?php
/*PHP實(shí)現(xiàn)驗(yàn)證碼*/
session_start();//開(kāi)啟會(huì)話
//創(chuàng)建畫(huà)布
$image=imagecreatetruecolor(100,38);
//背景顏色
$bgcolor=imagecolorallocate($image,255,255,255);
imagefill($image,0,0,$bgcolor);
$captch_code='';//存儲(chǔ)驗(yàn)證碼
//隨機(jī)選取4個(gè)數(shù)字
for($i=0;$i4;$i++){
  $fontsize=10;    //
  $fontcolor=imagecolorallocate($image,rand(0,120),rand(0,120),rand(0,120));//隨機(jī)顏色
  $fontcontent=rand(0,9);
  $captch_code.=$fontcontent;
  $x=($i*100/4)+rand(5,10);  //隨機(jī)坐標(biāo)
  $y=rand(5,10);
  imagestring($image,$fontsize,$x,$y,$fontcontent,$fontcolor);
}
/*//字母和數(shù)字混合驗(yàn)證碼
for($i=0;$i4;$i++) {
  $fontsize = 10;    //
  $fontcolor = imagecolorallocate($image, rand(0, 120), rand(0, 120), rand(0, 120));//??????
  $data = 'abcdefghijklmnopqrstuvwxyz1234567890';  //數(shù)據(jù)字典
  $fontcontent = substr($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);
}*/
$_SESSION['code']=$captch_code;
//增加干擾點(diǎn)
for($i=0;$i200;$i++){
  $pointcolor=imagecolorallocate($image,rand(50,200),rand(50,200),rand(50,200));
  imagesetpixel($image,rand(1,99),rand(1,29),$pointcolor);//
}
//增加干擾線
for($i=0;$i3;$i++){
  $linecolor=imagecolorallocate($image,rand(80,280),rand(80,220),rand(80,220));
  imageline($image,rand(1,99),rand(1,29),rand(1,99),rand(1,29),$linecolor);
}
//輸出格式
header('content-type:image.png');
imagepng($image);
//銷毀圖片
imagedestroy($image);

input type="text" placeholder="驗(yàn)證碼" name="verifycode" class="captcha">br>br>
img id="captcha_img" src="captcha.php?r=?php echo rand();?>" alt="驗(yàn)證碼">
label>a href="javascript:void(0)" rel="external nofollow" onclick="document.getElementById('captcha_img').src='captcha.php?r='+Math.random()">換一個(gè)/a> /label>