php验证码怎么做？

推荐学习PHP开发验证码教程

1.创建验证码底图

<?php
$image = imagecreatetruecolor(100,30);
$bgcolor = imagecolorallocate($image,000,255,255);//#FFFFFFFFFFFF
imagefill($image,0,0,$bgcolor);

header('content-type: image/png');
imagepng($image);
//销毁
imagedestroy($image);
?>

课程链接：http://www.gxlcms.com/code/3872.html

2.实现数字验证码

<?php
$image = imagecreatetruecolor(100,30);
$bgcolor = imagecolorallocate($image,255,255,255);//#FFFFFFFFFFFF
imagefill($image,0,0,$bgcolor);
for ($i=0;$i<4;$i++){
 $fontsize = 6;
 $fontcolor = imagecolorallocate($image,rand(0,120),rand(0,120),rand(0,120));
 $fontcontent = rand(0,9);
 $x = ($i * 100/4)+rand(5,10);
 $y = rand(5,10);
 imagestring($image,$fontsize,$x,$y,$fontcontent,$fontcolor);
}
header('content-type: image/png');
imagepng($image);
//销毁
imagedestroy($image);

?>

课程链接：http://www.gxlcms.com/code/3874.html

3.增加干扰元素

<?php
$image = imagecreatetruecolor(100,30);
$bgcolor = imagecolorallocate($image,255,255,255);//#FFFFFFFFFFFF
imagefill($image,0,0,$bgcolor);
for ($i=0;$i<4;$i++){
 $fontsize = 6;
 $fontcolor = imagecolorallocate($image,rand(0,120),rand(0,120),rand(0,120));
 $fontcontent = rand(0,9);
 $x = ($i * 100/4)+rand(5,10);
 $y = rand(5,10);
 imagestring($image,$fontsize,$x,$y,$fontcontent,$fontcolor);
}
for($i=0;$i<200;$i++){
 $pointcolor = imagecolorallocate($image,rand(50,200),rand(50,200),rand(50,200));
 imagesetpixel($image,rand(1,99),rand(1,29),$pointcolor);
}
header('content-type: image/png');
imagepng($image);
//销毁
imagedestroy($image);
?>

课程链接：http://www.gxlcms.com/code/3875.html

4.字母和数字混合验证码

<?php
$image = imagecreatetruecolor(100,30);
$bgcolor = imagecolorallocate($image,255,255,255);//#FFFFFFFFFFFF
imagefill($image,0,0,$bgcolor);
for ($i=0;$i<4;$i++){
 $fontsize = 6;
 $fontcolor = imagecolorallocate($image,rand(0,120),rand(0,120),rand(0,120));
 $data='abcdefghijklmnopqrstuvwxyz1234567890';
 $fontcontent=substr($data,rand(0,strlen($data)),1);
 $x = ($i * 100/4)+rand(5,10);
 $y = rand(5,10);
 imagestring($image,$fontsize,$x,$y,$fontcontent,$fontcolor);
}
for($i=0;$i<200;$i++){
 $pointcolor = imagecolorallocate($image,rand(50,200),rand(50,200),rand(50,200));
 imagesetpixel($image,rand(1,99),rand(1,29),$pointcolor);
}
for($i=0;$i<8;$i++){
 $linecolor = imagecolorallocate($image,rand(60,220),rand(60,220),rand(60,220));
 imageline($image,rand(1,99),rand(1,29),rand(1,99),rand(1,29),$linecolor);
}
header('content-type: image/png');
imagepng($image);
//销毁
imagedestroy($image);

?>

课程链接：http://www.gxlcms.com/code/3878.html

5.使用session存储验证信息

<?php
session_start();
$image = imagecreatetruecolor(100,30);
$bgcolor = imagecolorallocate($image,255,255,255);//#FFFFFFFFFFFF
imagefill($image,0,0,$bgcolor);
$captch_code="";
for ($i=0;$i<4;$i++){
 $fontsize = 6;
 $fontcolor = imagecolorallocate($image,rand(0,120),rand(0,120),rand(0,120));
 $data='abcdefghijklmnopqrstuvwxyz1234567890';
 $fontcontent=substr($data,rand(0,strlen($data)),1);
 $captch_code.="$fontcontent";
 $x = ($i * 100/4)+rand(5,10);
 $y = rand(5,10);
 imagestring($image,$fontsize,$x,$y,$fontcontent,$fontcolor);
}
$_SESSION['code']=$captch_code;
for($i=0;$i<200;$i++){
 $pointcolor = imagecolorallocate($image,rand(50,200),rand(50,200),rand(50,200));
 imagesetpixel($image,rand(1,99),rand(1,29),$pointcolor);
}
for($i=0;$i<8;$i++){
 $linecolor = imagecolorallocate($image,rand(60,220),rand(60,220),rand(60,220));
 imageline($image,rand(1,99),rand(1,29),rand(1,99),rand(1,29),$linecolor);
}
header('content-type: image/png');
imagepng($image);
//销毁
imagedestroy($image);
?>

课程链接：http://www.gxlcms.com/code/3879.html

6.验证码的使用

<?php
session_start();
$image = imagecreatetruecolor(100,30);
$bgcolor = imagecolorallocate($image,255,255,255);//#FFFFFFFFFFFF
imagefill($image,0,0,$bgcolor);
$captch_code="";
for ($i=0;$i<4;$i++){
 $fontsize = 6;
 $fontcolor = imagecolorallocate($image,rand(0,120),rand(0,120),rand(0,120));
 $data='abcdefghijklmnopqrstuvwxyz1234567890';
 $fontcontent=substr($data,rand(0,strlen($data)),1);
 $captch_code.="$fontcontent";
 $x = ($i * 100/4)+rand(5,10);
 $y = rand(5,10);
 imagestring($image,$fontsize,$x,$y,$fontcontent,$fontcolor);
}
$_SESSION['code']=$captch_code;
for($i=0;$i<200;$i++){
 $pointcolor = imagecolorallocate($image,rand(50,200),rand(50,200),rand(50,200));
 imagesetpixel($image,rand(1,99),rand(1,29),$pointcolor);
}
for($i=0;$i<5;$i++){
 $linecolor = imagecolorallocate($image,rand(60,220),rand(60,220),rand(60,220));
 imageline($image,rand(1,99),rand(1,29),rand(1,99),rand(1,29),$linecolor);
}
header('content-type: image/png');
imagepng($image);
//销毁
imagedestroy($image);
?>

课程链接：http://www.gxlcms.com/code/4832.html

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