallocate($im,rand(0,255),rand(0,255),rand(0,255));        imageline ($im,rand(0,$x),0,rand(0,$x),$y,$lineColor);    }    //干擾點    for ($i=0;$i<250;$i++){        imagesetpixel($im,rand(0,$x),rand(0,$y),$fontColor);    }    imagepng($im);    imagedestroy($im);?>

//首先開啟sessionsession_start();//定義前臺顯示驗證碼長&寬$image_width = 120;$image_height = 40;$characters_on_image = 6;$font = './monofont.ttf';//The characters that can be used in the CAPTCHA code.//avoid confusing characters (l 1 and i for example)$possible_letters = '23456789bcdfghjkmnpqrstvwxyz';$random_dots = 10;$random_lines = 30;$captcha_text_color="0x142864";$captcha_noice_color = "0x142864";//定義要生成驗證碼的字符串$code = '';$i = 0;while ($i < $characters_on_image) {$code .= substr($possible_letters, mt_rand(0, strlen($possible_letters)-1), 1);$i++;}$font_size = $image_height * 0.75;$image = @imagecreate($image_width, $image_height);/* setting the background, text and noise colours here */$background_color = imagecolorallocate($image, 255, 255, 255);$arr_text_color = hexrgb($captcha_text_color);$text_color = imagecolorallocate($image, $arr_text_color['red'],    $arr_text_color['green'], $arr_text_color['blue']);$arr_noice_color = hexrgb($captcha_noice_color);$image_noise_color = imagecolorallocate($image, $arr_noice_color['red'],    $arr_noice_color['green'], $arr_noice_color['blue']);/* generating the dots randomly in background */for( $i=0; $i<$random_dots; $i++ ) {imagefilledellipse($image, mt_rand(0,$image_width), mt_rand(0,$image_height), 2, 3, $image_noise_color);}/* generating lines randomly in background of image */for( $i=0; $i<$random_lines; $i++ ) {imageline($image, mt_rand(0,$image_width), mt_rand(0,$image_height), mt_rand(0,$image_width), mt_rand(0,$image_height), $image_noise_color);}/* create a text box and add 6 letters code in it */$textbox = imagettfbbox($font_size, 0, $font, $code);$x = ($image_width - $textbox[4])/2;$y = ($image_height - $textbox[5])/2;imagettftext($image, $font_size, 0, $x, $y, $text_color, $font , $code);/* Show captcha image in the page html page */header('Content-Type: image/jpeg');// defining the image type to be shown in browser widowimagejpeg($image);//showing the imageimagedestroy($image);//destroying the image instance//設置session，做驗證$_SESSION['6_letters_code'] = $code;function hexrgb ($hexstr){ $int = hexdec($hexstr); return array("red" => 0xFF & ($int >> 0x10),        "green" => 0xFF & ($int >> 0x8),        "blue" => 0xFF & $int);}

<?phpsession_start();if(isset($_REQUEST['Submit'])){  // code for check server side validation  if(emptyempty($_SESSION['6_letters_code'] ) ||    strcasecmp($_SESSION['6_letters_code'], $_POST['6_letters_code']) != 0)  {    $msg="您輸入的驗證碼有誤，請重新輸入!";  }else{    echo "您輸入的是正確的!";    // Captcha verification is Correct. Final Code Execute here!  }}?><style type="text/css">.table{  font-family:Arial, Helvetica, sans-serif;  font-size:12px;  color:#333;  background-color:#E4E4E4;}.table td{  background-color:#F8F8F8;}</style><form action="" method="post" name="form1" id="form1" > <table width="400" border="0" align="center" cellpadding="5" cellspacing="1"><?php if(isset($msg)){?>  <tr>   <td colspan="2" align="center" valign="top"><?php echo $msg;?></td>  </tr><?php } ?>  <tr>   <td align="right" valign="top"> 驗證碼Demo:</td>   <td><img src="captcha_code_file.php?rand=<?php echo rand(0,20);?>" id='captchaimg' onclick="refreshCaptcha();" ><br>    <label for='message'>請輸入驗證碼:</label>    <br>    <input id="6_letters_code" name="6_letters_code" type="text">    <br>    如果看不到，請 <a href='javascript： refreshCaptcha();'>點我</a> 刷新一下!    </p></td>  </tr>  <tr>   <td>&nbsp;</td>   <td><input name="Submit" type="submit" onclick="return validate();" value="Submit"></td>  </tr> </table></form><script type='text/javascript'>//定義的刷新請求function refreshCaptcha(){  var img = document.images['captchaimg'];  img.src = img.src.substring(0,img.src.lastIndexOf("?"))+"?rand="+Math.random()*1000;}</script>

<?session_start();?><FORM METHOD=POST ACTION=""><input type=text name=number maxlength=4><img src="YanZhengMa.php?act=init"><INPUT TYPE="submit" name="sub"></FORM><?//檢驗校驗碼if(isset($HTTP_POST_VARS["sub"])):if($HTTP_POST_VARS["number"] != $HTTP_SESSION_VARS[login_check_number] || emptyempty($HTTP_POST_VARS["number"])){  echo "校驗碼不正確!" ;}else{  echo"驗證碼通過！";}endif;show_source('test.php');//以上本頁的源碼//以下是生成驗證碼的源碼show_source('YanZhengMa.php');?><?phpsession_start();session_register("login_check_number");//昨晚看到了chianren上的驗證碼效果，就考慮了一下，用PHP的GD庫完成了類似功能//先成生背景，再把生成的驗證碼放上去$img_height=120;  //先定義圖片的長、寬$img_width=40;if($HTTP_GET_VARS["act"]== "init"){  //srand(microtime() * 100000);//PHP420后，srand不是必須的  for($Tmpa=0;$Tmpa<4;$Tmpa++){    $nmsg.=dechex(rand(0,15));  }//by sports98  $HTTP_SESSION_VARS[login_check_number] = $nmsg;  //$HTTP_SESSION_VARS[login_check_number] = strval(mt_rand("1111","9999"));  //生成4位的隨機數，放入session中  //誰能做下補充，可以同時生成字母和數字啊？？----由sports98完成了  $aimg = imageCreate($img_height,$img_width);  //生成圖片  ImageColorAllocate($aimg, 255,255,255);      //圖片底色，ImageColorAllocate第1次定義顏色PHP就認為是底色了  $black = ImageColorAllocate($aimg, 0,0,0);    //定義需要的黑色  ImageRectangle($aimg,0,0,$img_height-1,$img_width-1,$black);//先成一黑色的矩形把圖片包圍  //下面該生成雪花背景了，其實就是在圖片上生成一些符號  for ($i=1; $i<=100; $i++) {  //先用100個做測試    imageString($aimg,1,mt_rand(1,$img_height),mt_rand(1,$img_width),"*",imageColorAllocate($aimg,mt_rand(200,255),mt_rand(200,255),mt_rand(200,255)));    //哈，看到了吧，其實也不是雪花，就是生成＊號而已。為了使它們看起來"雜亂無章、5顏6色"，就得在1個1個生成它們的時候，讓它們的位置、顏色，甚至大小都用隨機數，rand()或mt_rand都可以完成。  }  //上面生成了背景，現在就該把已經生成的隨機數放上來了。道理和上面差不多，隨機數1個1個地放，同時讓他們的位置、大小、顏色都用成隨機數~~  //為了區別于背景，這里的顏色不超過200，上面的不小于200  for ($i=0;$i<strlen($HTTP_SESSION_VARS[login_check_number]);$i++){    imageString($aimg, mt_rand(3,5),$i*$img_height/4+mt_rand(1,10),mt_rand(1,$img_width/2), $HTTP_SESSION_VARS[login_check_number][$i],imageColorAllocate($aimg,mt_rand(0,100),mt_rand(0,150),mt_rand(0,200)));  }  Header("Content-type: image/png");  //告訴瀏覽器，下面的數據是圖片，而不要按文字顯示  ImagePng($aimg);          //生成png格式。。。嘿嘿效果蠻像回事的嘛。。。  ImageDestroy($aimg);}?>