這是沒開session的效果（可以正常顯示驗證碼的圖片）

---------------------------華麗麗的分割線------------------------------------------

這是打開session以后的效果（沒有圖片顯示）

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請問這是為什么

源碼敬上

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<?php

session_start();

$width = 300;

$height = 100;

$img = imagecreatetruecolor($width,$height);

$white = imagecolorallocate($img, 255, 255, 255);

$red = imagecolorallocate($img, 255, 0, 0);

imagefilledrectangle($img, 0, 0, $width, $height, setColor($img));

function setColor($img)

{

return imagecolorallocate($img,getColor(),getColor(),getColor());

}

function getColor()

{

return mt_rand(0,255);

}

function setNum($a,$b)

{

return mt_rand($a,$b);

}

function getCode()

{

return $string = join('',array_rand(array_flip(array_merge(range(0,9),range('a','z'),range('A','Z'))),4));

}

$str = getCode();

$_SESSION['verifycode'] = $str;

for($i=0;$i<4;$i++)

{

$size = setNum(20,50);

$angle = setNum(-15,15);

$x = ($width/4)*$i+mt_rand(1,9);

$y = mt_rand(($height/2),$height);

$color = setColor( $img );

$fontfile = './fonts/MSYH.ttf';

$text = mb_substr(getCode(),$i,1,'utf-8');

imagettftext($img, $size, $angle, $x, $y, $color, $fontfile, $text);

}

for($i=0;$i<1500;$i++)

{

imagesetpixel($img, mt_rand(0, $width), mt_rand(0, $height) ), setColor($img));

}

for($i=0;$i<3;$i++)

{

imageline($img, mt_rand(0, $width), mt_rand(0,$height), mt_rand(0, $width), mt_rand(0,$height), setColor($img));

}

for($i=0;$i<3;$i++)

{

$cx = mt_rand(0, $width ）；

$cy = mt_rand(0, $height);

$width = mt_rand(0, $width/2);

$height = mt_rand(0, $高度/2);

$start = mt_rand(0, 360);

$end = mt_rand(0, 360);

$color = setColor($img ）；

imagearc($img, $cx, $cy, $width, $height, $start, $end, $color);

}

header('content-type:image/jpeg');

imagejpeg( $img );

imagedestroy( $img );

？>

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