PHP generate Captcha pictures from the Getting Started and proficient tutorial _php tutorial

In PHP to generate verification code picture is quite simple, because in PHP provides us with the graphics Gd.dll Library, to enable the GD graphics library we just put PHP-GD in front of the php.ini;

Method One

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$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 as an array

Method Two:

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Private Function Createcheckcode () { For (i=0;i codenum;i++) { Number = rand (0,2); Switch (number) { Case 0:rand_number = rand (48,57); break;//Digital Case 1:rand_number = rand (65,90); break;//Capital 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 Three:

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Srand (Microtime () *100000);//equivalent to a timer $string = "abcdefghigklmnopqrstuvwxyz123456789"; for ($i =0; $i <4; $i + +) { $new _number.= $string [Rand (0,strlen ($string)-1)];//immediately produces an array }

Method Four:

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

Randomly generated numbers, letters of code:

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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);//When using the palette for the first time, the background color $te =imagecolorallocate ($im, 255,255,255); Imagestring ($image, 6,rand (0,20), Rand (0,2), $rand, $te); Ob_clean (); the image "Http://localhost/**.php" appears in the//php Web page because it has to generate a verification code and cannot be displayed because of its own error Header ("Content-type:image/jpeg"); Imagejpeg ($image); ?>

To draw an interference line code for a picture:

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for ($i =0; $i <8; $i + +)//Draw more than one line { $CG =imagecolorallocate ($im, Rand (0,255), Rand (0,255), Rand (0,255));//produce random colors Imageline ($im, Rand (10,40), 0,rand (10,40), $CG); }

To draw a code for the image to the point of interference:

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for ($i =0; $i <80; $i + +)//Draw multiple points { Imagesetpixel ($im, Rand (0,40), Rand (0,20), $CG); }

Write the text to the image code:

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$str =array (' i ', ' I ', ' pro ', ' Pro ');//store displayed Kanji for ($i =0; $i <4; $i + +) { $sss. = $str [Rand (0,3)];//random display of Chinese characters } $str =iconv ("gb2312", "Utf-8", $str); Chinese character coding transformation, I don't seem to need Imagettftext ($im, 10,0,rand (5,60), Rand (5,60), $te, "Simhei.ttf", $sss);//

Finally, we share a complete example with the actual

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/** * Generate Verification Code picture * * @param String $word The variable name of the CAPTCHA in session */ function Valicode ($word = ' Randcode ') { Header ("Content-type:image/gif"); $border = 0; Whether to border 1 to: 0 do not $how = 4; Verify number of code bits $w = $how *15; Picture width $h = 18; Picture height $fontsize = 10; Font size $alpha = "ABCDEFGHIJKMNPQRSTUVWXYZ"; Verification Code Content 1: Letters $number = "23456789"; Verification Code Content 2: Digital $randcode = ""; Validation code string initialization Srand (Double) microtime () *1000000); Initialize random number Seed $im = Imagecreate ($w, $h); Create a validation picture /* * Draw the basic frame */ $bgcolor = Imagecolorallocate ($im, 255, 255, 255); Set Background color Imagefill ($im, 0, 0, $bgcolor); Fill background color if ($border) { $black = imagecolorallocate ($im, 0, 0, 0); Set Border color Imagerectangle ($im, 0, 0, $w-1, $h-1, $black);//Draw Border } /* * Random character generation by bit */ for ($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); which character to take $code = substr ($str, $which, 1); Take character $j =! $i? 4: $j +15; Draw character position $color 3 = imagecolorallocate ($im, Mt_rand (0,100), Mt_rand (0,100), Mt_rand (0,100)); Character Color Imagechar ($im, $fontsize, $j, 3, $code, $color 3); Paint characters $randcode. = $code; Add a CAPTCHA string to a bit } /* * Remove Comments If you need to add interference * * the following for () loop draws the background noise line code */ /* +-------------------------------Draw background noise line start--------------------------------------------+ */ for ($i =0; $i <5; $i + +)//Draw background interference line { $color 1 = imagecolorallocate ($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), $color 1); Interference Line } /* +-------------------------------Draw background interference line end--------------------------------------+ */ /* * Remove Comments If you need to add interference * * the following for () loop draws the background noise point code */ /* +--------------------------------Draw background noise point start------------------------------------------+ */ for ($i =0; $i < $how *40; $i + +)//plot background interference points { $color 2 = imagecolorallocate ($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), $color 2); Interference Point } /* +--------------------------------Draw background noise point end------------------------------------------+ */ Write the captcha string to the SESSION to verify that the verification code is correct when you submit the login information for example: $_post[' randcode '] = $_session[' Randcode ') $_session[$word] = $randcode; /* End of drawing */ Imagegif ($im); Imagedestroy ($im); /* End of drawing */ }

The calling method is also very simple to save the above instance to the img.php file, and then on the page to invoke
The HTML page is as follows

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This will enable the verification code to be called.

Add a commit verification verification code is correct

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Session_Start (); if ((Strtoupper ($_post["code")) = = Strtoupper (($_session["Verifycode"])) { Print ("Verification code is correct,"); }else{ Print ("Captcha error,"); } ?>

This is what we have done from the generation of CAPTCHA images and use of the entire process, but also from the beginning of PHP to proficient verification code is all said.

http://www.bkjia.com/PHPjc/631625.html www.bkjia.com true http://www.bkjia.com/PHPjc/631625.html techarticle in PHP to generate verification code picture is quite simple, because in PHP provides us with the graphics Gd.dll Library, to enable the GD graphics library we just put PHP-GD in front of the php.ini;

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