为什么我这个代码输出的验证码是在中间的，而且<img src="getVerify.php" alt="" "/>这个没有显示出验证码
<?php
require_once 'string.func.php';
//通过GD库做验证码
function verifyImage($type=3,
$length=4,$sess_name="verify"){
session_start();
//创建画布
$width=80;
$height=28;
$image=imagecreatetruecolor( $width, $height );
$white = imagecolorallocate( $image, 255, 255, 255 );
$black = imagecolorallocate( $image, 0, 0, 0 );
//用填充矩形填充画布
imagefilledrectangle( $image, 1, 1, $width-2, $height-2, $white );
$type=3;
$length=4;
$chars = buildRandomString( $type, $length );
$sess_name="verify";
$_SESSION [$sess_name] = $chars;
$fontfiles=array("msyhbd.ttc","msyh.ttc","msyhl.ttc","simfang.ttf","simhei.ttf","simkai.ttf","simsun.ttc","wingding.ttf");
for($i=0;$i<$length;$i++){
$size=mt_rand(14,18);
$angle=mt_rand(-15,15);
$x=5+$i*$size;
$y=mt_rand(20,26);
$fontfile="fonts/".$fontfiles[mt_rand(0,count($fontfiles)-1)];
$color=imagecolorallocate($image, mt_rand(50,90), mt_rand(80,200), mt_rand(90,180));
$text=substr($chars, $i,1);
imagettftext($image, $size, $angle, $x, $y, $color, $fontfile, $text);
}
$pixel=10;
if($pixel){
for($i=0;$i<50;$i++){
imagesetpixel($image, mt_rand(0,$width-1),mt_rand(0,$height-1), $black);
}//加黑点
}
$line=4;
if($line){
$color=imagecolorallocate($image, mt_rand(50,90), mt_rand(80,200), mt_rand(90,180));
for($i=0;$i<$line;$i++){
imageline($image, mt_rand(0,$width-1),mt_rand(0,$height-1), mt_rand(0,$width-1),mt_rand(0,$height-1), $color);
}//加斜线
}
ob_clean();//消除之前的输出
header("content-type:image/gif");//定义验证码图片类型
imagegif($image);//显示图片资源
imagedestroy($image);//销毁资源
}
?>
