PHP Implementation Verification Code

First step: Create a canvas

Step two: Create a color

Step three: Prepare the characters

Fourth step: Write characters on the canvas

Fifth step: Draw the interference line (point)

Sixth step: Output format

Seventh Step: Output picture

Eighth Step: Destroying resources

<?php     verify () function verify ($width  = 100 ,  $height  = 40 ,  $num  = 5 ,  $type  = 3 ) {     1  Create canvas      $image  = imagecreatetruecolor ($width  ,  $height);         //2  Create a color   //because it's always used behind, so I wrote two functions, Lightcolor (light color). , Deepcolor (dark color)             //3  Create character  // Here is the type of your choice,1  is pure digital,2  is a pure small letter, 3  is a mixed number of uppercase and lowercase letters     switch ($type) {         case 1:             //defining strings              $str  =   "0123456789";             //scrambled String               $strNew  = str_shuffle ($STR);             //Interception of $num               $string  = substr ($strNew  , 0 ,  $num);      &NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;BREAK;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;CASE&NBSP;2:             //Defining characters               $arr  = range (' A '  ,  ' z ');             //scrambled string array              shuffle ($arr);             Interception              $tmp  = array_slice ($arr  , 0 ,  $num);             //string               $string  = join ('  ,  $tmp);             break;         case 3:             $str  =  " 23456789abcdefghjklmnpqrstuvwxyzABCDEFGHIJKLMNPQRSTUVWXYZ ";              $string  = substr (str_shuffle ($STR)  , 0 ,  $num);             break;    }     //fill the background with light color  //the background color is too deep, the verification code will not be clear     imagefilledrectangle ($image  ,  0 , 0 ,  $width  ,  $height  , lightcolor ($image);         4  write character     for on canvas ($i  = 0;  $i < $num;  $i + +)  {  / /Because we set the output 5  characters, so $i is less than $num        //floor is rounding, $width  /   $num   Divide the width of the $num block, * $i is a character to occupy a piece of land, so as not to be piled up in a piece          $x  =  floor ($width  /  $num)  *  $i;         $y  =  mt_rand (10 ,  $height  - 20);         imagechar   ($image  , 5 ,  $x  ,  $y  ,  $string [$i] , deepcolor ($image ));    }        //5  draw interference lines, points      //Interference Line     for ($i  = 0;  $i < $num;  $i + +)  {         imagearc  ($image  , mt_rand (10 ,  $width)  , mt_ Rand (10&NBSP;,&NBSP; $height)  , mt_rand (10 ,  $width)  , mt_rand (10 ,  $height)    mt_rand (0 , 10)  , mt_rand (0 , 270)  , deepcolor ($image));             }    //Interference points      for (  $i  = 0;  $i <50;  $i + +)  {         imagesetpixel ($image  , mt_rand (0 ,  $width)  , mt_rand (0 , $ Height)  , deepcolor ($image));     }    ob_clean ();//Erase Buffer       //6  tells the browser output format: Png    header ("content-type:  Image/png ");        //7  output picture     imagepng ($ Image);        //8  destroy     imagedestroy ($image) ;         return  $string;    //echo  $string;} Set the depth color function lightcolor  ($image)  {    return imagecolorallocate ($ Image , mt_rand (120 , 255)  , mt_rand (120 , 255)  , mt_rand ( 120 , 255)); }function deepcolor  ($image)  {    return  Imagecolorallocate ($image  , mt_rand (0 , 120)  , mt_rand (0 , 120)    mt_rand (0 , 120)); }    ?>

Special Note:

Ob_clean ();//Erase Buffer

This was not added before, and the result tells me "cannot be displayed because of errors", such as:

Fortunately, Baidu found the answer: 50845075. Plus, it's easy to solve the problem, and now the effect is this:

All right.

PHP Implementation Verification Code