Php verification code image generation tutorial _ PHP Tutorial

Php to generate verification code pictures from entry and proficient tutorials. It is quite simple to generate a verification code Image in php, because the graphic gd is provided for us in php. dll library, to enable the gd graphics library, we only need. in ini, it is quite simple to generate a verification code Image in php by taking the php-gd in front of it, because the graphic gd is provided for us in php. dll library, to enable the gd graphics library, we only need. in ini, set php-gd to the previous one.

Method 1

The code is as follows:
$ Authnum = ''; $ Ychar = ", 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); // delimiter function For ($ I = 0; $ I <4; $ I ++ ){ $ Randnum = rand (0, 35 ); $ Authnum. = $ list [$ randnum]; // output as an array

Method 2:

The code is as follows:
Private function createCheckCode () { For (I = 0; I CodeNum; I ++) { Number = rand (0, 2 ); Switch (number) { Case 0: rand_number = rand (48, 57); break; // number Case 1: rand_number = rand (); break; // uppercase letter Case 2: rand_number = rand (97,122); break; // lowercase letter } $ Asc = sprintf ("% c", rand_number ); $ Asc_number = asc_number.asc; } Return asc_number; }

Method 3:

The code is as follows:
Srand (microtime () * 100000); // equivalent to a timer $ String = "abcdefghigklmnopqrstuvwxyz123456789 "; For ($ I = 0; $ I <4; $ I ++) { $ New_number. = $ string [rand (0, strlen ($ string)-1)]; // An array is generated immediately. }

Method 4:

The code is as follows:
For ($ I = 0; $ I <4; $ I ++) { $ Rand. = dechex (rand (); // Convert decimal to hexadecimal }

Code for randomly generating numbers and letters:

The code is as follows:

// 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); // specifies the background color when the palette is used for the first time. $ Te = imagecolorallocate ($ im, 255,255,255 ); Imagestring ($ image, 6, rand (0, 20), rand (0, 2), $ rand, $ te ); Ob_clean (); // The Image "http: // localhost/**. PHP" is displayed on the php webpage because the verification code is generated. Header ("Content-type: image/jpeg"); imagejpeg ($ image ); ?>

Draw the interference line code for the image:

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 colors Imageline ($ im, rand (10, 40), 0, rand (10, 40), 20, $ cg ); }

Draw the interference point code for the image:

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:

The code is as follows:
$ Str = array ('my', 'my', 'login', 'login'); // store the displayed Chinese characters For ($ I = 0; $ I <4; $ I ++) { $ Sss. = $ str [rand ()]; // randomly display Chinese characters } // $ Str = iconv ("gb2312", "UTF-8", $ str); // Chinese character encoding conversion, which does not seem to require me Imagettftext ($ im, 10, 0, rand (5, 60), rand (5, 60), $ te, "simhei. ttf", $ sss );//

Finally, we will share a complete instance.

The code is as follows:

/** * Generate a verification code Image * * @ Param String $ name of the variable in the session of the word verification code */ Function valiCode ($ word = 'randcode '){ Header ("Content-type: image/gif "); $ Border = 0; // whether the border is required; 1: 0: not required $ How = 4; // Number of digits of the verification code $ W = $ how * 15; // image width $ H = 18; // Image height $ Fontsize = 10; // font size $ Alpha = "abcdefghijkmnpqrstuvwxyz"; // verification code content 1: letter $ Number = "23456789"; // verification code content 2: number $ Randcode = ""; // verification code string initialization Srand (double) microtime () * 1000000); // initialize the random number seed $ Im = ImageCreate ($ w, $ h); // Create a verification image /* * Draw the basic framework */ $ Bgcolor = ImageColorAllocate ($ im, 255,255,255); // you can specify the background color. ImageFill ($ im, 0, 0, $ bgcolor); // fill the background color If ($ border) { $ Black = ImageColorAllocate ($ im, 0, 0, 0); // you can specify the border color. ImageRectangle ($ im, 0, 0, $ W-1, $ H-1, $ black); // draw a border } /* * Generate random characters by bit */ For ($ I = 0; $ I <$ how; $ I ++) { $ Alpha_or_number = mt_rand (0, 1); // letters or numbers $ Str = $ alpha_or_number? $ Alpha: $ number; $ Which = mt_rand (0, strlen ($ str)-1); // specify the character $ Code = substr ($ str, $ which, 1); // Obtain the character $ J =! $ I? 4: $ j + 15; // specifies the position of the painted character. $ Color3 = ImageColorAllocate ($ im, mt_rand (0,100), mt_rand (0,100), mt_rand (0,100); // character color ImageChar ($ im, $ fontsize, $ j, 3, $ code, $ color3); // draw characters $ Randcode. = $ code; // add a verification code string to a bit by bit } /* * Remove comments if you need to add interference. * * The following for () loop is the background interference line code. */ /* + ------------------------------- Start of the background interference line ---------------------------------------------- + */ For ($ I = 0; $ I <5; $ I ++) // draws the background interference line { $ Color1 = ImageColorAllocate ($ im, mt_rand (0,255), mt_rand (0,255), mt_rand (0,255); // interference line color ImageArc ($ im, mt_rand (-5, $ w), mt_rand (-5, $ h), mt_rand (20,300), mt_rand (20,200), 55, 44, $ color1); // interference line } /* + ------------------------------- End of the painted background interference line ------------------------------------ + */ /* * Remove comments if you need to add interference. * * The following for () loop is the background interference point code. */ /* + -------------------------------- Start of the painted background interference point ------------------------------------------ + */ For ($ I = 0; $ I <$ how * 40; $ I ++) // draws background interference points { $ Color2 = ImageColorAllocate ($ im, mt_rand (0,255), mt_rand (0,255), mt_rand (0,255); // interference point color ImageSetPixel ($ im, mt_rand (0, $ w), mt_rand (0, $ h), $ color2); // interference point } /* + -------------------------------- The background interference point is painted. ---------------------------------------- + */ // Write the verification code string to the session to check whether the verification code is correct when the logon information is submitted. for example, $ _ POST ['randcode'] = $ _ SESSION ['randcode'] $ _ SESSION [$ word] = $ randcode; /* Drawing ends */ Imagegif ($ im ); ImageDestroy ($ im ); /* Drawing ends */ }

The call method is also very easy to save the img. php file of the above instance, and then on the page to be called
The html page is as follows:

The code is as follows: