PHP generates an example of an image verification code, _php tutorial

PHP generates an example of a picture verification code to explain,

In this paper, we demonstrate 5 kinds of verification codes, and describe the function of generating verification code. PHP generated Verification code principle: Through the GD library, generate a picture with a verification code, and save the Verification code in the session.

1. HTML
5 The code is as follows:

1. Digital Verification Code
Verification Code:
   
2, Digital + Letter verification Code
Verification Code:
   
3. Chinese Verification Code
Verification Code:
   
4, imitation Google verification code
Verification Code:
   
5. Arithmetic Verification Code
Verification Code:

2. JS Verification

$ (function () {$ ("#getcode_num"). Click (function () {//Digital authentication $ (this). attr ("src", ' code_num.php ' + math.random ());}); $ ("  #chk_num "). Click (function () {var code_num = $ (" #code_num "). Val (); $.post ("Chk_code.php?act=num", {code:code_num}, function (msg) {if (msg = = 1) {alert ("The CAPTCHA is correct!")   "); } else {alert ("CAPTCHA Error!   "); }  }); }); Number + Letter Verification $ ("#getcode_char"). Click (function () {$ (this). attr ("src", ' code_char.php ' + math.random ());});  $ ("#chk_char"). Click (function () {var Code_char = $ ("#code_char"). Val (); $.post ("Chk_code.php?act=char", {Code:code_char}, function (msg) {if (msg = = 1) {alert ("The CAPTCHA is correct!")   "); } else {alert ("CAPTCHA Error!   "); }  }); }); Chinese captcha $ ("#getcode_zh"). Click (function () {$ (this). attr ("src", ' code_zh.php ' + math.random ());});  $ ("#chk_zh"). Click (function () {var Code_zh = Escape ($ ("#code_zh"). Val ()); $.post ("Chk_code.php?act=zh", {Code:code_zh}, function (msg) {if (msg = = 1) {alert ("The CAPTCHA is correct!")   "); } else {alert ("CAPTCHA Error!   ");}  }); }); Google verified $ ("#getcode_gg"). Click (function () {$ (this). attr ("src", ' code_gg.php ' + math.random ());});  $ ("#chk_gg"). Click (function () {var code_gg = $ ("#code_gg"). Val (); $.post ("Chk_code.php?act=gg", {Code:code_gg}, function (msg) {if (msg = = 1) {alert ("The CAPTCHA is correct!")   "); } else {alert ("CAPTCHA Error!   "); }  }); }); Arithmetic validation $ ("#getcode_math"). Click (function () {$ (this). attr ("src", ' code_math.php ' + math.random ());});  $ ("#chk_math"). Click (function () {var Code_math = $ ("#code_math"). Val (); $.post ("Chk_code.php?act=math", {Code:code_math}, function (msg) {if (msg = = 1) {alert ("The CAPTCHA is correct!")   "); } else {alert ("CAPTCHA Error!   "); }  }); });});

3, PHP generated verification code

Session_Start (); GetCode (4,60,20); function GetCode ($num, $w, $h) {$code = ""; for ($i = 0; $i < $num; $i + +) {$code. = rand (0, 9);}//4-bit verification code can also be generated directly with Rand (1000,9999)//To write the generated verification code to the session, for verification with $_sessi on["Helloweba_num"] = $code; Create a picture, define the color value header ("Content-type:image/png"); $im = Imagecreate ($w, $h); $black = imagecolorallocate ($im, 0, 0, 0); $gray = Imagecolorallocate ($im, 200, 200, 200); $bgcolor = Imagecolorallocate ($im, 255, 255, 255); Fill Background imagefill ($im, 0, 0, $gray); Draw Border Imagerectangle ($im, 0, 0, $w-1, $h-1, $black); Randomly draws two dashed lines, acts as a disturbance $style = Array ($black, $black, $black, $black, $black, $gray, $gray, $gray, $gray, $gray); Imagesetstyle ($im, $style); $y 1 = rand (0, $h); $y 2 = rand (0, $h); $y 3 = rand (0, $h); $y 4 = rand (0, $h); Imageline ($im, 0, $y 1, $w, $y 3, img_color_styled); Imageline ($im, 0, $y 2, $w, $y 4, img_color_styled); A large number of black dots are randomly generated on the canvas, which acts as interference; for ($i = 0; $i <, $i + +) {Imagesetpixel ($im, rand (0, $w), rand (0, $h), $black);}//random display of numbers on the canvas, the horizontal spacing and position of the characters according to a certain fluctuation range Randomly generated $strx = Rand (3, 8);  for ($i = 0; $i < $num; $i + +) {$strpos = rand (1, 6);  Imagestring ($im, 5, $strx, $strpos, substr ($code, $i, 1), $black); $strx + = rand (8, 12); } imagepng ($im);//Output Picture Imagedestroy ($im);//release Image Memory}

The above is the whole content of this article, I hope that everyone's study has helped.

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