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Php verification code generation and usage

Source: Internet
Author: User
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Note: The following code needs to open the gd library of the php tutorial, modify the configuration of the php. in file, and cancel the semicolon before the commented-out line: extension = php_gd2.dll.

$ Width = 165;
$ Height = 120;
$ Image = imagecreatetruecolor ($ width, $ height );
$ Bg_color = imagecolorallocate ($ image, 255,255,255 );
$ Tm = imagecolorallocate ($ image, 255, 0, 0 );
Imagefilledrectangle ($ image, 0, 0, $ width, $ height, $ bg_color );
Imagefill ($ image, 0, 0, $ bg_color );
/*
// $ Text = random_text (5 );
$ Text = "ffff ";
$ Font = 8;
$ Struft = iconv ("gbk", "UTF-8", $ text );
$ X = imagesx ($ image );
$ Y = imagesy ($ image );
$ Fg_color = imagecolorallocate ($ image, 233,14, 91 );
Imagestring ($ image, $ font, $ x, $ y, $ struft, $ fg_color );
$ _ Session ['captcha '] = $ text;
*/
Header ("content-type: image/png ");
Imagepng ($ image );
Imagedestroy ($ image );

Instance 2

Validate. php

The session recognition is used to slightly improve the php Verification Code currently circulating on the network, add the miscellaneous, and display the numbers in random color to control the display of four digits;

<?
Session_start ();
// Generate a verification code Image
Header ("content-type: image/png ");
$ Im = imagecreate (44,18 );
$ Back = imagecolorallocate ($ im, 245,245,245 );
Imagefill ($ im, 0, 0, $ back); // background

Srand (double) microtime () * 1000000 );
// Generate four digits
For ($ I = 0; $ I <4; $ I ++ ){
$ Font = imagecolorallocate ($ im, rand (100,255), rand (0,100), rand (100,255 ));
$ Authnum = rand (1, 9 );
$ Vcodes. = $ authnum;
Imagestring ($ im, 5, 2 + $ I * 10, 1, $ authnum, $ font );
}

For ($ I = 0; $ I <100; $ I ++) // Add interference pixels
{
$ Randcolor = imagecolorallocate ($ im, rand (0,255), rand (0,255), rand (0,255 ));
Imagesetpixel ($ im, rand () % 70, rand () % 30, $ randcolor );
}
Imagepng ($ im );
Imagedestroy ($ im );

$ _ Session ['vcode'] = $ vcodes;
?>

The following describes the complete instance.

<? Php

@ Header ("content-type: text/html; charset = UTF-8 ");

// Open the session

Session_start ();

?>

<Html>

<Head>

<Meta http-equiv = "content-type" content = "text/html; charset = UTF-8"/>

<Title> php verification code example </title>

</Head>

<Body>

Verification Code: <br/>

<Iframe id = "iimg" height = "100" width = 300 src = "img. php" frameborder = "0"> </iframe>

<Br/>

<Input type = button value = "cannot see clearly, change to" onclick = "iimg. location. reload ();">

<Br>

<Form action = "validate. php" method = "post">

Enter the verification code: <input name = "imgid" style = "width: 60">

<Input type = "submit" value = "OK">

</Form>

</Body>

</Html>

Php checks whether the verification code entered by the user is consistent with that generated by the system.

<? Php @ header ("content-type: text/html; charset = UTF-8 ");

// Enable session

Session_start ();

// Obtain the verification code entered by the user and convert it to uppercase.

$ Imgid_req =$ _ request ['imgid'];

$ Imgid_req = strtoupper ($ imgid_req );

// Verify whether the session variable is registered for the string

If (session_is_registered ($ imgid_req )){

Echo "<font color = blue> Verification passed! </Font> ";

} Else {

Echo "<font color = red> verification error! </Font> ";

}

// Close the session to clear all registered Variables

Session_destroy ();

?>

This article is an English version of an article which is originally in the Chinese language on aliyun.com and is provided for information purposes only. This website makes no representation or warranty of any kind, either expressed or implied, as to the accuracy, completeness ownership or reliability of the article or any translations thereof. If you have any concerns or complaints relating to the article, please send an email, providing a detailed description of the concern or complaint, to info-contact@alibabacloud.com. A staff member will contact you within 5 working days. Once verified, infringing content will be removed immediately.

Related Keywords:
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