PHP generates cool four-character verification code_php tips

The example in this article is to share with you the implementation code of generating verification code in PHP for your reference. The specific content is as follows

<&#63;php
$im=imagecreate(200,100);//生成画布
imagecolorallocate($im,0,0,0);//背景色
$white=imagecolorallocate($im,rand(0,255),rand(0,255),rand(0,255));//生成随机颜色
for($i=0;$i<9;$i++)
{
 imageline($im,rand(0,200),rand(0,100),rand(0,200),rand(0,100),$white);//生成干扰线条元素
}
for($i=0;$i<150;$i++)
{
 imagesetpixel($im,rand(0,200),rand(0,100),$white);//生成干扰点元素
}
for($i=0,$str='';$i<4;$i++)//通过循环获得四个字符
{
 switch(rand(1,3))
 {
  case'1':
  $ch=rand(0,9);
  break; 
  case'2':
  $ch=sprintf('%c',rand(97,122));
  break;
  case'3':
  $ch=sprintf('%c',rand(65,90));
  break;
 }
  $str.=$ch;

}
imagettftext($im,32,rand(0,15),55,70,$white,'c.ttc',$str);//在画布上输出字符串
header("Content-type:image/jpeg");
imagejpeg($im);
imagedestroy($im);
&#63;>

The above is the entire content of this article. I hope it will be helpful to everyone in learning PHP programming.