PHP image verification code production and implementation sharing (full)_PHP tutorial

Just like when I encountered the random function rand() today, I thought about what to do with it. Finally, I remembered the verification code, numeric verification code, letter verification code, and Chinese verification code, but I don’t know how to do it. What should I do? Search the Internet, look at other people's codes, if you don't understand them, watch videos, listen to the teacher's lectures, take notes on the functions you encounter, and the noteworthy points. Usually, you see random verification codes on general web pages that are based on a certain number. Surrounded by a box, it seems to be with the picture as the background. After watching and typing by myself, although I encountered many problems that I didn't know, I believe that as long as I keep my feet on the ground, I will definitely learn it. Now I want to make a summary. My writing may be very messy, but I believe it will be realized one day. 1. Generate random numbers - "Create a picture -" Write the random number into the image - "Add interference values ​​(points, lines) to the image -" Keep it in the session - "Reference it in the form; random Function: rand (int min, int max); it never changes without its origin. I have seen many codes for generating random numbers on the Internet, including random numbers with numbers and letters, Chinese random numbers (arrays), etc.; they are all inseparable from rand. (); The code is as follows (some people copy it online, I hope you don’t take it personally. The first one:

Copy code The code is as follows:

$authnum='';
$ychar="0,1,2,3,4,5,6,7,8,9,A,B,C,D,E,F,G,H ,I,J,K,L,M,N,O,P,Q,R,S,T,U,V,W,X,Y,Z";
$list=explode(",", $ychar);//Split function
for($i=0;$i<4;$i++){
$randnum=rand(0,35);
$authnum.=$list[ $randnum];//Output in the form of array

Second type:

Copy code The code is as follows:

private function createCheckCode()
{
for(i=0;icodeNum;i++)
{
number = rand(0,2);
switch(number)
{
case 0: rand_number = rand(48,57); break;//Number
case 1: rand_number = rand(65,90);break;// Uppercase letters
case 2: rand_number = rand(97,122);break;//lowercase letters
}
$asc = sprintf("%c",rand_number);
$asc_number = asc_number.asc ;
}
return asc_number;
}

Third type:

Copy code The code is as follows :

srand(microtime()*100000);//Equivalent to timer
$string="abcdefghigklmnopqrstuvwxyz123456789";
for($i=0;$i<4; $i++)
{
$new_number.=$string[rand(0,strlen($string)-1)];//Suddenly generate an array
}

Fourth method:

Copy code The code is as follows:

for($i=0;$i<4;$ i++)
{
$rand.=dechex(rand(1,15));//Convert decimal to hexadecimal
}

GD library: ( Provides a series of IPI for image processing functions to generate image processing images)
Enable the GD library in php: In the php.ini configuration file, remove the ";" in ";extension=php_gd2.dll";
Part of the GD Introduction to library functions: 1.imagecreatetruecolor(int x_size,int Y_size) Create a new true color image
2.imagecolorallocate(resource image,int red,int green,int blue) Assign a color to an image, three primary colors
3 .imagestring (resource, font, int x, int y, content, color) drawing function 4. header ("Content-type: image/jpeg") The header of the output function php is an action that defines the header. php5 supports 3 types : 1, Content-type: xxxx/yyyy 2, Location: xxxx:yyyy/zzzz 3, Status: nnn xxxxxx xxxx/yyyy indicates the type of content file such as: image/gif image/jpeg image/png imagejpeg(), imagegif( ),imagepang() 5.iamgeline(resource image,int x1,int y1,int x2,int y2,int color); Line drawing function, (int x,int y) starting coordinates 6.imagesetpixel(resource image,int x,int y,int color) Draw point function 7.imagettftext(resource image,float size,float angle,int x,int y,int color,string fontfile,string text) Write function with font 8.iconv("gb2312 ","utf-8","string"); //First, convert the text into utf-8 format and insert the php verification code into Chinese.

Randomly generate numbers and letters of code:

Copy code The code is as follows:

< ;?php
//che.php
session_start();
for($i=0;$i<4;$i++)
{
$rand.=dechex(rand (1,15));
}
$_SESSION['check_num']=$rand;
$image=imagecreatetruecolor(50,30);
$bg=imagecolorallocate($im,0 ,0,0);//The first time you use the palette, the background color is
$te=imagecolorallocate($im,255,255,255);
imagestring($image,6,rand(0,20) ,rand(0,2),$rand,$te);
ob_clean();//The image "http://localhost/**.php" appears in the PHP web page because it needs to generate a verification code because of its own Error cannot be displayed
header("Content-type:image/jpeg"); imagejpeg($image);
?>

Code to draw interference lines on the picture:

Copy the code The code is as follows:

for($i=0; $i<8;$i++)//Draw multiple lines
{
$cg=imagecolorallocate($im,rand(0,255),rand(0,255),rand(0,255));//Generate random Color
imageline($im,rand(10,40),0,rand(10,40),20,$cg);
}

Draw interference to the picture Point code:

Copy code The code is as follows:

for($i=0;$i<80;$i++ )//Draw multiple points
{
imagesetpixel($im,rand(0,40),rand(0,20),$cg);
}

Write text into the image code:

Copy code The code is as follows:

$str=array('I',' I',' dear',' dear');//Storage the displayed Chinese characters
for($i=0;$i<4;$i++)
{
$sss.=$str[ rand(0,3)];//Randomly display Chinese characters
}

//$str=iconv("gb2312","utf-8",$str); //Chinese character encoding conversion, I don’t seem to need it
imagettftext($im,10,0,rand(5,60),rand(5,60),$te,"simhei.ttf",$sss);//

0: font inclination, "simhei.ttf": font style, usually placed in the root directory;

http://www.bkjia.com/PHPjc/325469.htmlwww.bkjia.comtruehttp: //www.bkjia.com/PHPjc/325469.htmlTechArticle Just as I encountered the random function rand() today; I thought of what to do with it, and finally I remembered I got the verification code, numeric verification code, letter verification code, Chinese verification code, but I don’t know how to do it, so...