PHP generated picture verification code-with five kinds of verification code _php instance

Before the output verification code used a method, in the foreground with JS to generate a code string, and then passed to the background with PHP output CAPTCHA code image. This does not require the use of $_session to pass the verification code value, directly using JS to compare the generated string and the input string is equal.

This article demonstrates 5 kinds of authentication codes with an example, and introduces the function of generating the verification code. PHP generated Verification code principle: Through the GD library, generate a picture with the verification code, and the verification code stored in the session.

1, HTML

The verification code in 5 has the following HTML code:

<div class= "Demo" >


  
 

 <H3>2, Digital + letter verification Code  
  
 
 

 <H3>3, Chinese authentication 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 ("Verify code is correct!) ");
  } else {
  alert ("Authentication code Error!) ");
  }
 });
 });

Digital + 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 (" Verify the code is correct! ");
  } else {
  alert ("Authentication code Error!) ");
  }
 });
 });

Chinese Verification Code

 $ ("#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 ("Verify code is correct!) ");
  } else {
  alert ("Authentication code Error!) ");
  }
 });
 });

Google Verification

 $ ("#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 (" Verify the code is correct! ");
  } else {
  alert ("Authentication code Error!) ");
  }
 });
 });

//Arithmetic verification

 $ ("#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 (" Verify the code is correct! ");
  } else {
  alert ("Authentication code 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);
 The///4-bit captcha can also be generated directly by rand (1000,9999)//To write the generated validation code into session, with $_session["helloweba_num" = $code;
 Create a picture that defines 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, $gray);
 Draw a border Imagerectangle ($im, 0, 0, $w-1, $h-1, $black);
 Randomly draw two dotted lines, interfering $style = Array ($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, $y 4, img_color_styled);
 A large number of black spots are randomly generated on the canvas, which plays a disturbing role.
 for ($i = 0; $i < $i + +) {Imagesetpixel ($im, rand (0, $w), rand (0, $h), $black); ///Display the numbers randomly on the canvas, the horizontal spacing and position of the characters are randomly generated according to certain fluctuation range $strx = rand (3, 8);
 for ($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);//Free up memory for pictures}

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