/*** 验证码 ***/

require_once'string.func.php';

//通过GD库做验证码

function verifyImage($type=1,$length=4,$pixel=0,$line=0,$sess_name = "verify"){

//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 );

$chars = buildRandomString ( $type, $length );

$_SESSION [$sess_name] = $chars;

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 );

$color = imagecolorallocate ( $image, mt_rand ( 50, 90 ), mt_rand ( 80, 200 ), mt_rand ( 90, 180 ) );

$text = substr ( $chars, $i, 1 );

imagestring ( $image, $size, $angle, $x, $y, $color,$text );

}

if ($pixel) {

for($i = 0; $i < 50; $i ++) {

imagesetpixel ( $image, mt_rand ( 0, $width - 1 ), mt_rand ( 0, $height - 1 ), $black );

}

}

if ($line) {

for($i = 1; $i < $line; $i ++) {

$color = imagecolorallocate ( $image, mt_rand ( 50, 90 ), mt_rand ( 80, 200 ), mt_rand ( 90, 180 ) );

imageline ( $image, mt_rand ( 0, $width - 1 ), mt_rand ( 0, $height - 1 ), mt_rand ( 0, $width - 1 ), mt_rand ( 0, $height - 1 ), $color );

}

}

ob_clean();

header ( "content-type:image/gif" );

imagegif ( $image );

imagedestroy ( $image );

}

帮我看看哪里错了