我也是这个问题，你解决了吗，教教我呗么么哒

<?php

function buildRandomString($type=1,$length=4){

if($type==1){

$chars=join("",range(0,9));

}elseif($type==2){

$chars=join("",array_merge(range("a","z"),range("A","Z")));

}elseif($type==3){

$chars=join("",array_merge(range("a","z"),range("A","Z"),range(0,9)));

}

if($length>strlen($chars)){

exit ("字符长度不够");

}

$chars=str_shuffle($chars);

return substr($chars,0,$length);

}

<?php

require_once 'string.func.php';

$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("simfang.ttf","simhei.ttf","simkai.ttf","方正狂草.ttf","方正粗活意简体.ttf","方正细谭黑简体.ttf");

for($i=9;$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=50;

if($pixel){

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

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

}

}

$line=10;

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);

}

}

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

imagegif($image);

imagedestroy($image);