PHP培訓(xùn)之php簡(jiǎn)單生成驗(yàn)證碼

利用php自身帶的函數(shù)來(lái)實(shí)現(xiàn)圖片驗(yàn)證碼生成功能，有需要的朋友可以參考一下。//must start or continue session and save CAPTCHA

string in $_SESSION for 
//it to be available to other requests 
if(!isset($_SESSION)){ 
session_start(); 
header('Cache-control:private'); 
} 
//create a 65*20 pixel image 
$width=65; 
$height=20; 
$image=imagecreate(65,20); 
//fill the image background color 
$bg_color=imagecolorallocate($image,0x33,0x66,0xFF); 
imagefilledrectangle($image,0,0,$width,$height,$bg_color); 
//fetch random text 
$text=random_text(5); 
//determine x and y coordinates for centering text 
$font=5; 
$x=imagesx($image)/2-strlen($text)*imagefontwidth($font)/2; 
$y=imagesy($image)/2-imagefontheight($font)/2; 
//write text on image 
$fg_color=imagecolorallocate($image,0xFF,0xFF,0xFF); 
imagestring($image,$font,$x,$y,$text,$fg_color); 
//save the CAPTCHA string for later comparison 
$_SESSION['captcha']=$text; 
//output the image 
header('Content-type:image/png'); 
imagepng($image); 
imagedestroy($image); 
?>

 

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作者：黑馬程序員PHP培訓(xùn)學(xué)院
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