A Practical php verification code function

This article mainly introduces the php verification code function in detail, as well as the function for generating image verification codes in PHP for your reference, interested friends can refer to the examples in this article to share with you several php verification code functions, which are very practical. the specific content is as follows:

Code snippet 1:Simple php verification code function

<?php  function code(){  $im = imagecreatetruecolor(100, 40);  $black = imagecolorallocate($im, 0, 0, 0);  $white = imagecolorallocate($im, 255, 255, 255);    imagefill($im,0,0,$white);  $strarr=array_merge(range(0,9),range(a,z),range(A,Z));  shuffle($strarr);  $str=join(array_slice($strarr,0,4));  $mm=rand(0,40);  $aaa=rand(0,0);  $bbb=rand(0,255);  $ccc=rand(0,255);  $color1=imagecolorallocate($im,$aaa,$bbb,$ccc);  imagestring($im,5,$mm,10,$str,$color1);  for($i=0;$i<700;$i++){    $aa=rand(0,255);    $bb=rand(0,255);    $cc=rand(0,255);  $color=imagecolorallocate($im,$aa,$bb,$cc);    $a=rand(0,100);    $b=rand(0,40);    imagesetpixel($im,$a,$b,$color);  }  for($t=0;$t<3;$t++){    $a1=rand(0,255);    $b1=rand(0,255);    $c1=rand(0,255);  $color2=imagecolorallocate($im,$a1,$b1,$c1);    $a2=rand(0,100);    $b2=rand(0,40);    $a3=rand(0,100);    $b3=rand(0,40);    imageline($im,$a2,$b2,$b3,$b3,$color2);  }    header("content-type:image/png");  imagepng($im);  }  code() ; ?>

Code Segment 2:Php verification code function

function _code($_code_length = 4, $_width = 75, $_height = 25){ for($i=0;$i<$_code_length;$i++){  $_nmsg .= dechex(mt_rand(0,15)); } $_SESSION["code"] = $_nmsg; $_img = imagecreatetruecolor($_width, $_height); $_white = imagecolorallocate($_img, 250, 250, 250); imagefill($_img, 0, 0, $_white); $_gray = imagecolorallocate($_img, 196, 196, 196); imagerectangle($_img, 0, 0, $_width-1, $_height-1, $_gray); for ($i=0; $i < 6; $i++) {   $_md_color = imagecolorallocate($_img, mt_rand(200,255), mt_rand(200,255), mt_rand(200,255));  imageline($_img, mt_rand(0,$_width), mt_rand(0, $_height),mt_rand(0,$_width), mt_rand(0, $_height), $_md_color); } for ($i=0; $i < 50; $i++) {   $_md_color = imagecolorallocate($_img, mt_rand(200,255), mt_rand(200,255), mt_rand(200,255));  imagestring($_img, 1, mt_rand(1,$_width-5), mt_rand(1, $_height-5), "*", $_md_color); } for ($i=0; $i < $_code_length ; $i++) {   $_md_color = imagecolorallocate($_img, mt_rand(0,102), mt_rand(0,102), mt_rand(0,102));  imagestring($_img, 5, $i * $_width/$_code_length+ mt_rand(1, 10), mt_rand(1, $_height/2), $_SESSION["code"][$i], $_md_color); } header("Content-Type:image/png"); imagepng($_img); imagedestroy($_img);}

Code snippet 3:Php image verification code function

/* @ Captcha () function: generate a verification code * @ customizable parameter: * @ $ width image width. the default value is 80 * @ $ high, the default value is 25 * @ $ num. the default value is 4 * @ $ line_num. the default value is 10 * @ $ snow_num, default 50 */function captcha ($ width = 80, $ high = 25, $ num = 4, $ line_num = 10, $ snow_num = 50) {header ('content-Type: image/png '); session_start (); // generate random numbers + letters for ($ a = 0; $ a <$ num; $ a ++) {$ code. = dechex (mt_rand (0, 15 )); // dechex-decimal to hexadecimal} // Save the generated verification code in the SESSION Super Global Array $ _ SESSION ['captcha '] = $ code; // Create a canvas $ img = imagecreatetruecolor ($ width, $ high); // fill in the background color in white $ backcolor = imagecolorallocate ($ img, '123456', '123456 ', '000000'); imagefill ($ img, '0', '0', $ backcolor); // add a black border $ bordercolor = imagecolorallocate ($ img, 0, 0, 0); imagerectangle ($ img, 0, 0, $ width-1, $ high-1, $ bordercolor); // randomly draw a line for ($ I = 0; $ I <$ line_num; $ I ++) {imageline ($ img, mt_rand (0, $ width * 0.1), mt_rand (0, $ high ), mt_rand ($ width * 0.9, $ width), mt_rand (0, $ high), imagecolorallocate ($ img, mt_rand (150,255), mt_rand (150,255 ), mt_rand (150,255);} // random snowflake for ($ I = 0; $ I <$ snow_num; $ I ++) {imagechar ($ img, 1, mt_rand (0, $ width), mt_rand (0, $ high), '*', imagecolorallocate ($ img, mt_rand (200,255), mt_rand (200,255 ), mt_rand (200,255);} // draw a verification code for ($ B = 0; $ B <strlen ($ _ SESSION ['captcha ']); $ B ++) {imagechar ($ img, 5, $ B * $ width/$ num + mt_rand (5, 10), mt_rand (2, $ high/2 ), $ _ SESSION ['captcha '] [$ B], imagecolorallocate ($ img, mt_rand (10,150), mt_rand (10,150), mt_rand (0,100);} ob_clean (); // clear the output buffer imagepng ($ img); imagedestroy ($ img );}

The above are three pieces of php verification code functions with high reference, and hope to help you learn php programming.